{"id":12342,"date":"2026-03-02T06:13:26","date_gmt":"2026-03-02T06:13:26","guid":{"rendered":"https:\/\/hlh-js.com\/?p=12342"},"modified":"2026-03-02T07:21:29","modified_gmt":"2026-03-02T07:21:29","slug":"what-pressure-should-you-use-for-plastic-media-blasting","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/es\/resource\/blog\/what-pressure-should-you-use-for-plastic-media-blasting\/","title":{"rendered":"What Pressure Should You Use for Plastic Media Blasting?"},"content":{"rendered":"<!-- ============================================================\n     CLUSTER ARTICLE #13 \u2014 WordPress Post Content\n     Title: What Pressure Should You Use for Plastic Media Blasting?\n     \u7c98\u8d34\u65b9\u5f0f\uff1aGutenberg\u300c\u81ea\u5b9a\u4e49 HTML\u300d\u5757 \u6216 \u7ecf\u5178\u7f16\u8f91\u5668\u300c\u6587\u672c\u300d\u6a21\u5f0f\n     ============================================================ -->\n\n<style>\n\/* \u2500\u2500 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li a{display:flex;align-items:center;gap:8px;color:#1d4ed8;text-decoration:none;font-size:14.5px;padding:8px 12px;border:1px solid #e2e8f0;border-radius:4px;background:#fafafa}\n.pm-cluster-group ul li a:hover{background:#eff6ff;border-color:#bfdbfe}\n.pm-cluster-group ul li a::before{content:\"\u2192\";font-weight:700;flex-shrink:0}\n\n.pm-section-divider{border:none;border-top:1px solid #f1f5f9;margin:48px 0}\n\n@media(max-width:680px){\n  .pm-var-grid{grid-template-columns:1fr 1fr}\n  .pm-substrate-grid{grid-template-columns:1fr}\n  .pm-measure-flow{flex-wrap:wrap;gap:8px}\n  .pm-mf-arrow{display:none}\n  .pm-mf-block{border-radius:6px!important;flex:0 0 calc(50% - 4px)}\n}\n@media(max-width:440px){\n  .pm-gauge-grid{grid-template-columns:1fr 1fr}\n  .pm-var-grid{grid-template-columns:1fr}\n}\n<\/style>\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     INTRO\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h1>What Pressure Should You Use for Plastic Media Blasting?<\/h1>\n<p>Blast pressure is the single most consequential parameter in plastic media blasting \u2014 the variable that most directly controls whether you remove the coating and protect the substrate, or remove the coating and damage the substrate, or fail to remove the coating at all. Every other process variable \u2014 standoff distance, nozzle angle, media mesh size, media type \u2014 operates within the constraints that pressure sets. Get the pressure right and the rest of the process has margin for normal variation. Get it wrong and no amount of technique compensates.<\/p>\n\n<p>Yet pressure is also the parameter most commonly set by guesswork. Operators arriving at a new blast operation frequently ask a colleague what pressure they run, dial in that number without understanding why, and proceed. When results are inconsistent \u2014 too slow, leaving coating, or producing substrate damage \u2014 pressure adjustment is often the first thing tried, again by trial and error, rather than by the systematic logic that connects substrate type, media specification, coating hardness, and the physical mechanism of selective coating removal.<\/p>\n\n<p>This guide eliminates the guesswork. It covers the physics that connect pressure to blast performance, the correct pressure ranges for every major application and substrate type, the variables that interact with pressure and must be considered together, how to measure pressure correctly (not all measurement points give the same number), how to qualify a new pressure setting properly, and what the specific symptoms of under-pressure and over-pressure look like so you can diagnose them before they become quality problems. For the broader setup context, see: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/plastic-media-blasting-step-by-step-setup-guide\/\">Plastic Media Blasting: Step-by-Step Setup Guide<\/a>.For a broader overview of the full plastic media category, see: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/what-is-plastic-media-the-complete-guide-to-types-uses-applications\/\">What Is Plastic Media? The Complete Guide<\/a>.<\/p>\n\n\n<!-- TOC -->\n<nav class=\"pm-toc\" aria-label=\"Table of Contents\">\n  <p class=\"pm-toc-title\">\ud83d\udccb Table of Contents<\/p>\n  <ol>\n    <li><a href=\"#pr-physics\">Why Pressure Matters: The Physics of Blast Impact<\/a><\/li>\n    <li><a href=\"#pr-where\">Where to Measure Pressure (and Where Not To)<\/a><\/li>\n    <li><a href=\"#pr-zones\">The Three Pressure Zones<\/a><\/li>\n    <li><a href=\"#pr-reference\">Master Pressure Reference: All Applications<\/a><\/li>\n    <li><a href=\"#pr-substrate\">Substrate-by-Substrate Pressure Guide<\/a><\/li>\n    <li><a href=\"#pr-variables\">Variables That Interact With Pressure<\/a><\/li>\n    <li><a href=\"#pr-mesh\">How Mesh Size Changes Your Effective Pressure<\/a><\/li>\n    <li><a href=\"#pr-standoff\">Standoff Distance and Angle as Pressure Modifiers<\/a><\/li>\n    <li><a href=\"#pr-too-low\">Signs You Are Running Too Low<\/a><\/li>\n    <li><a href=\"#pr-too-high\">Signs You Are Running Too High<\/a><\/li>\n    <li><a href=\"#pr-qualify\">How to Qualify a New Pressure Setting<\/a><\/li>\n    <li><a href=\"#pr-drift\">Pressure Drift: Why Your Setting Changes Without Touching the Dial<\/a><\/li>\n    <li><a href=\"#pr-troubleshoot\">Pressure Troubleshooting Guide<\/a><\/li>\n    <li><a href=\"#pr-faq\">Preguntas frecuentes<\/a><\/li>\n    <li><a href=\"#pr-related\">Related Guides<\/a><\/li>\n  <\/ol>\n<\/nav>\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 1 \u2014 PHYSICS\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-physics\">Why Pressure Matters: The Physics of Blast Impact<\/h2>\n\n<p>Blast pressure determines the velocity at which media particles leave the nozzle and strike the substrate surface. Velocity is the input; kinetic energy is what matters for coating removal. The kinetic energy of each particle impact scales with the square of velocity \u2014 doubling the blast velocity quadruples the impact energy per particle, not merely doubles it. This nonlinear relationship is why pressure changes have outsized effects on blast aggressiveness: a 20% increase in pressure can increase impact energy by 40\u201350%, pushing a safe process into over-blast territory without any obvious visible indication at the control point.<\/p>\n\n<p>The mechanism of selective coating removal by plastic media \u2014 what makes it possible to remove paint from aluminum without damaging the aluminum underneath \u2014 depends on maintaining impact energy within a window bounded by two physical thresholds. The lower bound is the adhesion strength of the coating to the substrate: impact energy must exceed the coating&#8217;s bond strength to fracture and remove it. The upper bound is the yield strength (or fatigue limit, for repeated impacts) of the substrate material: impact energy must stay below the level that causes plastic deformation, micro-cracking, or surface erosion of the substrate itself.<\/p>\n\n<p>Plastic media&#8217;s fundamental advantage over mineral abrasives is that this window is wider. Mineral abrasives (silica sand, aluminum oxide) have Mohs hardness 6\u20139 \u2014 harder than most substrate materials, which means the lower threshold for substrate damage is near the lower threshold for coating removal. The working window is narrow, and process control is difficult. Plastic media at Mohs 2.5\u20134.0 is harder than most organic coatings but softer than most metallic substrates \u2014 the coating removal threshold and the substrate damage threshold are far apart, creating a wide working window where pressure can vary considerably without catastrophic results in either direction.<\/p>\n\n<div class=\"pm-callout\">\n  <strong>The nonlinear pressure-energy relationship in practice:<\/strong> This is why &#8220;start low and go up in small increments&#8221; is not just caution \u2014 it is physics. Moving from 25 PSI to 35 PSI (a 40% pressure increase) increases particle velocity approximately 17% but increases impact energy approximately 37%. Moving from 35 PSI to 50 PSI (a 43% pressure increase) roughly doubles the impact energy. Each pressure increment above the minimum effective level represents a disproportionate increase in substrate damage risk.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 2 \u2014 WHERE TO MEASURE\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-where\">Where to Measure Pressure (and Where Not To)<\/h2>\n\n<p>One of the most consistently underestimated sources of process error in blast operations is measuring pressure at the wrong point in the system and assuming that number reflects what is actually happening at the substrate. There are three common measurement points in a blast system, and they give three different readings \u2014 only one of which is the operationally correct value.<\/p>\n\n<div class=\"pm-measure-flow\">\n  <div class=\"pm-mf-block\">\n    <span class=\"pm-mf-icon\">\ud83c\udfed<\/span>\n    <div class=\"pm-mf-name\">Compressor Outlet<\/div>\n    <div class=\"pm-mf-psi\">90\u2013120 PSI<\/div>\n    <div class=\"pm-mf-note\">Tank \/ line pressure. Not the operating pressure. Never use this as your process reference.<\/div>\n  <\/div>\n  <div class=\"pm-mf-arrow\">\u2192<\/div>\n  <div class=\"pm-mf-block\">\n    <span class=\"pm-mf-icon\">\u2699\ufe0f<\/span>\n    <div class=\"pm-mf-name\">Blast Pot Regulator<\/div>\n    <div class=\"pm-mf-psi\">Set point PSI<\/div>\n    <div class=\"pm-mf-note\">Regulated inlet to pot. 10\u201320 PSI higher than nozzle pressure at full blast flow. Common but incorrect reference point.<\/div>\n  <\/div>\n  <div class=\"pm-mf-arrow\">\u2192<\/div>\n  <div class=\"pm-mf-block\">\n    <span class=\"pm-mf-icon\">\ud83d\udccf<\/span>\n    <div class=\"pm-mf-name\">Nozzle Inlet Gauge<\/div>\n    <div class=\"pm-mf-psi\">True operating PSI<\/div>\n    <div class=\"pm-mf-note\">\u2705 The correct measurement point. What the particle actually experiences. All pressure specifications in this guide reference this point.<\/div>\n  <\/div>\n  <div class=\"pm-mf-arrow\">\u2192<\/div>\n  <div class=\"pm-mf-block\">\n    <span class=\"pm-mf-icon\">\ud83d\udca8<\/span>\n    <div class=\"pm-mf-name\">Nozzle Exit \/ Substrate<\/div>\n    <div class=\"pm-mf-psi\">~0 PSI gauge<\/div>\n    <div class=\"pm-mf-note\">Atmospheric pressure at exit. Particle velocity is determined by the pressure drop across the nozzle, which is governed by nozzle inlet pressure.<\/div>\n  <\/div>\n<\/div>\n\n<h3>The Hose Drop Problem<\/h3>\n<p>Pressure drop across a blast hose at high blast flow rates is typically 5\u201315 PSI depending on hose length, inside diameter, and flow velocity. A 50-foot hose at 3\/8-inch nozzle flow rates loses approximately 8\u201312 PSI between the pot regulator and the nozzle inlet. If you set the pot regulator to 40 PSI, the nozzle may be receiving only 28\u201332 PSI \u2014 20\u201330% below the intended operating pressure. This is not an edge case; it is the normal operating condition of most blast setups that do not have a nozzle inlet gauge installed.<\/p>\n\n<p>The fix is simple and inexpensive: install a tee fitting and low-range pressure gauge (0\u201360 PSI range, not the standard 0\u2013200 PSI gauge, which reads poorly at the low end of plastic media operating pressures) at the nozzle inlet, 6\u201312 inches upstream of the nozzle entry. All pressure specifications in this guide are referenced to this measurement point. When qualifying a new process or verifying an established one, always confirm pressure at the nozzle inlet gauge under active blast conditions \u2014 not at the pot regulator and not with the blast trigger released.<\/p>\n\n<div class=\"pm-callout pm-callout-warn\">\n  <strong>Use a low-range gauge at the nozzle:<\/strong> Standard blast equipment gauges (0\u2013200 PSI) have very low resolution at the 15\u201350 PSI range where plastic media blasting operates \u2014 each graduation may represent 5 PSI or more, making it impossible to set or confirm pressure to the \u00b12 PSI precision that sensitive applications require. Install a dedicated 0\u201360 PSI gauge at the nozzle inlet for any application involving aluminum, composites, or other damage-sensitive substrates.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 3 \u2014 THREE ZONES\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-zones\">The Three Pressure Zones<\/h2>\n\n<p>Across all plastic media applications, nozzle inlet pressure operates in one of three functional zones. Understanding which zone each application falls into provides an immediate framework for setting starting parameters before qualification:<\/p>\n\n<div class=\"pm-gauge-grid\">\n  <div class=\"pm-gauge-card zone-low\">\n    <div class=\"pm-gauge-header\">\ud83d\udfe2 Precision Zone<\/div>\n    <div class=\"pm-gauge-body\">\n      <div class=\"pm-gauge-psi\">8\u201325<\/div>\n      <div class=\"pm-gauge-unit\">PSI<\/div>\n      <div class=\"pm-gauge-app\">CFRP composites \u00b7 Polished mold cavities \u00b7 Electronics deflashing \u00b7 Beryllium copper \u00b7 Optical surfaces \u00b7 Aluminum aircraft skin (thin gauge)<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-gauge-card zone-low\">\n    <div class=\"pm-gauge-header\">\ud83d\udfe2 Standard Zone<\/div>\n    <div class=\"pm-gauge-body\">\n      <div class=\"pm-gauge-psi\">25\u201345<\/div>\n      <div class=\"pm-gauge-unit\">PSI<\/div>\n      <div class=\"pm-gauge-app\">Aluminum structure (6061, 7075) \u00b7 Automotive body panels (steel) \u00b7 Standard injection mold cleaning \u00b7 Pre-anodize finishing \u00b7 General aerospace depainting<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-gauge-card zone-mid\">\n    <div class=\"pm-gauge-header\">\ud83d\udfe1 Aggressive Zone<\/div>\n    <div class=\"pm-gauge-body\">\n      <div class=\"pm-gauge-psi\">45\u201365<\/div>\n      <div class=\"pm-gauge-unit\">PSI<\/div>\n      <div class=\"pm-gauge-app\">Heavy steel structure \u00b7 Chassis \/ frame work \u00b7 Thick industrial coatings on steel \u00b7 Die casting dies (H13, properly cooled) \u00b7 Rubberized underseal removal<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-gauge-card zone-high\">\n    <div class=\"pm-gauge-header\">\ud83d\udd34 Maximum Zone<\/div>\n    <div class=\"pm-gauge-body\">\n      <div class=\"pm-gauge-psi\">65\u201380<\/div>\n      <div class=\"pm-gauge-unit\">PSI<\/div>\n      <div class=\"pm-gauge-app\">Very limited use cases only. Heavy epoxy or polyurethane coatings on thick steel where dimensional tolerance is not a concern. Rarely justified for plastic media \u2014 mineral abrasive is usually more appropriate above 65 PSI.<\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<div class=\"pm-callout pm-callout-orange\">\n  <strong>The starting rule:<\/strong> For any new application, start at the lowest pressure in the applicable zone and work upward. The lowest pressure that achieves complete coating removal in an acceptable cycle time is the correct operating pressure \u2014 not the highest pressure that does not produce visible substrate damage. The difference between &#8220;minimum effective&#8221; and &#8220;maximum safe&#8221; represents your process margin; operating at the minimum preserves that entire margin as a buffer against process variation.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 4 \u2014 MASTER REFERENCE TABLE\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-reference\">Master Pressure Reference: All Applications<\/h2>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Aplicaci\u00f3n<\/th>\n        <th>Tipo de medio<\/th>\n        <th>Mesh Size<\/th>\n        <th>Pressure Range (Nozzle Inlet)<\/th>\n        <th>Starting Point<\/th>\n        <th>Notes<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>CFRP \/ composite structure (aerospace)<\/td>\n        <td>Type V Acrylic<\/td>\n        <td>Mesh 30\u201340<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">20\u201335 PSI<\/span><\/td>\n        <td>20 PSI<\/td>\n        <td>Never exceed 40 PSI on CFRP. Fiber damage is irreversible and may not be visible \u2014 requires NDI verification at qualification.<\/td>\n      <\/tr>\n      <tr>\n        <td>Aluminum aircraft skin (0.020\u20130.063\u2033 thick)<\/td>\n        <td>Urea de tipo II<\/td>\n        <td>Mesh 30\u201340<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">20\u201335 PSI<\/span><\/td>\n        <td>20 PSI<\/td>\n        <td>Almen strip testing required at qualification per most aerospace process specs. Document Almen intensity vs. pressure curve.<\/td>\n      <\/tr>\n      <tr>\n        <td>Aluminum aircraft structure (thicker, >0.063\u2033)<\/td>\n        <td>Urea de tipo II<\/td>\n        <td>Mesh 20\u201330<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">25\u201340 PSI<\/span><\/td>\n        <td>25 PSI<\/td>\n        <td>More latitude than thin skin; still requires Almen testing for fatigue-sensitive structures.<\/td>\n      <\/tr>\n      <tr>\n        <td>Automotive body panel (20\u201324 gauge steel)<\/td>\n        <td>Urea de tipo II<\/td>\n        <td>Mesh 20\u201330<\/td>\n        <td><span class=\"pm-badge pm-badge-green\">25\u201340 PSI<\/span><\/td>\n        <td>28 PSI<\/td>\n        <td>Panel distortion (oil-canning) risk above 40 PSI on 22\u201324 gauge. Run palm check after each panel at a new pressure.<\/td>\n      <\/tr>\n      <tr>\n        <td>Automotive body panel (16\u201318 gauge steel)<\/td>\n        <td>Urea de tipo II<\/td>\n        <td>Mesh 20\u201330<\/td>\n        <td><span class=\"pm-badge pm-badge-green\">30\u201350 PSI<\/span><\/td>\n        <td>30 PSI<\/td>\n        <td>Heavier gauge allows higher pressure. Rocker panels and structural sections: treat as chassis (see below).<\/td>\n      <\/tr>\n      <tr>\n        <td>Automotive chassis \/ frame (heavy steel)<\/td>\n        <td>Type II or III<\/td>\n        <td>Mesh 16\u201320<\/td>\n        <td><span class=\"pm-badge pm-badge-yellow\">45\u201365 PSI<\/span><\/td>\n        <td>45 PSI<\/td>\n        <td>Structural steel tolerates aggressive parameters. Check for pre-existing cracks before blasting \u2014 blasting can open hairline cracks.<\/td>\n      <\/tr>\n      <tr>\n        <td>Aerospace engine nacelle \/ cowl (composite)<\/td>\n        <td>Type V Acrylic<\/td>\n        <td>Mesh 30\u201350<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">15\u201330 PSI<\/span><\/td>\n        <td>15 PSI<\/td>\n        <td>Complex geometry \u2014 adjust standoff to 10\u201314 inches for curved surfaces. Type V mandatory; Type II too aggressive for thin composite skins.<\/td>\n      <\/tr>\n      <tr>\n        <td>Injection mold cleaning (P20 \/ H13 tool steel)<\/td>\n        <td>Type V Acrylic<\/td>\n        <td>Mesh 50\u201380<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">12\u201325 PSI<\/span><\/td>\n        <td>12 PSI<\/td>\n        <td>Measure Ra before first blast and monitor every 5 cycles. If Ra creeps upward, reduce pressure immediately. See mold cleaning guide.<\/td>\n      <\/tr>\n      <tr>\n        <td>Die casting die cleaning (H13, cooled to &lt;150\u00b0F)<\/td>\n        <td>Type V Acrylic<\/td>\n        <td>Mesh 40\u201360<\/td>\n        <td><span class=\"pm-badge pm-badge-green\">20\u201330 PSI<\/span><\/td>\n        <td>20 PSI<\/td>\n        <td>Verify die temperature with IR thermometer before blasting. Above 150\u00b0F surface temp: media softens, embeds, contaminates die surface.<\/td>\n      <\/tr>\n      <tr>\n        <td>Electronics deflashing (IC packages, connectors)<\/td>\n        <td>Type V Acrylic<\/td>\n        <td>Mesh 60\u201380<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">8\u201320 PSI<\/span><\/td>\n        <td>8 PSI<\/td>\n        <td>Fine-pitch IC packages (QFP, LQFP): do not exceed 15 PSI. Lead deformation is permanent. Automated fixturing required above 1,000 pcs\/day.<\/td>\n      <\/tr>\n      <tr>\n        <td>Pre-anodize aluminum finishing<\/td>\n        <td>Type V Acrylic<\/td>\n        <td>Mesh 50\u201380<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">12\u201320 PSI<\/span><\/td>\n        <td>12 PSI<\/td>\n        <td>This is tumbling media territory (vibratory) for most pre-anodize work; blast prep used for complex geometry or large parts. Keep iron contamination to zero.<\/td>\n      <\/tr>\n      <tr>\n        <td>Marine \/ industrial thick coating removal (steel)<\/td>\n        <td>Type II or III<\/td>\n        <td>Mesh 12\u201320<\/td>\n        <td><span class=\"pm-badge pm-badge-yellow\">45\u201365 PSI<\/span><\/td>\n        <td>45 PSI<\/td>\n        <td>Thick coatings may require multiple passes even at maximum pressure. Consider Type III melamine for rubberized coatings that resist Type II.<\/td>\n      <\/tr>\n      <tr>\n        <td>Beryllium copper (mold inserts, connectors)<\/td>\n        <td>Type V Acrylic<\/td>\n        <td>Mesh 60\u201380<\/td>\n        <td><span class=\"pm-badge pm-badge-blue\">10\u201318 PSI<\/span><\/td>\n        <td>10 PSI<\/td>\n        <td>\u26a0\ufe0f Full beryllium PPE protocol required. BeCu softer than steel (RB 96\u2013100). Establish Ra baseline before first blast. Review with safety officer.<\/td>\n      <\/tr>\n      <tr>\n        <td>Titanium aerospace structure<\/td>\n        <td>Type II or III<\/td>\n        <td>Mesh 20\u201330<\/td>\n        <td><span class=\"pm-badge pm-badge-green\">30\u201350 PSI<\/span><\/td>\n        <td>30 PSI<\/td>\n        <td>Titanium is hard (HRC 30\u201336) but fatigue-sensitive. Almen strip testing required at qualification. Do not use parameters derived from steel work without separate testing.<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 5 \u2014 SUBSTRATE BY SUBSTRATE\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-substrate\">Substrate-by-Substrate Pressure Guide<\/h2>\n\n<div class=\"pm-substrate-grid\">\n  <div class=\"pm-substrate-card\">\n    <div class=\"pm-substrate-head steel\">\ud83d\udd29 Mild \/ Low-Carbon Steel<\/div>\n    <div class=\"pm-substrate-body\">\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Standard range<\/span><span class=\"pm-substrate-val\">25\u201350 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Thin gauge (&lt;18 ga)<\/span><span class=\"pm-substrate-val\">25\u201340 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Heavy structural<\/span><span class=\"pm-substrate-val\">45\u201365 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Damage risk at<\/span><span class=\"pm-substrate-val\">&gt;50 PSI (thin) \u2014 warping<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Recommended media<\/span><span class=\"pm-substrate-val\">Type II, Mesh 20\u201330<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-substrate-card\">\n    <div class=\"pm-substrate-head aluminum\">\u2708\ufe0f Aluminum (All Alloys)<\/div>\n    <div class=\"pm-substrate-body\">\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Aircraft skin (thin)<\/span><span class=\"pm-substrate-val\">20\u201335 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Structural \/ machined<\/span><span class=\"pm-substrate-val\">25\u201340 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Die cast (A380\/A356)<\/span><span class=\"pm-substrate-val\">25\u201335 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Damage risk at<\/span><span class=\"pm-substrate-val\">&gt;40 PSI \u2014 surface erosion<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Recommended media<\/span><span class=\"pm-substrate-val\">Type II or V, Mesh 20\u201340<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-substrate-card\">\n    <div class=\"pm-substrate-head composite\">\ud83d\udee9\ufe0f CFRP \/ Fiberglass Composite<\/div>\n    <div class=\"pm-substrate-body\">\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Primary structure<\/span><span class=\"pm-substrate-val\">20\u201330 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Secondary \/ fairings<\/span><span class=\"pm-substrate-val\">20\u201335 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Fibra de vidrio<\/span><span class=\"pm-substrate-val\">25\u201340 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Damage risk at<\/span><span class=\"pm-substrate-val\">&gt;40 PSI \u2014 fiber exposure<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Recommended media<\/span><span class=\"pm-substrate-val\">Type V Acrylic only, Mesh 30\u201350<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-substrate-card\">\n    <div class=\"pm-substrate-head mold\">\ud83d\udd27 Tool Steel (Mold \/ Die)<\/div>\n    <div class=\"pm-substrate-body\">\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">P20 (HRC 28\u201334)<\/span><span class=\"pm-substrate-val\">15\u201325 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">H13 (HRC 44\u201352)<\/span><span class=\"pm-substrate-val\">15\u201330 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">D2 \/ S7 (HRC 54+)<\/span><span class=\"pm-substrate-val\">20\u201335 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Damage risk at<\/span><span class=\"pm-substrate-val\">Ra creep \u2014 gradual, hard to see<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Recommended media<\/span><span class=\"pm-substrate-val\">Type V, Mesh 50\u201380<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-substrate-card\">\n    <div class=\"pm-substrate-head cast\">\ud83c\udfed Cast Iron \/ Cast Steel<\/div>\n    <div class=\"pm-substrate-body\">\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Standard range<\/span><span class=\"pm-substrate-val\">35\u201360 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Complex casting geometry<\/span><span class=\"pm-substrate-val\">35\u201350 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Simple surfaces<\/span><span class=\"pm-substrate-val\">45\u201365 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Damage risk at<\/span><span class=\"pm-substrate-val\">Pore opening if porosity present<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Recommended media<\/span><span class=\"pm-substrate-val\">Type II or III, Mesh 16\u201325<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-substrate-card\">\n    <div class=\"pm-substrate-head thin\">\ud83d\udc8e Plated \/ Coated Metal<\/div>\n    <div class=\"pm-substrate-body\">\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Electroless nickel plate<\/span><span class=\"pm-substrate-val\">12\u201320 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Hard chrome (intact)<\/span><span class=\"pm-substrate-val\">15\u201325 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Anodize (blast to clean)<\/span><span class=\"pm-substrate-val\">10\u201318 PSI<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Damage risk at<\/span><span class=\"pm-substrate-val\">Any excess \u2014 coating delamination<\/span><\/div>\n      <div class=\"pm-substrate-row\"><span class=\"pm-substrate-label\">Recommended media<\/span><span class=\"pm-substrate-val\">Type V Acrylic, Mesh 60\u201380<\/span><\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 6 \u2014 VARIABLES THAT INTERACT\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-variables\">Variables That Interact With Pressure<\/h2>\n\n<p>Pressure does not operate in isolation. Five other variables directly modify the effective impact energy delivered to the substrate at a given nozzle pressure. Understanding these interactions allows you to deliberately adjust the total process energy without touching the pressure dial \u2014 and explains why two operations running at &#8220;the same pressure&#8221; can produce radically different results.<\/p>\n\n<div class=\"pm-var-grid\">\n  <div class=\"pm-var-card\">\n    <span class=\"pm-var-icon\">\ud83c\udfaf<\/span>\n    <div class=\"pm-var-name\">Media Mesh Size<\/div>\n    <div class=\"pm-var-up\">\u2191 Coarser mesh \u2192 More energy per impact at same PSI<\/div>\n    <div class=\"pm-var-down\">\u2193 Finer mesh \u2192 Less energy per impact, more impacts per area<\/div>\n  <\/div>\n  <div class=\"pm-var-card\">\n    <span class=\"pm-var-icon\">\ud83d\udccf<\/span>\n    <div class=\"pm-var-name\">Standoff Distance<\/div>\n    <div class=\"pm-var-up\">\u2191 Closer standoff \u2192 Higher energy per impact (less air deceleration)<\/div>\n    <div class=\"pm-var-down\">\u2193 Greater standoff \u2192 Lower energy per impact, wider pattern<\/div>\n  <\/div>\n  <div class=\"pm-var-card\">\n    <span class=\"pm-var-icon\">\ud83d\udcd0<\/span>\n    <div class=\"pm-var-name\">Impingement Angle<\/div>\n    <div class=\"pm-var-up\">\u2191 More perpendicular (90\u00b0) \u2192 Maximum energy transfer<\/div>\n    <div class=\"pm-var-down\">\u2193 More oblique (45\u201360\u00b0) \u2192 Reduced energy, more tangential cutting<\/div>\n  <\/div>\n  <div class=\"pm-var-card\">\n    <span class=\"pm-var-icon\">\ud83d\udd29<\/span>\n    <div class=\"pm-var-name\">Nozzle Bore Size<\/div>\n    <div class=\"pm-var-up\">\u2191 Larger bore \u2192 More media volume, same velocity<\/div>\n    <div class=\"pm-var-down\">\u2193 Worn nozzle (+1\/16\u2033) \u2192 Lower velocity at same inlet pressure \u2014 hidden energy loss<\/div>\n  <\/div>\n  <div class=\"pm-var-card\">\n    <span class=\"pm-var-icon\">\ud83c\udfc3<\/span>\n    <div class=\"pm-var-name\">Nozzle Travel Speed<\/div>\n    <div class=\"pm-var-up\">\u2191 Slower movement \u2192 More impacts per unit area \u2014 higher cumulative energy<\/div>\n    <div class=\"pm-var-down\">\u2193 Faster movement \u2192 Fewer impacts per area \u2014 effectively reduces energy density<\/div>\n  <\/div>\n  <div class=\"pm-var-card\">\n    <span class=\"pm-var-icon\">\u23f1\ufe0f<\/span>\n    <div class=\"pm-var-name\">Dwell \/ Passes<\/div>\n    <div class=\"pm-var-up\">\u2191 More passes \u2192 Higher cumulative impact energy \u2014 can damage substrate even at low single-pass pressure<\/div>\n    <div class=\"pm-var-down\">\u2193 Single pass \u2192 Lowest cumulative energy \u2014 may be insufficient for thick coatings<\/div>\n  <\/div>\n<\/div>\n\n<div class=\"pm-callout pm-callout-green\">\n  <strong>The practical implication:<\/strong> When a process is producing insufficient coating removal at the minimum safe pressure, the correct response is not always to increase pressure. First evaluate whether increasing the number of passes, reducing standoff by 1\u20132 inches, or slowing nozzle travel speed can achieve the required strip rate at the current pressure. These adjustments increase effective energy delivery without the risk profile of a pressure increase \u2014 and they are reversible without re-qualification.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 7 \u2014 MESH AND PRESSURE\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-mesh\">How Mesh Size Changes Your Effective Pressure<\/h2>\n\n<p>Mesh size and pressure are partially interchangeable in terms of their effect on coating removal \u2014 both ultimately determine impact energy. A coarser mesh at lower pressure can deliver equivalent strip performance to a finer mesh at higher pressure. This interchangeability is a useful tool when you are constrained at one end: if you cannot increase pressure beyond a safe maximum, switching to a coarser mesh is the way to increase strip rate without increasing pressure.<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Scenario<\/th>\n        <th>Original Parameters<\/th>\n        <th>Adjusted Parameters<\/th>\n        <th>Net Effect<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Stripping slowly \u2014 can&#8217;t increase pressure (substrate limit)<\/td>\n        <td>Mesh 30, 30 PSI<\/td>\n        <td>Mesh 20, 30 PSI<\/td>\n        <td>Strip rate increases ~30\u201340%; same substrate impact per particle, more kinetic energy per larger particle. Monitor surface profile.<\/td>\n      <\/tr>\n      <tr>\n        <td>Substrate damage occurring \u2014 can&#8217;t reduce pressure more (strip floor)<\/td>\n        <td>Mesh 20, 35 PSI<\/td>\n        <td>Mesh 30, 35 PSI<\/td>\n        <td>Energy per impact reduced ~20\u201325%; same strip rate potential over more passes; substrate impact stress per event reduced.<\/td>\n      <\/tr>\n      <tr>\n        <td>Need finer surface finish after stripping<\/td>\n        <td>Mesh 20, 40 PSI (rough result)<\/td>\n        <td>Mesh 30\u201340, 30\u201335 PSI<\/td>\n        <td>Finer surface profile; longer strip time but cleaner substrate texture; better adhesion profile for thin-film coatings.<\/td>\n      <\/tr>\n      <tr>\n        <td>Precision surface finishing (mold, pre-plate)<\/td>\n        <td>Mesh 40, 20 PSI<\/td>\n        <td>Mesh 60\u201380, 12\u201318 PSI<\/td>\n        <td>Minimum possible impact energy; preserves surface finish; accepts significantly longer cycle time for quality-critical applications.<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p>The practical limit on this interchangeability is at the coarse end: very coarse media (Mesh 12\u201316) at low pressure can still cause mechanical damage through sheer particle mass even at low velocity. And at the fine end, very fine media at any practical pressure cannot generate enough impact energy to remove tenacious coatings. The mesh-pressure design space has real boundaries; the interchangeability works within the center of the envelope, not at the extremes.<\/p>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 8 \u2014 STANDOFF AND ANGLE\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-standoff\">Standoff Distance and Angle as Pressure Modifiers<\/h2>\n\n<p>Standoff distance and impingement angle are the two geometrical parameters that modify effective blast energy delivery independent of the pressure dial. They give the operator real-time control over local process intensity \u2014 the ability to increase or decrease energy delivery in specific areas without stopping to adjust the system.<\/p>\n\n<h3>Standoff Distance<\/h3>\n<p>A media particle leaving the nozzle at full velocity immediately begins decelerating due to air resistance. The kinetic energy available at impact is the launch energy minus the deceleration loss. This loss is proportional to distance \u2014 a particle at 6 inches from the nozzle has lost relatively little energy; the same particle at 14 inches has lost significantly more. The practical effect:<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Standoff Distance<\/th>\n        <th>Relative Impact Energy vs. 10\u2033 Reference<\/th>\n        <th>Blast Pattern Width<\/th>\n        <th>Best Use Case<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>4\u20136 inches<\/td>\n        <td>~120\u2013130% of reference<\/td>\n        <td>Very narrow, concentrated<\/td>\n        <td>Spot-treating stubborn contamination; deep recesses; requires very controlled nozzle movement<\/td>\n      <\/tr>\n      <tr>\n        <td>6\u20138 inches<\/td>\n        <td>~110\u2013120% of reference<\/td>\n        <td>Narrow-to-moderate<\/td>\n        <td>Detail work, corners, edges; higher strip rate applications where control is prioritized<\/td>\n      <\/tr>\n      <tr>\n        <td>8\u201310 inches<\/td>\n        <td>Reference (100%)<\/td>\n        <td>Moderado<\/td>\n        <td>Default for most applications; good balance of strip rate and pattern uniformity<\/td>\n      <\/tr>\n      <tr>\n        <td>10\u201312 inches<\/td>\n        <td>~85\u201390% of reference<\/td>\n        <td>Moderate-to-wide<\/td>\n        <td>Sensitive substrates needing reduced effective energy; thin aluminum; composite skins<\/td>\n      <\/tr>\n      <tr>\n        <td>12\u201316 inches<\/td>\n        <td>~70\u201380% of reference<\/td>\n        <td>Wide, diffuse<\/td>\n        <td>Maximum substrate protection; pre-anodize cleaning passes; very thin-wall parts<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<h3>Impingement Angle<\/h3>\n<p>At 90\u00b0 (perpendicular), all of the particle&#8217;s kinetic energy is directed normal to the surface \u2014 maximum energy transfer into the substrate-coating interface. As the angle decreases toward oblique, the normal component of energy decreases (less substrate impact) while the tangential component increases (more cutting\/shearing action along the surface). For most coating removal applications, 75\u201385\u00b0 provides the best combination of strip efficiency and substrate protection. For mold cleaning and surface finishing where the goal is removing surface contamination with minimum substrate impact, 60\u201375\u00b0 is preferred. Never blast perpendicular to polished surfaces \u2014 the pure normal impact at 90\u00b0 is most likely to alter Ra on precision surfaces.<\/p>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 9 \u2014 SIGNS OF TOO LOW\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-too-low\">Signs You Are Running Too Low<\/h2>\n\n<p>Under-pressure operation is safer than over-pressure, but it is still a problem \u2014 it wastes time, wastes media, and produces incomplete results that require re-work. Recognize these indicators before concluding that the media is wrong or the substrate is too difficult:<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Symptom<\/th>\n        <th>What It Looks Like<\/th>\n        <th>Diagnosis Confirmation<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Coating peeling rather than fracturing<\/td>\n        <td>Paint lifts at edges and peels in large sheets rather than fragmenting under impact \u2014 the blast stream is undercutting the coating at low-adhesion zones rather than fracturing it comprehensively<\/td>\n        <td>Increase pressure 5 PSI: if the mode shifts from peeling to fracturing\/powdering, you were under-pressure<\/td>\n      <\/tr>\n      <tr>\n        <td>Uneven coverage requiring many passes<\/td>\n        <td>Some areas clear after 2\u20133 passes; other areas of the same substrate with the same coating require 8\u201310 passes to clear \u2014 indicating marginal impact energy that only removes coating where adhesion happens to be lowest<\/td>\n        <td>Test strip at 5 PSI higher on a hidden area \u2014 if coverage uniformity improves, under-pressure confirmed<\/td>\n      <\/tr>\n      <tr>\n        <td>Media bouncing visibly off coating surface<\/td>\n        <td>At very low pressure, media impact is visible as particles ricocheting off the surface without cutting into the coating \u2014 the coating is not responding to the blast at all<\/td>\n        <td>Definitive visual confirmation of under-pressure; increase by 5\u20138 PSI and re-evaluate<\/td>\n      <\/tr>\n      <tr>\n        <td>Burnishing \/ polishing instead of removing<\/td>\n        <td>Soft coatings (e.g., flexible topcoats, some specialty primers) respond to very low blast pressure by polishing smooth rather than fragmenting \u2014 surface appears shinier and more uniform rather than being removed<\/td>\n        <td>Check surface with white rag \u2014 if rag picks up coating color, coating is still present but compressed rather than removed<\/td>\n      <\/tr>\n      <tr>\n        <td>Strip rate decreases progressively through a session<\/td>\n        <td>First 10 minutes of blast session produces good removal; removal rate drops noticeably over the session even though nothing changes \u2014 indicates media wear combined with marginal starting pressure, so as media degrades slightly the process falls below the effective strip threshold<\/td>\n        <td>Check nozzle bore (worn nozzle reduces effective velocity); run sieve check on media from pot<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 10 \u2014 SIGNS OF TOO HIGH\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-too-high\">Signs You Are Running Too High<\/h2>\n\n<p>Over-pressure is the more dangerous failure mode \u2014 the substrate damage it causes is often irreversible and may not be immediately apparent under normal inspection conditions. These are the early warning indicators that pressure has exceeded the substrate&#8217;s damage threshold:<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Symptom<\/th>\n        <th>What It Looks Like<\/th>\n        <th>Severity<\/th>\n        <th>Action<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Thin steel panel warping<\/td>\n        <td>Panel surface shows oil-can distortion detectable by palm sweep; visible waves or buckles in light reflection; straightedge reveals departure from flatness<\/td>\n        <td><span class=\"pm-badge pm-badge-red\">\ud83d\udd34 Critical<\/span><\/td>\n        <td>Stop immediately. Reduce pressure 10+ PSI. Re-qualify. Warped panels require metal straightening \u2014 expensive rework.<\/td>\n      <\/tr>\n      <tr>\n        <td>Substrate surface appears frosted \/ hazy after strip<\/td>\n        <td>Bare metal surface after coating removal shows a frosted, micro-roughened appearance more aggressive than expected for the media mesh size \u2014 indicates micro-erosion of the substrate surface, not just coating removal<\/td>\n        <td><span class=\"pm-badge pm-badge-red\">\ud83d\udd34 High<\/span><\/td>\n        <td>Measure Ra; if above the substrate specification maximum, reduce pressure 5 PSI and re-qualify on test area.<\/td>\n      <\/tr>\n      <tr>\n        <td>Aluminum surface discoloration (darkening)<\/td>\n        <td>Blasted aluminum shows uneven grey-to-dark discoloration in some areas that does not respond to compressed air blowoff \u2014 indicates surface smearing or mechanical working of the aluminum surface layer<\/td>\n        <td><span class=\"pm-badge pm-badge-red\">\ud83d\udd34 High<\/span><\/td>\n        <td>Reduce pressure immediately. This condition may compromise anodize adhesion. Clean with appropriate acid etch before proceeding to coating.<\/td>\n      <\/tr>\n      <tr>\n        <td>CFRP surface shows fiber texture \/ weave<\/td>\n        <td>After blast, the surface reveals the fiber weave pattern of the composite \u2014 epoxy matrix has been eroded exposing the reinforcing fibers. Even slight exposure indicates the resin\/fiber bond integrity is compromised.<\/td>\n        <td><span class=\"pm-badge pm-badge-red\">\ud83d\udd34 Critical<\/span><\/td>\n        <td>Stop immediately. Do not proceed. Notify engineering \u2014 NDI required to assess depth of fiber exposure. May require repair\/rework of the composite structure.<\/td>\n      <\/tr>\n      <tr>\n        <td>Media embedding visible on substrate (white specks)<\/td>\n        <td>White particles visible on the bare metal surface after blowing off \u2014 media fragments embedded in the substrate surface rather than fracturing cleanly and bouncing off<\/td>\n        <td><span class=\"pm-badge pm-badge-yellow\">\ud83d\udfe1 Medium<\/span><\/td>\n        <td>Reduce pressure. Reduce to more oblique angle (60\u201370\u00b0). Embedded media compromises coating adhesion and may cause coating failure in service.<\/td>\n      <\/tr>\n      <tr>\n        <td>Surface profile exceeds specification maximum<\/td>\n        <td>Testex replica tape or profilometer measurement shows surface roughness above the specified maximum Rz or Ra \u2014 excessive peak-to-valley depth for the intended coating system<\/td>\n        <td><span class=\"pm-badge pm-badge-yellow\">\ud83d\udfe1 Medium<\/span><\/td>\n        <td>Reduce pressure and\/or increase mesh fineness. A profile too deep for the coating system creates coating thickness deficiency at peak crowns and premature corrosion initiation.<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 11 \u2014 HOW TO QUALIFY\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-qualify\">How to Qualify a New Pressure Setting<\/h2>\n\n<p>Any time you are using a new pressure setting \u2014 new application, new substrate, new media type, or new operator \u2014 the setting must be qualified against the specific substrate and coating combination before committing to production work. Qualification is not a lengthy or expensive process, but it is non-negotiable for any substrate where damage cannot be reversed.<\/p>\n\n<div style=\"margin:28px 0\">\n  <div class=\"pm-qual-step\">\n    <div class=\"pm-qual-left\"><div class=\"pm-qual-dot\">1<\/div><div class=\"pm-qual-line\"><\/div><\/div>\n    <div class=\"pm-qual-body\">\n      <h4>Establish the Target Parameters Range<\/h4>\n      <p>Using the Master Reference Table (Section 4) and the substrate guide (Section 5), identify the applicable pressure range for your substrate and media type. Note both the minimum (lower bound of strip effectiveness) and maximum (upper bound for substrate protection). Your qualification will find the optimum starting point within this range.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-qual-step\">\n    <div class=\"pm-qual-left\"><div class=\"pm-qual-dot\">2<\/div><div class=\"pm-qual-line\"><\/div><\/div>\n    <div class=\"pm-qual-body\">\n      <h4>Prepare the Qualification Test Panel<\/h4>\n      <p>Use a representative sample of the actual substrate material and coating system \u2014 same alloy\/grade, same coating type and thickness, same adhesion profile as production parts. A 6 \u00d7 12 inch panel is sufficient for qualification. Mark three equal sections of the panel for testing at three different pressures.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-qual-step\">\n    <div class=\"pm-qual-left\"><div class=\"pm-qual-dot\">3<\/div><div class=\"pm-qual-line\"><\/div><\/div>\n    <div class=\"pm-qual-body\">\n      <h4>Blast the Lower-Bound Section First<\/h4>\n      <p>Set the nozzle inlet pressure to the lower bound of the applicable range (verified with the inline nozzle gauge under active blast conditions). Blast a 4 \u00d7 4 inch area of Section 1 at standardized nozzle technique: 8\u201310 inch standoff, 75\u201380\u00b0 angle, consistent overlapping passes. Record time to achieve complete coating removal. Inspect for substrate damage indicators. Measure Ra and surface profile.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-qual-step\">\n    <div class=\"pm-qual-left\"><div class=\"pm-qual-dot\">4<\/div><div class=\"pm-qual-line\"><\/div><\/div>\n    <div class=\"pm-qual-body\">\n      <h4>Step Up to the Mid-Range Section<\/h4>\n      <p>Increase pressure to the midpoint of the range (or to the upper bound if the lower-bound test produced no coating removal). Blast Section 2 with identical technique. Record strip time, inspect for substrate damage, measure Ra. Compare strip rate improvement against any substrate condition change vs. Section 1.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-qual-step\">\n    <div class=\"pm-qual-left\"><div class=\"pm-qual-dot\">5<\/div><div class=\"pm-qual-line\"><\/div><\/div>\n    <div class=\"pm-qual-body\">\n      <h4>Select the Qualified Operating Pressure<\/h4>\n      <p>The qualified operating pressure is the lowest pressure from the qualification test that achieves complete coating removal in an acceptable cycle time without any substrate damage indicators. If both the lower-bound and mid-range tests produce clean, damage-free results, use the lower-bound pressure \u2014 it provides maximum safety margin. If the lower-bound test produced incomplete removal, use the mid-range pressure. Document the qualified pressure, media type, mesh size, standoff, and angle as the process specification.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-qual-step\">\n    <div class=\"pm-qual-left\"><div class=\"pm-qual-dot\">6<\/div><div class=\"pm-qual-line\"><\/div><\/div>\n    <div class=\"pm-qual-body\">\n      <h4>Run the Production Verification Blast<\/h4>\n      <p>Blast the first production part or first production section at the qualified parameters with full inspection at the end. Verify that production results match the qualification test panel. Document the first-article inspection results and retain with the process specification. Re-qualify if any of the three defining variables change: substrate material\/grade, coating type\/thickness, or media specification.<\/p>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 12 \u2014 PRESSURE DRIFT\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-drift\">Pressure Drift: Why Your Setting Changes Without Touching the Dial<\/h2>\n\n<p>One of the most frustrating and least understood phenomena in blast operations is the degradation of process performance over time at a &#8220;fixed&#8221; pressure setting. The operator has not changed anything \u2014 the pot regulator reads the same number as on the qualification date \u2014 but strip rate has dropped, or surface results are inconsistent. The cause is almost always pressure drift: the actual nozzle inlet pressure has changed even though the control point reading has not. The four most common causes:<\/p>\n\n<p><strong>Nozzle wear:<\/strong> As the nozzle bore grows from wear, more air passes through the nozzle at the same inlet pressure \u2014 but at lower velocity because the larger bore produces lower pressure drop and therefore lower exit velocity per unit of airflow. A nozzle worn 1\/16 inch oversize can reduce particle velocity by 15\u201325% at the same pot regulator setting. The gauge reads the same; the substrate receives significantly less energy. Measure nozzle bore regularly and replace at the specified maximum wear limit.<\/p>\n\n<p><strong>Hose degradation:<\/strong> Blast hoses develop interior wear and internal collapse over time. A hose with reduced interior diameter increases pressure drop along its length, delivering less pressure to the nozzle inlet at the same pot regulator setting. Replace blast hoses annually in production operations or whenever kinking, exterior cracking, or reduced flexibility is observed.<\/p>\n\n<p><strong>Compressor capacity loss:<\/strong> Compressor output degrades over time due to worn cylinder seals, dirty air filters, and dryer system inefficiency. A compressor that initially delivered 100 CFM at 90 PSI may deliver only 80 CFM after two years of operation without maintenance \u2014 reducing available nozzle pressure at the same flow demand. Check compressor output quarterly with a CFM meter at the outlet.<\/p>\n\n<p><strong>Media size degradation:<\/strong> As media degrades through multiple reclaim cycles to a smaller average particle size, the pressure required to achieve the same strip rate increases \u2014 finer particles carry less kinetic energy at the same velocity. A process qualified with fresh Mesh 20 media operating at 35 PSI may require 40\u201342 PSI with the same media after 4 reclaim cycles to achieve the same strip rate. The media condition has effectively reduced the process energy below the minimum effective level, making it appear to the operator that &#8220;the pressure setting isn&#8217;t working anymore.&#8221;<\/p>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     SECTION 13 \u2014 TROUBLESHOOTING\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-troubleshoot\">Pressure Troubleshooting Guide<\/h2>\n\n<div class=\"pm-trouble\">\n  <h4>Process was working well; strip rate has declined without any parameter changes<\/h4>\n  <div class=\"pm-trouble-tags\">\n    <span class=\"pm-tc\">Cause: Nozzle wear; compressor capacity loss; media degradation<\/span>\n    <span class=\"pm-tf\">Fix: Check nozzle bore first \u2014 fastest and most common cause<\/span>\n  <\/div>\n  <p>Before adjusting any parameter, measure the nozzle bore with a pin gauge. If the bore is at or past the replacement limit, replace the nozzle and re-test before any other changes. If the nozzle is in-spec, verify actual FAD from the compressor and run a sieve analysis on the working media. These three checks cover 90% of unexplained strip rate decline cases. Only if all three check out as in-specification should you investigate hose condition, media moisture, or reconsider the process parameters themselves.<\/p>\n<\/div>\n\n<div class=\"pm-trouble\">\n  <h4>Compressor pressure drops and recovers cyclically during blast operation<\/h4>\n  <div class=\"pm-trouble-tags\">\n    <span class=\"pm-tc\">Cause: Compressor undersized for nozzle; receiver tank too small; air demand exceeds compressor FAD<\/span>\n    <span class=\"pm-tf\">Fix: Reduce nozzle bore size; increase compressor capacity; check for air leaks in system<\/span>\n  <\/div>\n  <p>Cyclic pressure drop during blasting (the pressure falls when the trigger is pulled and recovers when released) is the unmistakable signature of an undersized compressor. The compressor cannot sustain the FAD demanded by the nozzle, causing pressure to collapse until the compressor catches up. The only permanent fix is to match the compressor FAD to the nozzle CFM requirement \u2014 either by reducing the nozzle bore (if a smaller nozzle is acceptable for the application) or by upgrading the compressor. A larger receiver tank provides a buffer for short-duration demand spikes but does not solve the fundamental undersizing problem for sustained blast operations.<\/p>\n<\/div>\n\n<div class=\"pm-trouble\">\n  <h4>Nozzle pressure gauge reads correctly but blast stream looks weak \/ lacks impact<\/h4>\n  <div class=\"pm-trouble-tags\">\n    <span class=\"pm-tc\">Cause: Low media-to-air ratio in blast stream; bridging at metering valve; wet media clumping<\/span>\n    <span class=\"pm-tf\">Fix: Check media flow rate from pot; inspect and clean metering valve; moisture check<\/span>\n  <\/div>\n  <p>Nozzle pressure can be correct while blast performance is poor if the media-to-air ratio in the blast stream is too low. The pressure pushes air effectively but with insufficient media to carry impact energy to the surface. Check the media flow rate by briefly diverting the blast stream into a bucket \u2014 normal media flow should produce a visible, densely loaded stream. If the stream appears mostly air with sparse media, the metering valve may be partially closed or the pot media level may be too low. Refill if needed, and inspect and clean the metering valve orifice if flow remains low after refilling.<\/p>\n<\/div>\n\n<div class=\"pm-trouble\">\n  <h4>Substrate shows damage at the pressure that was previously safe \u2014 same substrate, same parameters<\/h4>\n  <div class=\"pm-trouble-tags\">\n    <span class=\"pm-tc\">Cause: Different substrate lot or grade than qualified; substrate condition changed (heat treated differently, thinner gauge); nozzle worn smaller<\/span>\n    <span class=\"pm-tf\">Fix: Verify substrate specification matches qualification material; re-qualify if material has changed<\/span>\n  <\/div>\n  <p>The most overlooked source of substrate damage &#8220;at previously safe parameters&#8221; is a material change in the substrate. Aluminum alloy 6061-T4 and 6061-T6 have different yield strengths and respond differently to the same blast parameters \u2014 as do different gauges of the nominally same specification steel. Verify that the current production material matches the qualification coupon in alloy, temper, and gauge. If the material specification has changed, the process qualification must be repeated \u2014 parameters from one material specification do not automatically transfer to another, even within the same alloy family.<\/p>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     FAQ\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"pr-faq\">Preguntas frecuentes<\/h2>\n\n<div itemscope itemtype=\"https:\/\/schema.org\/FAQPage\">\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">Why do aerospace specifications give such a narrow pressure range (e.g., 20\u201335 PSI) while automotive operators seem to use much higher pressures?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">The pressure range difference reflects the different consequences of substrate damage in each application. Aerospace aluminum structures are fatigue-critical \u2014 cyclic stress from flight loads means that even microscopic surface damage (micro-cracks, surface cold work, residual stress introduction) can initiate fatigue failures that progress over thousands of flight cycles and result in structural failure. The narrow aerospace pressure range is set to keep blast intensity below the threshold at which surface fatigue life is measurably reduced, which is verified through Almen strip testing and sometimes through coupon fatigue testing at qualification. Automotive panels, by contrast, are not fatigue-critical in the same way \u2014 a dented or even slightly warped body panel is a cosmetic and dimensional problem, not a safety-of-flight issue. Automotive operators can tolerate a wider operating window because the consequences of minor substrate over-blast are rework, not structural failure. The higher pressures sometimes used in automotive blast work would be completely unacceptable on aerospace aluminum \u2014 not because the aluminum is necessarily thinner (structural frames can be quite thick) but because the fatigue consequence is categorically different.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">Can I use the same pressure for all media mesh sizes, or does changing mesh require a pressure adjustment?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Changing mesh size requires re-evaluating pressure \u2014 they are not independent. A pressure setting that produces acceptable strip rate and surface profile with Mesh 20 media will typically produce over-aggressive results with the same pressure at Mesh 12 (larger, heavier particles carry more kinetic energy per particle) and under-effective results with the same pressure at Mesh 40 (smaller, lighter particles carry less kinetic energy per particle). When switching mesh size, use the new mesh size&#8217;s applicable pressure range from the reference tables in this article rather than the pressure that was working for the previous mesh. In general, switching to a coarser mesh should be accompanied by a pressure reduction of 5\u201310 PSI from the current setting; switching to a finer mesh may require a pressure increase of 5\u201310 PSI to maintain equivalent strip rate. Always qualify the new mesh-pressure combination on a test area before committing to production.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">Is there a simple field test to tell if my blast pressure is in the correct range before I do formal qualification?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Yes \u2014 the split test. Find a small, hidden area of the substrate with coating present. Blast a 2-inch square at your proposed starting pressure for 30 seconds with consistent technique, then inspect. A correct pressure produces a clean, uniformly stripped area with a consistently matte bare substrate surface \u2014 the coating should be completely removed, the bare surface should look uniform in texture, and there should be no gloss spots (remaining coating) or discoloration (substrate over-blast). If the coating is not completely removed, increase pressure by 5 PSI and repeat on an adjacent 2-inch area. If the substrate shows any discoloration, unusual texture, or visible roughness beyond what the media mesh would be expected to produce, reduce pressure by 5 PSI and repeat. The split test does not replace formal qualification with measurements \u2014 but it gets you to the right order of magnitude in 5 minutes before investing in detailed qualification work on a large test panel.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">What is the maximum safe pressure for plastic media blasting on carbon fiber composite?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">For carbon fiber reinforced polymer (CFRP) structures, the broadly accepted maximum nozzle inlet pressure for plastic media blasting is 40 PSI using Type V acrylic media at Mesh 30\u201340. Most established aerospace process specifications for composite depainting set working ranges of 20\u201335 PSI, with 40 PSI as an absolute upper limit that should not be approached without specific process qualification data demonstrating acceptable results on that exact composite layup and resin system. Above 40 PSI, the risk of eroding the epoxy matrix to expose carbon fibers becomes significant \u2014 and any fiber exposure represents structural damage to the composite that may not be visible under normal white-light inspection. Fiber exposure requires NDI (non-destructive inspection) to characterize, and potentially requires repair or replacement of the affected structure. If 40 PSI with Type V acrylic is insufficient to remove a particularly tenacious coating from CFRP, the correct response is not to increase blast pressure but to investigate chemical softening (application of a compatible paint stripper to the coating before blasting) or laser ablation for that specific coating type rather than exceeding the pressure limit for the substrate.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">My automotive customer specifies &#8220;media blast per MIL-P-85891A&#8221; without giving a specific pressure. What pressure should I use?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">MIL-P-85891A is a media specification standard \u2014 it defines the properties the plastic blast media must meet (hardness, density, moisture content, pH, particle size distribution) but does not specify blast operating parameters. When a customer references MIL-P-85891A without additional process parameters, they are specifying the media type and quality standard, not the operating conditions. For automotive panel stripping, the applicable pressure depends on the panel gauge and coating system \u2014 use the substrate-specific ranges from this article as your starting point (25\u201340 PSI for 18-gauge steel panels, 25\u201335 PSI for aluminum panels) and qualify the specific pressure for the customer&#8217;s substrate and coating combination. If the customer has additional requirements for surface profile (Rz or Ra specification) or substrate condition after stripping (e.g., no distortion, specific cleanliness standard), request that specification before beginning qualification work \u2014 it is much easier to qualify to a defined acceptance criterion than to work backward from a complaint that the surface is not what the customer expected.<\/p>\n    <\/div>\n  <\/div>\n\n<\/div>","protected":false},"excerpt":{"rendered":"<p>What Pressure Should You Use for Plastic Media Blasting? Blast  [&#8230;]<\/p>","protected":false},"author":1,"featured_media":12356,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,177,138],"tags":[],"class_list":["post-12342","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-material","category-resource"],"_links":{"self":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/12342","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/comments?post=12342"}],"version-history":[{"count":4,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/12342\/revisions"}],"predecessor-version":[{"id":12408,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/12342\/revisions\/12408"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/media\/12356"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/media?parent=12342"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/categories?post=12342"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/tags?post=12342"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}