{"id":12307,"date":"2026-02-26T05:27:22","date_gmt":"2026-02-26T05:27:22","guid":{"rendered":"https:\/\/hlh-js.com\/?p=12307"},"modified":"2026-03-02T07:08:44","modified_gmt":"2026-03-02T07:08:44","slug":"acrylic-type-v-plastic-media-for-sensitive-surfaces","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/de\/resource\/blog\/acrylic-type-v-plastic-media-for-sensitive-surfaces\/","title":{"rendered":"Acrylic (Type V) Plastic Media for Sensitive Surfaces"},"content":{"rendered":"<!-- ============================================================\n     CLUSTER ARTICLE #3 \u2014 WordPress Post Content\n     Title: Acrylic (Type V) Plastic Media for Sensitive Surfaces\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 .pm- 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.pm-science-grid{grid-template-columns:1fr}\n  .pm-verdict-grid{grid-template-columns:1fr}\n  .pm-stat-bar{grid-template-columns:repeat(2,1fr)}\n  .pm-stat-item{border-bottom:1px solid #e2e8f0}\n  .pm-stat-item:nth-child(even){border-right:none}\n}\n@media(max-width:420px){\n  .pm-param-grid{grid-template-columns:repeat(2,1fr)}\n  .pm-stat-bar{grid-template-columns:1fr 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>Acrylic (Type V) Plastic Media for Sensitive Surfaces<\/h1>\n<p>There is a category of surface finishing challenge where standard plastic blast media \u2014 even the substrate-friendly Type II urea \u2014 simply cannot be used without risking damage. Carbon fiber reinforced polymer structures. Thermoplastic injection-molded components. Polished mold tool cavities. Radome and antenna covers. In each of these applications, the question is not just &#8220;how do I remove this coating?&#8221; but &#8220;how do I remove it without altering, fracturing, or contaminating the substrate at the molecular level?&#8221;<\/p>\n\n<p>The answer, consistently, is <strong>Type V acrylic (PMMA) plastic blast media<\/strong>.<\/p>\n\n<p>Acrylic media is the softest, gentlest, and most substrate-protective abrasive in the plastic blast media family. It is also the least well understood \u2014 many operators know they need it for sensitive substrates but are unsure how it actually works, why it behaves differently from urea or melamine, and how to run it correctly to get reliable results without going through media charges too fast.<\/p>\n\n<p>This guide closes those gaps. We cover the physics of PMMA&#8217;s impact behavior, every sensitive-surface application where Type V acrylic is the right choice, precise process parameters for each scenario, storage and handling requirements, and the limits beyond which even acrylic is not gentle enough. For a broader comparison with Type II urea and Type III melamine, see: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/plastic-blast-media-types-compared-urea-vs-melamine-vs-acrylic\/\">Plastic Blast Media Types Compared: Urea vs Melamine vs Acrylic<\/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<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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     TABLE OF CONTENTS\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<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=\"#ac-what\">What Is Type V Acrylic Blast Media?<\/a><\/li>\n    <li><a href=\"#ac-science\">The Science: Why PMMA Behaves Differently<\/a><\/li>\n    <li><a href=\"#ac-properties\">Complete Physical &amp; Chemical Properties<\/a><\/li>\n    <li><a href=\"#ac-sensitive\">What Makes a Surface &#8220;Sensitive&#8221;?<\/a><\/li>\n    <li><a href=\"#ac-applications\">Application Deep Dives<\/a>\n      <ol>\n        <li><a href=\"#ac-cfrp\">CFRP &amp; Carbon Fiber Composites<\/a><\/li>\n        <li><a href=\"#ac-thermoplastic\">Thermoplastic Components<\/a><\/li>\n        <li><a href=\"#ac-fiberglass\">Fiberglass (FRP) Structures<\/a><\/li>\n        <li><a href=\"#ac-mold\">Polished Mold Tool Surfaces<\/a><\/li>\n        <li><a href=\"#ac-radome\">Radomes &amp; Composite Antenna Covers<\/a><\/li>\n        <li><a href=\"#ac-electronics\">Electronics Deflashing<\/a><\/li>\n      <\/ol>\n    <\/li>\n    <li><a href=\"#ac-parameters\">Optimal Blast Parameters by Application<\/a><\/li>\n    <li><a href=\"#ac-setup\">Process Qualification: Step-by-Step<\/a><\/li>\n    <li><a href=\"#ac-storage\">Storage, Handling &amp; Moisture Control<\/a><\/li>\n    <li><a href=\"#ac-reuse\">Maximizing Reuse Cycles<\/a><\/li>\n    <li><a href=\"#ac-warning\">Early Warning Signs of Over-Blasting<\/a><\/li>\n    <li><a href=\"#ac-limits\">The Limits of Acrylic: When Even Type V Isn&#8217;t Enough<\/a><\/li>\n    <li><a href=\"#ac-vs\">Acrylic vs Walnut Shell on Sensitive Substrates<\/a><\/li>\n    <li><a href=\"#ac-faq\">H\u00e4ufig gestellte Fragen<\/a><\/li>\n    <li><a href=\"#ac-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 WHAT IS IT\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=\"ac-what\">What Is Type V Acrylic Blast Media?<\/h2>\n\n<p>Type V acrylic blast media is manufactured from <strong>polymethyl methacrylate (PMMA)<\/strong> \u2014 the same base polymer used in Plexiglas, Lucite, and optical lenses \u2014 ground and screened to precise angular particle size distributions for use as a blasting abrasive. Unlike the Type II (urea) and Type III (melamine) varieties in the plastic blast media family, which are thermosetting resins that cure into rigid, brittle networks, PMMA is a <strong>thermoplastic<\/strong>: it remains re-meltable after forming, giving it a fundamentally different molecular structure and impact behavior.<\/p>\n\n<p>Under the MIL-P-85891A classification system that governs plastic blast media for defense and aerospace applications, acrylic media is designated <strong>Type V<\/strong>. It is the softest type in the standard&#8217;s five-type taxonomy, with a Mohs hardness of approximately 3.0 \u2014 lower than urea (~3.5) and meaningfully lower than melamine (~4.0). That half-point difference in Mohs hardness may sound trivial, but at the particle-substrate interface during a blast operation, it translates into a categorically different force transfer profile that determines whether sensitive substrates survive the process intact.<\/p>\n\n<div class=\"pm-stat-bar\">\n  <div class=\"pm-stat-item\">\n    <div class=\"pm-stat-value\">~3.0<\/div>\n    <div class=\"pm-stat-label\">Mohs Hardness (softest plastic blast media)<\/div>\n  <\/div>\n  <div class=\"pm-stat-item\">\n    <div class=\"pm-stat-value\">1.18<\/div>\n    <div class=\"pm-stat-label\">g\/cm\u00b3 True Density (lightest in class)<\/div>\n  <\/div>\n  <div class=\"pm-stat-item\">\n    <div class=\"pm-stat-value\">2\u20134<\/div>\n    <div class=\"pm-stat-label\">Reuse Cycles (with reclaim system)<\/div>\n  <\/div>\n  <div class=\"pm-stat-item\">\n    <div class=\"pm-stat-value\">&lt;0.3<\/div>\n    <div class=\"pm-stat-label\">mil Surface Profile on Aluminum<\/div>\n  <\/div>\n  <div class=\"pm-stat-item\">\n    <div class=\"pm-stat-value\">15\u201345<\/div>\n    <div class=\"pm-stat-label\">PSI Typical Operating Pressure Range<\/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 2 \u2014 THE SCIENCE\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=\"ac-science\">The Science: Why PMMA Behaves Differently<\/h2>\n\n<p>The performance distinction between acrylic and thermosetting plastic blast media is not just a matter of degree \u2014 it is a difference in fundamental failure mode. Understanding this explains every practical difference you observe in blast cabinet performance.<\/p>\n\n<div class=\"pm-science-grid\">\n  <div class=\"pm-science-card\">\n    <h4 class=\"thermo\">\ud83d\udd34 Thermosetting Resins (Urea &amp; Melamine)<\/h4>\n    <p>Urea and melamine are three-dimensionally cross-linked polymer networks. Once cured, the chains cannot slide or reorient relative to each other. When a particle impacts a surface, the entire energy of the collision is absorbed in a single, near-instantaneous event. The cross-linked network cannot redistribute that stress \u2014 it fractures catastrophically along the path of least resistance through the particle. This <strong>brittle fracture<\/strong> concentrates force at sharp angular edges, maximizing cutting action on coatings. The same concentrated force, however, is what makes these media types risky on fragile substrates: the shockwave from each fracture event radiates into the substrate surface at peak intensity.<\/p>\n  <\/div>\n  <div class=\"pm-science-card\">\n    <h4 class=\"plastic\">\ud83d\udfe2 PMMA Thermoplastic (Acrylic Type V)<\/h4>\n    <p>PMMA consists of long polymer chains with no cross-links between them. On impact, the chains can locally slide and reorient before the particle fractures \u2014 a brief period of <strong>viscoelastic deformation<\/strong> that absorbs and spreads the collision energy over a slightly longer time interval and larger contact area. This micro-deformation acts as a natural buffer: the peak stress transmitted to the substrate is measurably lower than for an equivalent thermosetting particle at the same velocity. PMMA still fractures \u2014 it is still a brittle material at macro scale \u2014 but the energy delivery to the substrate surface is gentler, more distributed, and less likely to initiate crack propagation in sensitive materials like carbon fiber or thin polymer matrices.<\/p>\n  <\/div>\n<\/div>\n\n<h3>The Density Advantage<\/h3>\n<p>PMMA&#8217;s true particle density of approximately 1.18 g\/cm\u00b3 is meaningfully lower than urea&#8217;s ~1.50 g\/cm\u00b3 and melamine&#8217;s ~1.52 g\/cm\u00b3. Since kinetic energy = \u00bdmv\u00b2, a lighter particle traveling at the same velocity carries less kinetic energy \u2014 and therefore delivers less impact force to the substrate per particle. At identical blast pressure settings, Type V acrylic particles arrive at the surface with roughly 20\u201325% less kinetic energy than equivalent-size urea particles. Combined with the viscoelastic deformation buffer, this makes the total substrate impact stress for acrylic significantly lower than the raw Mohs hardness comparison alone would suggest.<\/p>\n\n<div class=\"pm-callout pm-callout-blue\">\n  <strong>Key insight:<\/strong> Acrylic media is gentler than its Mohs hardness suggests, because hardness alone does not capture the full impact energy picture. The lower density and thermoplastic deformation behavior both reduce effective substrate stress, making Type V acrylic suitable for surfaces that would be damaged by any thermosetting abrasive \u2014 even at the same nominal hardness.\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 PROPERTIES\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=\"ac-properties\">Complete Physical &amp; Chemical Properties<\/h2>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr><th>Property<\/th><th>Value \/ Specification<\/th><th>Practical Significance<\/th><\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Resin Chemistry<\/td>\n        <td>Polymethyl methacrylate (PMMA), thermoplastic<\/td>\n        <td>Viscoelastic deformation on impact; lower peak substrate stress vs. thermosetting types<\/td>\n      <\/tr>\n      <tr>\n        <td>MIL-SPEC Designation<\/td>\n        <td>MIL-P-85891A, Type V<\/td>\n        <td>Required for qualified CFRP and composite depaint processes on defense aircraft<\/td>\n      <\/tr>\n      <tr>\n        <td>Mohs-H\u00e4rte<\/td>\n        <td>~3.0<\/td>\n        <td>Below virtually all structural metal alloys; near the lower bound for effective coating removal<\/td>\n      <\/tr>\n      <tr>\n        <td>True Particle Density<\/td>\n        <td>~1.18 g\/cm\u00b3<\/td>\n        <td>Lowest density of any common plastic blast media; less kinetic energy per particle at equal velocity<\/td>\n      <\/tr>\n      <tr>\n        <td>Sch\u00fcttdichte<\/td>\n        <td>~45\u201352 lb\/ft\u00b3 (720\u2013830 kg\/m\u00b3)<\/td>\n        <td>Lighter charge weight vs. urea\/melamine; affects hopper sizing and media flow calibration<\/td>\n      <\/tr>\n      <tr>\n        <td>Partikelform<\/td>\n        <td>Sub-angular to irregular<\/td>\n        <td>Less aggressive cutting geometry than thermosetting types; reduces fiber scoring risk on CFRP<\/td>\n      <\/tr>\n      <tr>\n        <td>Farbe<\/td>\n        <td>Clear to translucent white<\/td>\n        <td>Translucency allows visual inspection of media charge quality; contamination visible as cloudiness or darkening<\/td>\n      <\/tr>\n      <tr>\n        <td>Available Mesh Sizes<\/td>\n        <td>20, 30, 40, 50, 60, 80<\/td>\n        <td>Finer range than urea\/melamine; coarser grades (Mesh 12, 16) not typically produced in Type V<\/td>\n      <\/tr>\n      <tr>\n        <td>Moisture Absorption (24h)<\/td>\n        <td>~0.3% by weight (ASTM D570)<\/td>\n        <td>Higher than thermosetting types; requires sealed storage and moisture management protocol<\/td>\n      <\/tr>\n      <tr>\n        <td>pH (10% aqueous slurry)<\/td>\n        <td>6.5\u20138.0 (near-neutral)<\/td>\n        <td>No alkaline stress corrosion risk on aluminum; safe for all common metal substrates<\/td>\n      <\/tr>\n      <tr>\n        <td>Heat Deflection Temperature<\/td>\n        <td>~185\u2013205\u00b0F (85\u201396\u00b0C)<\/td>\n        <td>Media softens above this range; do not use in high-temperature blast environments or on hot substrates<\/td>\n      <\/tr>\n      <tr>\n        <td>Solvent Resistance<\/td>\n        <td>Moderate (attacked by ketones, esters, chlorinated solvents)<\/td>\n        <td>Do not clean blast cabinets or media with MEK, acetone, or chlorinated solvents when acrylic media is in circuit<\/td>\n      <\/tr>\n      <tr>\n        <td>Typical Reuse Cycles<\/td>\n        <td>2\u20134 passes (with reclaim)<\/td>\n        <td>Lower than urea (3\u20136) and melamine (4\u20138) due to thermoplastic fragmentation behavior<\/td>\n      <\/tr>\n      <tr>\n        <td>Surface Profile Produced<\/td>\n        <td>&lt;0.1\u20130.5 mil (2.5\u201312.5 \u00b5m) on aluminum<\/td>\n        <td>Near-zero profile capability; suitable for the most demanding re-prime and bonding specifications<\/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 4 \u2014 WHAT MAKES A SURFACE \"SENSITIVE\"\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=\"ac-sensitive\">What Makes a Surface &#8220;Sensitive&#8221;?<\/h2>\n\n<p>Not every substrate that requires gentle handling qualifies as &#8220;sensitive&#8221; in the blast media selection context. The term has specific technical meaning: a surface is sensitive when one or more of the following conditions apply, and any of them triggers the need for Type V acrylic over harder alternatives:<\/p>\n\n<div class=\"pm-signal-grid\">\n  <div class=\"pm-signal-card\">\n    <div class=\"pm-signal-icon\">\ud83e\uddf5<\/div>\n    <div class=\"pm-signal-body\">\n      <h4>Fiber-Reinforced Matrix<\/h4>\n      <p>Any substrate where fibers (carbon, glass, aramid) are embedded in a polymer matrix. Abrasive impact can sever surface fibers or drive crack propagation between fibers and matrix \u2014 damage that is invisible externally but degrades structural properties.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-signal-card\">\n    <div class=\"pm-signal-icon\">\ud83d\udd32<\/div>\n    <div class=\"pm-signal-body\">\n      <h4>Thin Wall \/ Low Stiffness<\/h4>\n      <p>Parts where the substrate itself has low resistance to deflection under localized impact load. Thin thermoplastic housings, sandwich panel skins, and thin-walled composite shells can flex on impact in ways that cause delamination or stress-whiten the polymer matrix.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-signal-card\">\n    <div class=\"pm-signal-icon\">\ud83d\udd2c<\/div>\n    <div class=\"pm-signal-body\">\n      <h4>Dimensional Criticality<\/h4>\n      <p>Surfaces where any measurable material removal from the substrate itself \u2014 even sub-mil \u2014 would violate dimensional tolerances. Injection mold cavity surfaces, precision optical components, and tight-tolerance machined features fall into this category.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-signal-card\">\n    <div class=\"pm-signal-icon\">\ud83d\udce1<\/div>\n    <div class=\"pm-signal-body\">\n      <h4>RF \/ Electromagnetic Transparency<\/h4>\n      <p>Radomes and antenna covers must maintain precise electromagnetic transmission characteristics. Physical surface alteration \u2014 even micro-scale profiling \u2014 can shift dielectric properties and degrade radar or communications performance.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-signal-card\">\n    <div class=\"pm-signal-icon\">\u26a1<\/div>\n    <div class=\"pm-signal-body\">\n      <h4>Embedded Conductors<\/h4>\n      <p>Electronic substrates with conductor traces, bond pads, or surface-mount components where abrasive impact could displace, damage, or short conductors. Deflashing of molded electronic parts requires controlled, gentle abrasive action.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-signal-card\">\n    <div class=\"pm-signal-icon\">\ud83d\udc8e<\/div>\n    <div class=\"pm-signal-body\">\n      <h4>Polished or Optical-Quality Finish<\/h4>\n      <p>Surfaces with controlled Ra values below 16 \u00b5in (0.4 \u00b5m) \u2014 mirror-polished mold cavities, optical elements, precision bearing surfaces \u2014 where any abrasive roughening would be functionally unacceptable.<\/p>\n    <\/div>\n  <\/div>\n<\/div>\n\n<div class=\"pm-callout pm-callout-warn\">\n  <strong>Important:<\/strong> &#8220;Sensitive&#8221; is not the same as &#8220;expensive&#8221; or &#8220;important.&#8221; A high-value steel component that is dimensionally robust is not sensitive to blast media in the technical sense. Conversely, an inexpensive thermoplastic housing is extremely sensitive and requires Type V acrylic regardless of its unit cost.\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 APPLICATIONS\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=\"ac-applications\">Application Deep Dives<\/h2>\n\n<p>Type V acrylic plastic media is the established solution for each of the following application categories. Each presents unique substrate sensitivities and process requirements:<\/p>\n\n\n<div class=\"pm-app-block\" id=\"ac-cfrp\">\n  <div class=\"pm-app-tag\">\u2708\ufe0f Application 01<\/div>\n  <h3>CFRP &amp; Carbon Fiber Composite Structures<\/h3>\n  <p>Carbon fiber reinforced polymer is the most demanding substrate in the plastic blast media world. CFRP derives its structural performance from the continuous carbon fiber reinforcement bonded within the polymer matrix \u2014 typically an epoxy resin system. The two failure modes that matter in blast operations are <strong>fiber severance<\/strong> (abrasive particles cutting through surface fibers, reducing load-carrying cross-section) and <strong>interlaminar delamination<\/strong> (shockwave energy propagating between plies and separating the matrix-fiber bond).<\/p>\n  <p>Type V acrylic is the only plastic blast media type that consistently avoids both failure modes at practical coating removal pressures. Its lower kinetic energy delivery, combined with the sub-angular particle shape&#8217;s reduced cutting geometry, strips paint from CFRP surfaces without driving crack propagation into the fiber architecture. The key operative word is &#8220;consistently&#8221; \u2014 urea can be used on CFRP at very low pressures (15\u201325 PSI) in some process specifications, but the margin for error is extremely narrow, and any equipment variation (worn nozzle, pressure surge, reduced standoff) pushes the process into the damage zone. Acrylic provides a wider, more forgiving process window.<\/p>\n  <p>Critical applications include: aircraft control surface depaint, composite fairing maintenance, CFRP fuselage panel stripping, nacelle acoustic liner cleaning, and repair bond surface preparation on structural composite assemblies.<\/p>\n  <div class=\"pm-app-params\">\n    <strong>Recommended Parameters:<\/strong> Type V Acrylic, Mesh 30\u201350 \u00b7 Pressure: 20\u201340 PSI \u00b7 Standoff: 8\u201312 inches \u00b7 Impingement angle: 60\u201380\u00b0 (avoid 90\u00b0 perpendicular on surface fiber layers) \u00b7 Nozzle travel speed: continuous, no dwell \u00b7 Watch for: surface fiber whitening as the first sign of over-blasting\n  <\/div>\n<\/div>\n\n\n<div class=\"pm-app-block\" id=\"ac-thermoplastic\">\n  <div class=\"pm-app-tag\">\ud83c\udfed Application 02<\/div>\n  <h3>Thermoplastic Injection-Molded Components<\/h3>\n  <p>Thermoplastic parts \u2014 ABS housings, polycarbonate covers, nylon structural components, polyester panels \u2014 present a different sensitivity profile from composites. The risk here is not fiber damage but <strong>stress whitening<\/strong> (localized yielding of the polymer chains that creates visible opacity), <strong>surface crazing<\/strong> (micro-crack networks initiated by impact stress), and <strong>dimensional alteration<\/strong> from abrasive material removal of the polymer surface itself.<\/p>\n  <p>The scenario where acrylic blast media is most commonly applied to thermoplastics is <strong>paint stripping for rework<\/strong>. A painted thermoplastic housing that has been painted the wrong color, has a cosmetic defect, or needs to be stripped for re-use can be returned to bare substrate using Type V acrylic at low pressure \u2014 something that would be impossible with urea (which would gouge the thermoplastic surface) or any mineral abrasive (which would destroy it entirely).<\/p>\n  <p>The process must be carefully qualified by polymer type. Amorphous polymers (ABS, polycarbonate, PMMA itself) are generally more sensitive to stress cracking than semi-crystalline polymers (nylon, polypropylene, PEEK) and require lower blast pressures and finer mesh. Always test on a representative coupon of the exact resin grade before committing to production.<\/p>\n  <div class=\"pm-app-params\">\n    <strong>Recommended Parameters:<\/strong> Type V Acrylic, Mesh 40\u201360 \u00b7 Pressure: 15\u201330 PSI \u00b7 Standoff: 10\u201314 inches \u00b7 Impingement angle: 60\u201375\u00b0 \u00b7 Note: Reduce pressure for amorphous polymers (ABS, PC); semi-crystalline polymers (PA, PP) tolerate slightly higher pressure \u00b7 Monitor: surface gloss change and stress whitening under angled raking light during qualification\n  <\/div>\n<\/div>\n\n\n<div class=\"pm-app-block\" id=\"ac-fiberglass\">\n  <div class=\"pm-app-tag\">\ud83d\udea4 Application 03<\/div>\n  <h3>Fiberglass (FRP) Structures<\/h3>\n  <p>Glass fiber reinforced polymer \u2014 the material of boat hulls, wind turbine blades, sporting equipment, and automotive body panels \u2014 shares some sensitivity characteristics with CFRP but is generally more forgiving. The glass fiber bundles embedded in polyester or vinyl ester resin matrices are less prone to individual fiber severance than carbon fiber, and the matrix materials are typically tougher than aerospace-grade epoxy systems.<\/p>\n  <p>However, FRP surfaces still require careful media selection for two reasons. First, excessive blast energy can <strong>expose the woven or chopped fiber mat<\/strong> at the surface, which would be unacceptable before repainting (gelcoat or primer will not bridge the fiber texture without additional filling). Second, older marine FRP structures may have osmotic blistering or delaminated gelcoat layers that can propagate inward if over-blasted.<\/p>\n  <p>For stripping antifouling paint from fiberglass boat hulls \u2014 one of the largest volume applications of acrylic blast media in the marine sector \u2014 Type V acrylic at Mesh 30\u201340 and 25\u201340 PSI consistently achieves clean gelcoat surfaces without fiber exposure when operated by trained personnel. The ability to process complex hull shapes in situ, without the chemical waste streams of traditional paint stripping, makes this an economically and environmentally attractive alternative to chemical stripping or mechanical sanding.<\/p>\n  <div class=\"pm-app-params\">\n    <strong>Recommended Parameters:<\/strong> Type V Acrylic, Mesh 30\u201350 \u00b7 Pressure: 25\u201340 PSI \u00b7 Standoff: 8\u201312 inches \u00b7 Impingement angle: 60\u201380\u00b0 \u00b7 Watch for: fiber texture appearing through gelcoat as a sign of excessive material removal \u00b7 Note: heavier antifouling buildup (&gt;5 coats) may require multiple light passes rather than a single high-pressure pass\n  <\/div>\n<\/div>\n\n\n<div class=\"pm-app-block\" id=\"ac-mold\">\n  <div class=\"pm-app-tag\">\ud83d\udd27 Application 04<\/div>\n  <h3>Polished Mold Tool Surfaces<\/h3>\n  <p>Injection mold tool cavities represent one of the most dimensionally critical applications for plastic blast media. A production mold can represent hundreds of thousands of dollars in tooling investment and must maintain cavity dimensions within microns to produce acceptable parts. Carbon deposits, release agent buildup, and polymer degradation residue accumulate on mold surfaces over production cycles and reduce surface quality and part release performance \u2014 but conventional cleaning methods (steel brushes, abrasive polishing compounds, chemical cleaners) either risk dimensional change or require time-consuming disassembly.<\/p>\n  <p>Type V acrylic blast media at fine mesh sizes (Mesh 50\u201380) and low pressures (15\u201325 PSI) provides an effective in-situ cleaning solution. The acrylic particles remove surface contamination without measurably altering the polished steel surface beneath. The process can often be performed with the mold at temperature (below 180\u00b0F \/ 82\u00b0C, the acrylic media&#8217;s heat deflection limit), reducing cleaning downtime.<\/p>\n  <p>The critical qualification requirement is establishing baseline surface roughness (Ra) measurements before and after the first cleaning cycle to confirm that the process is not progressively altering the tool surface. If Ra measurements show any upward trend across multiple cleaning cycles, either reduce pressure, increase mesh fineness, or investigate whether the cleaning interval needs to be shortened to reduce contamination buildup per cleaning event.<\/p>\n  <div class=\"pm-app-params\">\n    <strong>Recommended Parameters:<\/strong> Type V Acrylic, Mesh 50\u201380 \u00b7 Pressure: 15\u201325 PSI \u00b7 Standoff: 6\u201310 inches \u00b7 Impingement angle: 60\u201385\u00b0 (adjust for cavity geometry) \u00b7 Measure Ra before first use and after every 5th cleaning cycle \u00b7 Note: Do not use acrylic media in molds that have been treated with solvent-based release agents \u2014 residual ketone or ester solvents will accelerate acrylic media breakdown\n  <\/div>\n<\/div>\n\n\n<div class=\"pm-app-block\" id=\"ac-radome\">\n  <div class=\"pm-app-tag\">\ud83d\udce1 Application 05<\/div>\n  <h3>Radomes &amp; Composite Antenna Covers<\/h3>\n  <p>Aircraft radomes \u2014 the fiberglass, CFRP, or Nomex honeycomb sandwich structures that house weather radar and communications antennas \u2014 are among the most technically demanding depaint applications in aviation maintenance. Their sensitivity is dual-natured: the composite substrate requires gentle abrasive action, and the electromagnetic transparency characteristics of the structure must be preserved within tight tolerances after any surface treatment.<\/p>\n  <p>Radomes are constructed with specific wall thicknesses and dielectric properties calculated to minimize signal attenuation at designated radar frequency bands. Any physical alteration of the surface \u2014 including micro-scale profiling \u2014 can shift the effective dielectric constant of the surface layer and alter the transmission spectrum. For this reason, radome depaint processes typically specify Type V acrylic at the finest practical mesh size and lowest effective pressure, with mandatory electrical testing (transmission loss and boresight error measurement) after any blast operation to confirm the radome remains within performance specification.<\/p>\n  <p>Most major commercial and military aircraft maintenance programs have qualified Type V acrylic blast processes for their specific radome constructions. If your organization is developing a new radome depaint process, expect an extensive process qualification phase including environmental testing (temperature cycling, humidity exposure) after blast treatment to confirm that the process has not introduced any latent delamination or matrix microcracking that could propagate in service.<\/p>\n  <div class=\"pm-app-params\">\n    <strong>Recommended Parameters:<\/strong> Type V Acrylic, Mesh 40\u201360 \u00b7 Pressure: 15\u201330 PSI \u00b7 Standoff: 10\u201314 inches \u00b7 Impingement angle: 60\u201370\u00b0 \u00b7 Mandatory post-blast: electrical transmission testing per applicable radome maintenance manual \u00b7 Note: Never use Type II or Type III media on bare radome skins without explicit process engineering approval\n  <\/div>\n<\/div>\n\n\n<div class=\"pm-app-block\" id=\"ac-electronics\">\n  <div class=\"pm-app-tag\">\u26a1 Application 06<\/div>\n  <h3>Electronics Deflashing<\/h3>\n  <p>After injection molding of thermoplastic or thermoset electronic components \u2014 connector housings, IC packages, sensor bodies, relay cases \u2014 residual flash at parting lines must be removed consistently and without damage to conductor traces, bond wires, or molded-in features. Traditional deflashing methods (hand trimming, cryogenic tumbling, vibratory finishing) each have limitations in throughput, consistency, or access to complex geometries.<\/p>\n  <p>Type V acrylic media in a controlled blast deflashing system \u2014 typically a dedicated automated cabinet with part fixturing and controlled nozzle sweep \u2014 provides precise, repeatable flash removal on small electronic components without risking conductor damage. The key process variables are blast pressure (kept very low, often 15\u201325 PSI) and nozzle distance, which must be consistent across all part surfaces to prevent variable flash removal depths.<\/p>\n  <p>For high-volume electronic component deflashing, cryogenic systems (where parts are cooled to embrittlement temperature before blast exposure) are frequently combined with Type V acrylic media \u2014 the cryogenic embrittlement makes the flash remove cleanly at lower blast energies, further reducing substrate stress risk. At ambient temperature, flash on flexible polymers may require higher pressures to achieve clean removal, potentially pushing the process toward substrate contact \u2014 cryogenic conditioning is the preferred solution when ambient-temperature deflashing cannot achieve adequate results without substrate risk.<\/p>\n  <div class=\"pm-app-params\">\n    <strong>Recommended Parameters:<\/strong> Type V Acrylic, Mesh 50\u201380 \u00b7 Pressure: 15\u201325 PSI (ambient); 10\u201320 PSI (cryogenic) \u00b7 Standoff: 4\u20138 inches (short for precision) \u00b7 Automated fixturing preferred for consistency \u00b7 Post-process: electrical continuity and visual inspection under 10\u00d7 magnification \u00b7 See: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/using-plastic-media-for-electronics-deflashing\/\">Using Plastic Media for Electronics Deflashing<\/a>\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 PARAMETERS\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=\"ac-parameters\">Optimal Blast Parameters by Application<\/h2>\n\n<p>The following consolidates recommended parameters for the six primary Type V acrylic applications into a single reference table:<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Anmeldung<\/th>\n        <th>Mesh Size<\/th>\n        <th>Pressure (PSI)<\/th>\n        <th>Standoff (in)<\/th>\n        <th>Angle (\u00b0)<\/th>\n        <th>Key Risk to Monitor<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>CFRP \/ Carbon Fiber Composites<\/td>\n        <td>30\u201350<\/td>\n        <td>20\u201340<\/td>\n        <td>8\u201312<\/td>\n        <td>60\u201380\u00b0<\/td>\n        <td>Fiber whitening, delamination<\/td>\n      <\/tr>\n      <tr>\n        <td>Thermoplastic Components<\/td>\n        <td>40\u201360<\/td>\n        <td>15\u201330<\/td>\n        <td>10\u201314<\/td>\n        <td>60\u201375\u00b0<\/td>\n        <td>Stress whitening, crazing<\/td>\n      <\/tr>\n      <tr>\n        <td>Fiberglass (FRP) Hull \/ Panel<\/td>\n        <td>30\u201350<\/td>\n        <td>25\u201340<\/td>\n        <td>8\u201312<\/td>\n        <td>60\u201380\u00b0<\/td>\n        <td>Fiber mat exposure<\/td>\n      <\/tr>\n      <tr>\n        <td>Polished Mold Tool Surfaces<\/td>\n        <td>50\u201380<\/td>\n        <td>15\u201325<\/td>\n        <td>6\u201310<\/td>\n        <td>60\u201385\u00b0<\/td>\n        <td>Ra increase, surface haze<\/td>\n      <\/tr>\n      <tr>\n        <td>Radomes \/ Antenna Covers<\/td>\n        <td>40\u201360<\/td>\n        <td>15\u201330<\/td>\n        <td>10\u201314<\/td>\n        <td>60\u201370\u00b0<\/td>\n        <td>Dielectric property shift<\/td>\n      <\/tr>\n      <tr>\n        <td>Electronics Deflashing (ambient)<\/td>\n        <td>50\u201380<\/td>\n        <td>15\u201325<\/td>\n        <td>4\u20138<\/td>\n        <td>70\u201390\u00b0<\/td>\n        <td>Conductor exposure, incomplete removal<\/td>\n      <\/tr>\n      <tr>\n        <td>Electronics Deflashing (cryogenic)<\/td>\n        <td>50\u201380<\/td>\n        <td>10\u201320<\/td>\n        <td>4\u20138<\/td>\n        <td>70\u201390\u00b0<\/td>\n        <td>Part thermal shock during transition<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<div class=\"pm-callout pm-callout-warn\">\n  <strong>Universal rule for Type V acrylic:<\/strong> Always start at the low end of every parameter range and work upward incrementally on qualification coupons. The gentleness of acrylic media is only an advantage if it actually achieves adequate coating removal \u2014 if it does not, the correct response is to incrementally increase pressure or move to a coarser mesh, not to switch to a harder media type, unless process qualification testing confirms no other option is viable.\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 PROCESS QUALIFICATION\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=\"ac-setup\">Process Qualification: Step-by-Step<\/h2>\n\n<p>Because Type V acrylic is used precisely on the substrates where blast damage is most consequential, process qualification is not optional. Here is the standard qualification sequence:<\/p>\n\n<div class=\"pm-process\">\n\n  <div class=\"pm-process-step\">\n    <div class=\"pm-process-left\">\n      <div class=\"pm-process-dot\">1<\/div>\n      <div class=\"pm-process-line\"><\/div>\n    <\/div>\n    <div class=\"pm-process-body\">\n      <h4>Establish Baseline Measurements<\/h4>\n      <p>Before blasting any qualification coupon, characterize the baseline substrate condition. For composites: photograph surface under raking light, document any existing fiber damage or surface anomalies. For metals: measure Ra with a profilometer. For mold tools: take Ra measurements at multiple cavity locations. For radomes: record transmission loss and boresight error at the operating frequency band. These baselines are your reference against which post-blast measurements will be compared.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-process-step\">\n    <div class=\"pm-process-left\">\n      <div class=\"pm-process-dot\">2<\/div>\n      <div class=\"pm-process-line\"><\/div>\n    <\/div>\n    <div class=\"pm-process-body\">\n      <h4>Prepare Representative Coupons<\/h4>\n      <p>Qualification coupons must be the same material, temper, layup, and surface condition as production parts \u2014 not similar or equivalent. For CFRP, this means the same fiber orientation, resin system, cure cycle, and ply count. For thermoplastics, the same resin grade, wall thickness, and surface finish. Generic coupons from a different source or process will give misleading qualification data.<\/p>\n      <p class=\"pm-tip\">Prepare at least 5 coupons per parameter set \u2014 one for each of the planned parameter levels you intend to test, plus two extras for repeat testing if initial results are borderline.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-process-step\">\n    <div class=\"pm-process-left\">\n      <div class=\"pm-process-dot\">3<\/div>\n      <div class=\"pm-process-line\"><\/div>\n    <\/div>\n    <div class=\"pm-process-body\">\n      <h4>Blast at Conservative Starting Parameters<\/h4>\n      <p>Begin at the lowest pressure and finest mesh in the applicable range from the parameter table above. Blast a single pass across the coupon, maintaining consistent standoff and travel speed. Document all settings precisely, including nozzle bore diameter, nozzle-to-work angle, and travel speed estimate.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-process-step\">\n    <div class=\"pm-process-left\">\n      <div class=\"pm-process-dot\">4<\/div>\n      <div class=\"pm-process-line\"><\/div>\n    <\/div>\n    <div class=\"pm-process-body\">\n      <h4>Inspect and Measure After Each Pass<\/h4>\n      <p>After each blast pass, inspect the coupon for signs of substrate interaction: fiber whitening (CFRP), surface crazing (thermoplastics), fiber mat exposure (FRP), Ra change (metal tools). For composites, use a 10\u00d7 loupe or low-power microscope. Measure Ra after every pass for mold tool qualification. If baseline measurements have shifted, stop and analyze before increasing any parameter.<\/p>\n      <p class=\"pm-tip\">For CFRP specifically: lightly wiping the surface with a clean white cloth after blasting and before inspection will remove loose dust and make any fiber damage far more visible under raking light examination.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-process-step\">\n    <div class=\"pm-process-left\">\n      <div class=\"pm-process-dot\">5<\/div>\n      <div class=\"pm-process-line\"><\/div>\n    <\/div>\n    <div class=\"pm-process-body\">\n      <h4>Confirm Coating Removal Adequacy<\/h4>\n      <p>Simultaneously with substrate condition inspection, confirm that coating removal at the current parameters is adequate. If coating is not fully removed after 3 passes at the starting parameters, incrementally increase pressure (5 PSI steps) or move to a coarser mesh size (one step) and repeat from step 3. If coating removal is adequate but substrate shows damage signs, parameters must be reduced \u2014 this defines the upper bound of the process window.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-process-step\">\n    <div class=\"pm-process-left\">\n      <div class=\"pm-process-dot\">6<\/div>\n      <div class=\"pm-process-line\"><\/div>\n    <\/div>\n    <div class=\"pm-process-body\">\n      <h4>Define and Document the Qualified Process Window<\/h4>\n      <p>The qualified process window is defined by the parameters that achieve adequate coating removal with no measurable substrate damage \u2014 the overlap zone between these two requirements. Document the qualified parameters in a formal process specification, including nozzle type and bore size, pressure (measured at nozzle inlet, not compressor output), mesh size, standoff, angle, and travel speed. This document is your production control reference and, for aerospace work, the basis for your NADCAP or customer-specific process approval submission.<\/p>\n    <\/div>\n  <\/div>\n\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 8 \u2014 STORAGE & HANDLING\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=\"ac-storage\">Storage, Handling &amp; Moisture Control<\/h2>\n\n<p>PMMA&#8217;s moisture absorption characteristic (~0.3% per 24 hours at 50% RH) is the most significant handling difference between Type V acrylic and the thermosetting plastic blast media types. Moisture-absorbed acrylic media breaks down faster during blasting, shortens reuse cycles, and can introduce flow inconsistencies in the media delivery system. Proper storage is essential to capture the full economic value of the media.<\/p>\n\n<div class=\"pm-storage-grid\">\n  <div class=\"pm-storage-card\">\n    <div class=\"pm-storage-head do\">\u2705 DO \u2014 Storage<\/div>\n    <div class=\"pm-storage-body\">Store in original sealed bags until use. After opening, transfer to sealed airtight containers. Include silica gel desiccant packets (replace monthly). Store at 60\u201375\u00b0F (15\u201324\u00b0C) and below 50% RH. Keep off concrete floors (condensation risk).<\/div>\n  <\/div>\n  <div class=\"pm-storage-card\">\n    <div class=\"pm-storage-head dont\">\u274c DON&#8217;T \u2014 Storage<\/div>\n    <div class=\"pm-storage-body\">Do not store in open bags or bins exposed to ambient humidity. Do not store near heat sources (furnaces, compressors) that cause daily temperature cycling and condensation. Do not store outdoors or in unheated\/uncooled storage areas with wide humidity swings.<\/div>\n  <\/div>\n  <div class=\"pm-storage-card\">\n    <div class=\"pm-storage-head do\">\u2705 DO \u2014 Pre-Use<\/div>\n    <div class=\"pm-storage-body\">If moisture exposure is suspected, condition the media by running one &#8220;dry&#8221; blast cycle through a heated blast cabinet (warm air only, no substrate) to drive off surface moisture before loading production parts. This restores flow characteristics and baseline breakdown behavior.<\/div>\n  <\/div>\n  <div class=\"pm-storage-card\">\n    <div class=\"pm-storage-head dont\">\u274c DON&#8217;T \u2014 Handling<\/div>\n    <div class=\"pm-storage-body\">Do not clean blast equipment with ketone (MEK, acetone), ester, or chlorinated solvents while acrylic media is in the reclaim circuit \u2014 PMMA is attacked by these solvents and will show accelerated breakdown. Use isopropyl alcohol or water-based cleaners for equipment cleaning.<\/div>\n  <\/div>\n  <div class=\"pm-storage-card\">\n    <div class=\"pm-storage-head do\">\u2705 DO \u2014 In Circuit<\/div>\n    <div class=\"pm-storage-body\">In the blast cabinet reclaim circuit, maintain media temperature below 140\u00b0F (60\u00b0C). Excessive frictional heating in high-velocity nozzles can soften PMMA particles and cause them to agglomerate rather than fracture cleanly, degrading both strip rate and reclaim separation efficiency.<\/div>\n  <\/div>\n  <div class=\"pm-storage-card\">\n    <div class=\"pm-storage-head dont\">\u274c DON&#8217;T \u2014 In Circuit<\/div>\n    <div class=\"pm-storage-body\">Do not mix acrylic media with other media types in the same hopper. Do not run acrylic media in high-temperature blast environments (hot substrate, high ambient temperature) above the heat deflection limit of 185\u00b0F (85\u00b0C).<\/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 9 \u2014 REUSE CYCLES\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=\"ac-reuse\">Maximizing Reuse Cycles<\/h2>\n\n<p>Type V acrylic typically delivers 2\u20134 reuse cycles \u2014 fewer than urea (3\u20136) or melamine (4\u20138). This is inherent to its thermoplastic nature: PMMA fractures differently from thermosetting resins, producing a higher proportion of non-functional fines per impact event. However, careful process management can push acrylic reuse cycles toward the upper end of the 2\u20134 range:<\/p>\n\n<ul>\n  <li><strong>Minimize blast pressure.<\/strong> Every 5 PSI increase in nozzle pressure measurably reduces reuse cycles for acrylic media. Operating at the minimum effective pressure \u2014 rather than the maximum allowable \u2014 is the single most effective lever for extending media life.<\/li>\n  <li><strong>Calibrate air wash velocity precisely for each mesh size.<\/strong> The air wash separator must be set to carry away fines (sub-effective particles) without discarding intact particles that still have productive life. Miscalibration in either direction wastes good media.<\/li>\n  <li><strong>Prevent moisture exposure between cycles.<\/strong> Moisture-softened PMMA particles fracture at lower energies and produce more fines per cycle. Keep the media charge dry between blast sessions by sealing the hopper or returning unused media to sealed containers.<\/li>\n  <li><strong>Replace the media charge proactively.<\/strong> A media charge that has degraded to 50% of its initial strip rate should be replaced entirely rather than supplemented with fresh media. Mixing degraded and fresh media produces unpredictable blend behavior that is difficult to manage within a qualified process window.<\/li>\n<\/ul>\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 EARLY WARNING SIGNS\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=\"ac-warning\">Early Warning Signs of Over-Blasting<\/h2>\n\n<p>Because Type V acrylic is used on substrates where damage is difficult or impossible to repair, recognizing the early warning signs of over-blasting is critical. These are the observable indicators, organized by substrate type, that should trigger an immediate stop and parameter review:<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Substrate<\/th>\n        <th>Early Warning Sign<\/th>\n        <th>What It Indicates<\/th>\n        <th>Immediate Action<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>CFRP \/ Carbon Fiber<\/td>\n        <td>Surface fiber whitening or frosting under raking light<\/td>\n        <td>Surface fiber bundle disruption beginning \u2014 pre-damage state<\/td>\n        <td>Stop blasting. Reduce pressure 10 PSI or increase mesh fineness by one step. Re-qualify.<\/td>\n      <\/tr>\n      <tr>\n        <td>CFRP \/ Carbon Fiber<\/td>\n        <td>Fuzzy or feathered surface texture when viewed obliquely<\/td>\n        <td>Individual fiber severance \u2014 damage has occurred<\/td>\n        <td>Stop immediately. Engineer evaluation required before proceeding. Document and report.<\/td>\n      <\/tr>\n      <tr>\n        <td>Thermoplastic<\/td>\n        <td>Surface gloss reduction or matte appearance in blasted zone<\/td>\n        <td>Surface layer yielding beginning (early stress whitening)<\/td>\n        <td>Reduce pressure 5\u201310 PSI, increase standoff 2\u20133 inches. Re-evaluate on fresh coupon.<\/td>\n      <\/tr>\n      <tr>\n        <td>Thermoplastic<\/td>\n        <td>Visible white haze or clouding under surface<\/td>\n        <td>Stress whitening \u2014 matrix yielding with void formation<\/td>\n        <td>Stop. Part may be cosmetically unacceptable. Reduce all parameters significantly.<\/td>\n      <\/tr>\n      <tr>\n        <td>Fiberglass (FRP)<\/td>\n        <td>Gelcoat texture becoming granular or woven pattern beginning to show<\/td>\n        <td>Gelcoat layer being removed unevenly, approaching fiber mat<\/td>\n        <td>Reduce pressure, increase standoff, slow nozzle travel. Single-pass maximum.<\/td>\n      <\/tr>\n      <tr>\n        <td>Mold Tool Surface<\/td>\n        <td>Surface haze visible in polished cavity areas<\/td>\n        <td>Acrylic particles altering polished Ra \u2014 measurable roughening<\/td>\n        <td>Stop. Measure Ra immediately. Reduce mesh to next finer size and reduce pressure.<\/td>\n      <\/tr>\n      <tr>\n        <td>Radome \/ Antenna Cover<\/td>\n        <td>Any visible surface texture change from baseline<\/td>\n        <td>Dielectric property alteration risk \u2014 requires electrical test before further blasting<\/td>\n        <td>Stop. Perform transmission loss measurement per maintenance manual before proceeding.<\/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 LIMITS OF ACRYLIC\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=\"ac-limits\">The Limits of Acrylic: When Even Type V Isn&#8217;t Enough<\/h2>\n\n<p>Type V acrylic is the gentlest practical blast abrasive available, but it is not universally applicable to all sensitive surfaces. There are situations where even acrylic at the lowest practical parameters will cause unacceptable substrate interaction, and where alternative cleaning methods must be considered:<\/p>\n\n<h3>Bare Optical Glass and Precision Optical Coatings<\/h3>\n<p>Optical elements \u2014 lenses, mirrors, windows \u2014 and their anti-reflection or high-reflectance coatings are typically produced with Ra values below 1 nm (0.001 \u00b5m). Even Type V acrylic at Mesh 80 and 15 PSI will alter such surfaces beyond recovery. Optical cleaning must use chemical methods (appropriate solvent wipes, ultrasonic cleaning in pH-neutral solutions) rather than any mechanical abrasive.<\/p>\n\n<h3>Thin-Film Coatings on Electronic Substrates<\/h3>\n<p>Sputtered or evaporated thin-film coatings (metallic or dielectric layers in the nanometer thickness range) on semiconductor or optical substrates cannot survive any blast process. Even the turbulent airflow around an acrylic blast stream would disturb nanometer-thickness coatings. Wet chemical cleaning is the only viable approach.<\/p>\n\n<h3>Parts with Exposed Bond Wires or Fine Conductor Lines<\/h3>\n<p>Wire-bonded integrated circuits or substrates with conductor line widths below 50 \u00b5m cannot be exposed to acrylic blast media without risk of wire displacement or conductor damage from even indirect particle impact. Precision cleaning with CO\u2082 pellets (dry ice blasting at extremely low pressure) or laser ablation are alternatives for these applications.<\/p>\n\n<h3>Very Thick or Highly Adhered Coatings on Sensitive Substrates<\/h3>\n<p>If a CFRP structure carries six or more layers of well-adhered mil-spec coating, Type V acrylic at safe substrate parameters may not have enough cutting authority to remove the coating in a practical number of passes. In this scenario, a two-stage process is sometimes used: a controlled first stage with fine-mesh Type II urea at minimum parameters removes most coating layers, followed by a Type V acrylic finish pass to clean the final residual layer from the bare substrate without risk. This approach requires individual qualification for each coating system and substrate combination.<\/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 12 \u2014 VS WALNUT SHELL\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=\"ac-vs\">Acrylic vs Walnut Shell on Sensitive Substrates<\/h2>\n\n<p>Walnut shell is the organic abrasive most frequently compared to Type V acrylic for sensitive surface applications. Both have similar Mohs hardness (~3.0\u20133.5), and both are used where substrate protection is the primary concern. Here is how they compare across the dimensions that matter for sensitive substrate operations:<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Attribute<\/th>\n        <th>Type V Acrylic (PMMA)<\/th>\n        <th>Walnut Shell<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Mohs-H\u00e4rte<\/td>\n        <td>~3.0<\/td>\n        <td>~3.5<\/td>\n      <\/tr>\n      <tr>\n        <td>Echte Dichte<\/td>\n        <td>1.18 g\/cm\u00b3 (lighter)<\/td>\n        <td>~1.28 g\/cm\u00b3<\/td>\n      <\/tr>\n      <tr>\n        <td>Impact Behavior<\/td>\n        <td>Viscoelastic deformation \u2192 fracture<\/td>\n        <td>Brittle fracture (harder impact pulse)<\/td>\n      <\/tr>\n      <tr>\n        <td>CFRP Compatibility<\/td>\n        <td><span class=\"pm-badge pm-badge-high\">Better \u2014 lower peak stress<\/span><\/td>\n        <td><span class=\"pm-badge pm-badge-med\">Fair \u2014 higher hardness, more risk<\/span><\/td>\n      <\/tr>\n      <tr>\n        <td>MIL-SPEC Availability<\/td>\n        <td><span class=\"pm-badge pm-badge-high\">Yes \u2014 MIL-P-85891A Type V<\/span><\/td>\n        <td><span class=\"pm-badge pm-badge-low\">No military specification<\/span><\/td>\n      <\/tr>\n      <tr>\n        <td>Moisture Sensitivity<\/td>\n        <td>Moderate (PMMA hygroscopic)<\/td>\n        <td>High (organic; swells significantly with moisture)<\/td>\n      <\/tr>\n      <tr>\n        <td>Biological \/ Mold Risk<\/td>\n        <td>None (synthetic)<\/td>\n        <td>Present if stored in humid conditions<\/td>\n      <\/tr>\n      <tr>\n        <td>Particle Shape Consistency<\/td>\n        <td><span class=\"pm-badge pm-badge-high\">High (engineered)<\/span><\/td>\n        <td><span class=\"pm-badge pm-badge-med\">Variable (natural material)<\/span><\/td>\n      <\/tr>\n      <tr>\n        <td>Reuse Cycles<\/td>\n        <td>2\u20134<\/td>\n        <td>2\u20135 (variable; degrades faster when wet)<\/td>\n      <\/tr>\n      <tr>\n        <td>Process Window (CFRP)<\/td>\n        <td><span class=\"pm-badge pm-badge-high\">Wider \u2014 lower damage risk<\/span><\/td>\n        <td><span class=\"pm-badge pm-badge-med\">Narrower<\/span><\/td>\n      <\/tr>\n      <tr>\n        <td>Environmental Disposal<\/td>\n        <td>Non-hazardous solid (if non-contaminated)<\/td>\n        <td>Non-hazardous (organic); compostable if uncontaminated<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p>For applications requiring MIL-SPEC traceability \u2014 all defense aerospace work \u2014 Type V acrylic is the required choice because walnut shell has no military specification. For non-defense sensitive surface applications (marine FRP, commercial composite structures), walnut shell can be a cost-effective alternative, but its variable particle shape, biological contamination risk during storage, and higher effective hardness make it a less reliable choice than engineered acrylic media for critical applications. Full comparison: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/plastic-media-vs-walnut-shell-which-is-better\/\">Plastic Media vs Walnut Shell: Which Is Better?<\/a><\/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 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=\"ac-faq\">H\u00e4ufig gestellte Fragen<\/h2>\n\n<div class=\"pm-faq\" 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\">Can Type V acrylic media be used in a standard blast cabinet designed for mineral abrasives?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Technically yes, but with significant limitations. Standard mineral abrasive blast cabinets are not equipped with the air wash separator and fine-screen reclaim systems needed to effectively reclaim and reuse acrylic media. Without proper reclaim, every advantage of acrylic media \u2014 reusability and reduced per-part cost \u2014 is eliminated, and you are effectively paying a premium per-pound price for a single-use abrasive. Additionally, standard cabinet nozzle systems may not offer the fine pressure control needed for acrylic blast operations on sensitive substrates. Dedicated plastic media blast systems with calibrated reclaim are strongly recommended for any production acrylic blast process.<\/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\">How do I know if my CFRP part has been damaged by over-blasting with acrylic media?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Early-stage blast damage on CFRP can be difficult to detect with the naked eye \u2014 which is exactly what makes process control so critical. Visual inspection under raking light at low angles to the surface is the most accessible first check: damaged fiber bundles appear as a frosted, matte, or slightly fuzzy texture compared to the clean, slightly glossy appearance of undamaged bare CFRP. More sensitive detection methods include: low-power optical microscopy (10\u201340\u00d7) for surface fiber condition; ultrasonic C-scan for inter-ply delamination detection; and peel-ply surface preparation tests (if applicable) to reveal matrix integrity at the surface layer. For flight-critical structure, any suspected over-blasting event should trigger an engineering evaluation before the part is returned to service.<\/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 Type V acrylic media the same product as what is sold as &#8220;PMMA blast media&#8221; by industrial suppliers?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">PMMA blast media and MIL-P-85891A Type V acrylic media are based on the same resin chemistry, but not all commercial PMMA blast media meets the military specification. MIL-P-85891A Type V imposes specific requirements on particle size distribution, moisture content, bulk density, pH, and free monomer content, and requires a Certificate of Conformance documenting lot-specific test results. Generic &#8220;PMMA blast media&#8221; from a commodity supplier may or may not meet these requirements. For aerospace and defense applications, always specify MIL-P-85891A Type V and request CoC documentation. For non-defense sensitive surface applications, confirm with the supplier what testing their product undergoes and whether it would meet the MIL-SPEC parameters even if not formally certified.<\/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\">After blasting a CFRP surface with Type V acrylic, what surface preparation is needed before adhesive bonding?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">The surface preparation sequence after acrylic blast on CFRP prior to structural adhesive bonding typically includes: (1) compressed air blow-off to remove loose acrylic dust and coating debris; (2) solvent wipe with isopropyl alcohol on a lint-free cloth to remove any acrylic residue or contamination (avoid ketones or chlorinated solvents that attack PMMA); (3) visual and tactile inspection under raking light to confirm coating removal completeness and absence of fiber damage; (4) application of adhesive primer within the time window specified by the bondline process specification, typically within 4\u20138 hours to prevent re-contamination. For aerospace structural bonds, a water break test (water sheeting uniformly across the blasted surface without beading) is often required to confirm surface cleanliness before primer application. Consult the applicable composite repair manual for the specific bonded assembly you are working on.<\/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 Type V acrylic media be used on painted surfaces over aluminum without risk of substrate damage?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Yes \u2014 acrylic media is fully compatible with aluminum substrates and will not damage them at any practical blast pressure. If your substrate is aluminum (not composite), and your concern is gentle coating removal rather than CFRP protection, Type V acrylic is a valid but usually unnecessary choice. Type II urea (Type II, Mesh 30\u201340) achieves the same substrate-safe coating removal on aluminum at meaningfully higher strip rates and lower per-part media cost. Reserve Type V acrylic for applications where the substrate genuinely requires it \u2014 composite, thermoplastic, or polished metal surfaces \u2014 and use Type II urea as the default for standard aluminum structures.<\/p>\n    <\/div>\n  <\/div>\n\n<\/div>\n\n<hr class=\"pm-section-divider\">","protected":false},"excerpt":{"rendered":"<p>Acrylic (Type V) Plastic Media for Sensitive Surfaces There is  [&#8230;]<\/p>","protected":false},"author":1,"featured_media":12327,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,177,138],"tags":[],"class_list":["post-12307","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-material","category-resource"],"_links":{"self":[{"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/posts\/12307","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/comments?post=12307"}],"version-history":[{"count":4,"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/posts\/12307\/revisions"}],"predecessor-version":[{"id":12398,"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/posts\/12307\/revisions\/12398"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/media\/12327"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/media?parent=12307"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/categories?post=12307"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/de\/wp-json\/wp\/v2\/tags?post=12307"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}