{"id":12348,"date":"2026-03-02T06:13:36","date_gmt":"2026-03-02T06:13:36","guid":{"rendered":"https:\/\/hlh-js.com\/?p=12348"},"modified":"2026-03-02T07:22:59","modified_gmt":"2026-03-02T07:22:59","slug":"plastic-media-vs-glass-bead-pros-and-cons","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/ja\/resource\/blog\/plastic-media-vs-glass-bead-pros-and-cons\/","title":{"rendered":"Plastic Media vs Glass Bead: Pros and Cons"},"content":{"rendered":"<!-- ============================================================\n     CLUSTER ARTICLE #15 \u2014 WordPress Post Content\n     Title: Plastic Media vs Glass Bead: Pros and Cons\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 \u5bf9\u6bd4\u4e3b\u9898\uff1a\u5de5\u4e1a\u84dd \u00d7 \u73bb\u7483\u9752 \u2500\u2500 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.pm-vs-header{grid-template-columns:1fr}\n  .pm-vs-divider{padding:8px}\n  .pm-h2h-row{grid-template-columns:1fr}\n  .pm-h2h-cell.prop{background:#1e293b;color:#e2e8f0;border-right:none}\n  .pm-mech-grid,.pm-finish-grid,.pm-health-grid,.pm-scorecard{grid-template-columns:1fr}\n}\n@media(max-width:480px){\n  .pm-app-grid{grid-template-columns:1fr}\n  .pm-bar-pair{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 INTRO \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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>Plastic Media vs Glass Bead: Pros and Cons<\/h1>\n<p>Plastic blast media and glass bead are both used on aluminum, steel, and other metal substrates without the substrate-destruction risk of mineral abrasives. They appear in the same equipment catalogs, are specified by similar mesh size systems, and both produce surfaces that are ready for coating or further processing. For operators encountering both options for the first time, the question of which to choose \u2014 and why \u2014 is genuinely non-obvious.<\/p>\n\n<p>The answer lies in a fundamental mechanical difference between the two media that shapes everything downstream: plastic media cuts and fractures coatings through angular impact, removing material from the substrate surface. Glass bead peens and compresses the surface through spherical impact, producing a compressive stress layer without removing base material. These are not variations of the same process \u2014 they are two different surface engineering operations that share the same equipment and the same loose category label of &#8220;abrasive blasting.&#8221;<\/p>\n\n<p>Understanding that difference \u2014 its causes, its consequences for surface finish, its implications for coating adhesion, fatigue life, and regulatory acceptance \u2014 is what this guide delivers. By the end, you will know exactly when plastic media is the right choice, exactly when glass bead is the right choice, and exactly when operators mistakenly substitute one for the other at cost to their results.<\/p>\n\n<p>For the complete plastic media type guide, 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<!-- 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=\"#gb-overview\">The Fundamental Difference: Cutting vs. Peening<\/a><\/li>\n    <li><a href=\"#gb-properties\">Physical Properties Head-to-Head<\/a><\/li>\n    <li><a href=\"#gb-performance\">Performance Comparison Across Key Dimensions<\/a><\/li>\n    <li><a href=\"#gb-surface\">Surface Finish: What Each Media Actually Does to the Substrate<\/a><\/li>\n    <li><a href=\"#gb-coating\">Coating Adhesion: Where Each Media Has the Advantage<\/a><\/li>\n    <li><a href=\"#gb-fatigue\">Fatigue Life: The Glass Bead Advantage<\/a><\/li>\n    <li><a href=\"#gb-substrate\">Substrate Compatibility Guide<\/a><\/li>\n    <li><a href=\"#gb-health\">Health and Safety: The Silica Question<\/a><\/li>\n    <li><a href=\"#gb-reuse\">Reusability and Media Life<\/a><\/li>\n    <li><a href=\"#gb-cost\">Cost Comparison<\/a><\/li>\n    <li><a href=\"#gb-applications\">Application-by-Application Decision Guide<\/a><\/li>\n    <li><a href=\"#gb-scorecard\">Overall Scorecard<\/a><\/li>\n    <li><a href=\"#gb-faq\">\u3088\u304f\u3042\u308b\u8cea\u554f<\/a><\/li>\n    <li><a href=\"#gb-related\">Related Guides<\/a><\/li>\n  <\/ol>\n<\/nav>\n\n\n<!-- VS HEADER -->\n<div class=\"pm-vs-header\">\n  <div class=\"pm-vs-plastic\">\n    <div class=\"pm-vs-eyebrow\">Engineered Polymer Abrasive<\/div>\n    <div class=\"pm-vs-name\">Plastic Blast Media<\/div>\n    <div class=\"pm-vs-sub\">Angular thermoset particle \u00b7 Cuts and fractures coatings \u00b7 Urea, melamine, or acrylic<\/div>\n  <\/div>\n  <div class=\"pm-vs-divider\">VS<\/div>\n  <div class=\"pm-vs-glass\">\n    <div class=\"pm-vs-eyebrow\">Manufactured Glass Spheres<\/div>\n    <div class=\"pm-vs-name\">Glass Bead<\/div>\n    <div class=\"pm-vs-sub\">Spherical borosilicate glass \u00b7 Peens and compresses surface \u00b7 ANSI B74.18 \/ MIL-G-9954A<\/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 S1 \u2014 FUNDAMENTAL DIFFERENCE \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-overview\">The Fundamental Difference: Cutting vs. Peening<\/h2>\n\n<p>The most important fact about this comparison is that plastic blast media and glass bead are not competing solutions to the same problem \u2014 they are solutions to two different problems that are sometimes confused with each other. Getting this straight is the prerequisite for everything else.<\/p>\n\n<div class=\"pm-mech-grid\">\n  <div class=\"pm-mech-card\">\n    <div class=\"pm-mech-head cut\">\ud83d\udd37 Plastic Media: Angular Impact \u2014 Cutting Action<\/div>\n    <div class=\"pm-mech-body\">\n      Plastic blast media particles have irregular, angular geometry. When an angular particle impacts a coated surface at blast velocity, the sharp edges concentrate stress at the coating-substrate interface. Above a threshold energy level, this concentrated stress fractures the coating adhesion bond and lifts material from the surface \u2014 classic abrasive cutting action. The base metal surface after plastic media blasting shows a directionally-random, matte-textured profile with defined peaks and valleys \u2014 the anchor profile that mechanical coating adhesion relies on.\n      <ul>\n        <li><strong>Primary action:<\/strong> Material removal (coating and sometimes a thin layer of substrate)<\/li>\n        <li><strong>Net surface change:<\/strong> Rougher than pre-blast; defined Ra and Rz<\/li>\n        <li><strong>Stress state introduced:<\/strong> Neutral to slight tensile at surface<\/li>\n        <li><strong>Best when:<\/strong> You need to remove something (coating, oxide, contamination)<\/li>\n      <\/ul>\n    <\/div>\n  <\/div>\n  <div class=\"pm-mech-card\">\n    <div class=\"pm-mech-head peen\">\u26aa Glass Bead: Spherical Impact \u2014 Peening Action<\/div>\n    <div class=\"pm-mech-body\">\n      Glass bead particles are manufactured as near-perfect spheres. When a sphere impacts a metal surface at blast velocity, it cannot concentrate stress at a point or edge \u2014 all impact energy is distributed over the contact area of the sphere. This distributed impact deforms the surface layer plastically without cutting or removing metal. The result is a burnished, compressed surface layer in a uniform compressive stress state. Glass-beaded surfaces appear uniformly matte to semi-bright and feel smooth to the touch.\n      <ul>\n        <li><strong>Primary action:<\/strong> Surface compressive deformation (peening), not removal<\/li>\n        <li><strong>Net surface change:<\/strong> Smoother or unchanged Ra; compressive stress layer introduced<\/li>\n        <li><strong>Stress state introduced:<\/strong> Compressive \u2014 extends fatigue life of the component<\/li>\n        <li><strong>Best when:<\/strong> You need to change surface properties (stress state, appearance, cleanliness) without removing material<\/li>\n      <\/ul>\n    <\/div>\n  <\/div>\n<\/div>\n\n<div class=\"pm-callout\">\n  <strong>The common substitution mistake:<\/strong> The most frequent error in choosing between these two media is using glass bead to strip coatings from aluminum or steel and expecting plastic-media-like results. Glass bead at normal operating pressures cannot reliably remove well-adhered paint from metal \u2014 the spherical impact geometry lacks the stress concentration needed to fracture coating adhesion bonds. Operators who try this end up with partially stripped, polished-looking surfaces that look clean but retain a thin coating film that causes premature paint failure. Conversely, using plastic media where glass bead is specified (fatigue-sensitive parts, decorative finishing) introduces the wrong surface stress state and the wrong Ra for the application.\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 S2 \u2014 PROPERTIES H2H \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-properties\">Physical Properties Head-to-Head<\/h2>\n\n<div class=\"pm-h2h\">\n  <div class=\"pm-h2h-row hdr\">\n    <div class=\"pm-h2h-cell\">Property<\/div>\n    <div class=\"pm-h2h-cell\">Plastic Blast Media<\/div>\n    <div class=\"pm-h2h-cell\">Glass Bead<\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Mohs hardness<\/div>\n    <div class=\"pm-h2h-cell pl\">2.5\u20134.0 (Type II Urea ~3.5; Type V Acrylic ~3.0)<\/div>\n    <div class=\"pm-h2h-cell gb\">5.5\u20136.5 (borosilicate glass) \u2014 significantly harder than plastic media and softer metals like aluminum<\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">\u7c92\u5b50\u5f62\u72b6<\/div>\n    <div class=\"pm-h2h-cell pl\">Angular irregular \u2014 sharp edges produce cutting\/fracturing action on coatings <span class=\"pm-tag-p\">\u2713 for stripping<\/span><\/div>\n    <div class=\"pm-h2h-cell gb\">Spherical \u2014 distributes impact energy; produces peening not cutting <span class=\"pm-tag-g\">\u2713 for peening\/finishing<\/span><\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Specific gravity<\/div>\n    <div class=\"pm-h2h-cell pl\">1.2\u20131.5 g\/cm\u00b3 \u2014 lighter; lower kinetic energy per particle at same velocity<\/div>\n    <div class=\"pm-h2h-cell gb\">2.45\u20132.55 g\/cm\u00b3 \u2014 significantly denser; more kinetic energy per particle at same velocity<\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Silica \/ free silica content<\/div>\n    <div class=\"pm-h2h-cell pl\">Zero \u2014 inorganic silica-free polymer <span class=\"pm-tag-p\">\u2713 no silicosis risk<\/span><\/div>\n    <div class=\"pm-h2h-cell gb\">Glass bead is amorphous silica \u2014 not crystalline free silica; OSHA does not classify glass bead dust as a silicosis hazard under current rules, but respiratory protection is still required for dust exposure<\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Fracture behavior<\/div>\n    <div class=\"pm-h2h-cell pl\">Fractures into smaller angular particles \u2014 usable fragments recaptured by reclaim system<\/div>\n    <div class=\"pm-h2h-cell gb\">Fractures into sharp glass shards \u2014 fractured glass is a laceration hazard and creates respirable fines faster than intact bead; reclaim efficiency decreases with each cycle<\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Surface profile produced (Ra)<\/div>\n    <div class=\"pm-h2h-cell pl\">32\u2013250 \u00b5in Ra depending on mesh and pressure \u2014 angular profile with defined peaks\/valleys optimal for mechanical coating adhesion <span class=\"pm-tag-p\">\u2713 for coating prep<\/span><\/div>\n    <div class=\"pm-h2h-cell gb\">8\u201363 \u00b5in Ra \u2014 smooth, compressive, dimpled profile; lower Ra than plastic at same mesh; optimal for decorative finishing and fatigue-life applications <span class=\"pm-tag-g\">\u2713 for finishing<\/span><\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Compressive stress introduced<\/div>\n    <div class=\"pm-h2h-cell pl\">Minimal to none \u2014 angular impact at moderate pressures introduces minimal beneficial compressive stress<\/div>\n    <div class=\"pm-h2h-cell gb\">Significant \u2014 spherical peening action introduces measurable compressive residual stress layer; documented fatigue life improvement of 20\u2013200% depending on material and geometry <span class=\"pm-tag-g\">\u2713 fatigue applications<\/span><\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Coating removal capability<\/div>\n    <div class=\"pm-h2h-cell pl\">Excellent \u2014 purpose-designed for selective coating removal from substrates <span class=\"pm-tag-p\">\u2713 wins decisively<\/span><\/div>\n    <div class=\"pm-h2h-cell gb\">Poor for well-adhered coatings \u2014 spherical impact cannot reliably fracture coating adhesion bonds; may polish loose or poorly adhered coatings rather than remove them<\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Substrate damage risk on aluminum<\/div>\n    <div class=\"pm-h2h-cell pl\">Low at correct pressure \u2014 Mohs 3\u20134 close to aluminum Mohs 2.5\u20133.5; wide safe working window<\/div>\n    <div class=\"pm-h2h-cell gb\">Moderate \u2014 Mohs 5.5\u20136.5 harder than aluminum; at high pressures or with worn\/fractured bead, glass bead can score and erosion-damage aluminum surfaces; safe at correctly qualified low pressures<\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Iron contamination risk<\/div>\n    <div class=\"pm-h2h-cell pl\">Zero \u2014 non-metallic polymer <span class=\"pm-tag-tie\">\u2248 tie<\/span><\/div>\n    <div class=\"pm-h2h-cell gb\">Zero \u2014 non-metallic glass <span class=\"pm-tag-tie\">\u2248 tie<\/span><\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Specification standards<\/div>\n    <div class=\"pm-h2h-cell pl\">MIL-P-85891A (aerospace blast media) <span class=\"pm-tag-p\">\u2713 coating removal spec<\/span><\/div>\n    <div class=\"pm-h2h-cell gb\">MIL-G-9954A \/ ANSI B74.18 \/ SAE J1173 (glass bead shot peening) <span class=\"pm-tag-g\">\u2713 peening \/ finishing spec<\/span><\/div>\n  <\/div>\n  <div class=\"pm-h2h-row\">\n    <div class=\"pm-h2h-cell prop\">Typical cost per pound<\/div>\n    <div class=\"pm-h2h-cell pl\">$1.20\u2013$1.80\/lb (Type II urea); $1.80\u2013$2.80\/lb (Type V acrylic)<\/div>\n    <div class=\"pm-h2h-cell gb\">$0.50\u2013$1.10\/lb \u2014 lower purchase price; but lower reclaim cycles offset this<\/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 S3 \u2014 PERFORMANCE BARS \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-performance\">Performance Comparison Across Key Dimensions<\/h2>\n\n<div class=\"pm-bar-row\">\n  <div class=\"pm-bar-label\">Coating Removal Effectiveness (well-adhered paint on metal)<\/div>\n  <div class=\"pm-bar-pair\">\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name pl\">\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill pl\" style=\"width:90%\">90% \u2014 Excellent<\/div><\/div><\/div>\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name gb\">Glass Bead<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill gb\" style=\"width:22%\">22% \u2014 Poor<\/div><\/div><\/div>\n  <\/div>\n<\/div>\n<div class=\"pm-bar-row\">\n  <div class=\"pm-bar-label\">Compressive Stress \/ Fatigue Life Improvement<\/div>\n  <div class=\"pm-bar-pair\">\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name pl\">\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill pl\" style=\"width:18%\">18% \u2014 Minimal<\/div><\/div><\/div>\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name gb\">Glass Bead<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill gb\" style=\"width:88%\">88% \u2014 Excellent<\/div><\/div><\/div>\n  <\/div>\n<\/div>\n<div class=\"pm-bar-row\">\n  <div class=\"pm-bar-label\">Surface Profile for Mechanical Coating Adhesion (anchor pattern quality)<\/div>\n  <div class=\"pm-bar-pair\">\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name pl\">\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill pl\" style=\"width:85%\">85% \u2014 Excellent anchor profile<\/div><\/div><\/div>\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name gb\">Glass Bead<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill gb\" style=\"width:40%\">40% \u2014 Low Ra, minimal anchor<\/div><\/div><\/div>\n  <\/div>\n<\/div>\n<div class=\"pm-bar-row\">\n  <div class=\"pm-bar-label\">Decorative Satin \/ Matte Finish Quality on Bare Metal<\/div>\n  <div class=\"pm-bar-pair\">\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name pl\">\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill pl\" style=\"width:50%\">50% \u2014 Functional but coarser<\/div><\/div><\/div>\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name gb\">Glass Bead<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill gb\" style=\"width:92%\">92% \u2014 Excellent satin finish<\/div><\/div><\/div>\n  <\/div>\n<\/div>\n<div class=\"pm-bar-row\">\n  <div class=\"pm-bar-label\">Substrate Safety on Thin Aluminum (damage avoidance at working pressures)<\/div>\n  <div class=\"pm-bar-pair\">\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name pl\">\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill pl\" style=\"width:88%\">88% \u2014 Excellent (Mohs close to Al)<\/div><\/div><\/div>\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name gb\">Glass Bead<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill gb\" style=\"width:68%\">68% \u2014 Good (harder than Al; requires care)<\/div><\/div><\/div>\n  <\/div>\n<\/div>\n<div class=\"pm-bar-row\">\n  <div class=\"pm-bar-label\">Reusability (cycles achievable with reclaim system)<\/div>\n  <div class=\"pm-bar-pair\">\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name pl\">\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill pl\" style=\"width:78%\">4\u20138 cycles<\/div><\/div><\/div>\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name gb\">Glass Bead<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill gb\" style=\"width:48%\">2\u20134 cycles (shard hazard limits reclaim)<\/div><\/div><\/div>\n  <\/div>\n<\/div>\n<div class=\"pm-bar-row\">\n  <div class=\"pm-bar-label\">Parameter Consistency Across Lots and Storage Conditions<\/div>\n  <div class=\"pm-bar-pair\">\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name pl\">\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill pl\" style=\"width:90%\">90% \u2014 Excellent<\/div><\/div><\/div>\n    <div class=\"pm-bar-wrap\"><div class=\"pm-bar-name gb\">Glass Bead<\/div><div class=\"pm-bar-track\"><div class=\"pm-bar-fill gb\" style=\"width:82%\">82% \u2014 Very Good (moisture-stable)<\/div><\/div><\/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 S4 \u2014 SURFACE FINISH \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-surface\">Surface Finish: What Each Media Actually Does to the Substrate<\/h2>\n\n<p>The surface condition produced by plastic media and glass bead are so different that they serve distinct downstream applications. Understanding the difference in quantitative terms \u2014 Ra values, surface texture character, and stress state \u2014 is essential for specifying the right media for a given application.<\/p>\n\n<div class=\"pm-finish-grid\">\n  <div class=\"pm-finish-card\">\n    <div class=\"pm-finish-head pl\">\ud83d\udd37 Plastic Media \u2014 Surface Finish Profile<\/div>\n    <div class=\"pm-finish-body\">\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Typical Ra range<\/span><span class=\"pm-finish-val\">32\u2013250 \u00b5in (0.8\u20136.4 \u00b5m)<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Surface texture character<\/span><span class=\"pm-finish-val\">Angular, directional-random, matte<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Peak-to-valley depth (Rz)<\/span><span class=\"pm-finish-val\">High relative to Ra \u2014 sharp peaks<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Residual stress state<\/span><span class=\"pm-finish-val\">Neutral to slight tensile<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Visual appearance<\/span><span class=\"pm-finish-val\">Uniform matte \u2014 no sheen<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Coating adhesion suitability<\/span><span class=\"pm-finish-val\">Excellent \u2014 anchor profile<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Decorative suitability (bare metal)<\/span><span class=\"pm-finish-val\">Limited \u2014 too rough for satin finish<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-finish-card\">\n    <div class=\"pm-finish-head gb\">\u26aa Glass Bead \u2014 Surface Finish Profile<\/div>\n    <div class=\"pm-finish-body\">\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Typical Ra range<\/span><span class=\"pm-finish-val\">8\u201363 \u00b5in (0.2\u20131.6 \u00b5m)<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Surface texture character<\/span><span class=\"pm-finish-val\">Smooth, dimpled, uniform satin<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Peak-to-valley depth (Rz)<\/span><span class=\"pm-finish-val\">Low relative to Ra \u2014 rounded dimples<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Residual stress state<\/span><span class=\"pm-finish-val\">Compressive \u2014 measurable and beneficial<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Visual appearance<\/span><span class=\"pm-finish-val\">Uniform satin sheen \u2014 premium appearance<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Coating adhesion suitability<\/span><span class=\"pm-finish-val\">Moderate \u2014 low Ra reduces mechanical bond<\/span><\/div>\n      <div class=\"pm-finish-row\"><span class=\"pm-finish-label\">Decorative suitability (bare metal)<\/span><span class=\"pm-finish-val\">Excellent \u2014 standard for aerospace\/medical hardware<\/span><\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<p>The practical implication of these different Ra values: if your application specifies a surface profile of 50\u2013100 \u00b5in Ra for mechanical coating adhesion (a common range for epoxy primer over blasted steel), plastic media can hit this target directly with the appropriate mesh selection. Glass bead cannot approach this Ra at standard operating conditions \u2014 it will produce 20\u201340 \u00b5in at most, leaving the surface underprofile for thick coating systems. Conversely, if your application specifies a decorative satin finish on bare aluminum hardware at 16\u201332 \u00b5in Ra (common for aerospace and medical device components), glass bead hits this target precisely while plastic media would leave the surface too rough and directionally textured for the appearance specification.<\/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 S5 \u2014 COATING ADHESION \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-coating\">Coating Adhesion: Where Each Media Has the Advantage<\/h2>\n\n<p>The relationship between surface preparation media and coating adhesion is one of the most practically important dimensions of this comparison \u2014 and one where operators most often make costly mistakes by using the wrong media for the coating system that follows.<\/p>\n\n<h3>Plastic Media and Mechanical Coating Adhesion<\/h3>\n<p>Coatings adhere to metal surfaces through a combination of mechanical interlocking (paint resin flowing into surface profile peaks and valleys, then curing around them) and chemical bonding (primer chemistry reacting with the metal oxide surface layer). Plastic media blasting optimizes the mechanical adhesion component by producing the angular surface profile \u2014 defined peaks and valleys \u2014 that maximizes mechanical interlocking contact area. The Ra produced by plastic media (32\u2013250 \u00b5in) is well-matched to the profile requirements of epoxy primers, polyurethane topcoats, powder coatings, and other structural coating systems that specify a &#8220;blast-cleaned&#8221; surface with defined minimum anchor profile.<\/p>\n\n<h3>Glass Bead and Coating Adhesion<\/h3>\n<p>Glass bead&#8217;s smooth, dimpled surface profile produces lower mechanical adhesion than plastic media for coatings that rely on anchor profile. This is not a limitation in applications where glass bead is correctly specified \u2014 decorative satin finishes on bare hardware, fatigue-treated components that will not be coated, or components where a thin clear lacquer or conversion coating (chromate, anodize) will be applied over the beaded surface. It becomes a problem when glass bead is used as a substitute for plastic media in coating preparation applications. A glass-beaded surface with 20 \u00b5in Ra under an epoxy primer specified for 50\u2013100 \u00b5in anchor profile will show premature adhesion failure \u2014 not because the primer is bad or the application was wrong, but because the surface was not prepared to the mechanical specification the primer requires.<\/p>\n\n<div class=\"pm-callout pm-callout-warn\">\n  <strong>The critical warning for coating over glass-beaded surfaces:<\/strong> If a part has been glass-bead finished for decorative or fatigue purposes and then requires a structural coating, do not apply the coating directly over the beaded surface without re-blasting with plastic media or another angular abrasive to build the required anchor profile. The glass bead has produced a mechanically complete surface for its intended purpose \u2014 but that surface is incompatible with the adhesion requirements of structural coating systems. Always verify the surface profile specification before specifying a finishing media.\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 S6 \u2014 FATIGUE LIFE \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-fatigue\">Fatigue Life: The Glass Bead Advantage<\/h2>\n\n<p>Shot peening with glass bead \u2014 properly controlled with Almen strip intensity verification \u2014 is one of the most widely used and well-documented methods of improving the fatigue life of metal components subjected to cyclic stress. The mechanism is straightforward: the compressive residual stress layer introduced by the spherical impact of glass bead acts to counteract the tensile stress at the surface that drives fatigue crack initiation and propagation. A crack cannot initiate or grow in a region that is under compressive stress because compression closes crack faces rather than opening them.<\/p>\n\n<p>The magnitude of fatigue life improvement from glass bead peening depends on the base material, component geometry, and peening intensity \u2014 but documented improvements range from 20% for modestly stressed steel components to 200% or more for high-strength titanium or aluminum structures with stress concentration features (holes, fillets, transitions). Aerospace landing gear, turbine disks, and spring components are routinely glass-bead peened in production as a defined life-extension step in the manufacturing process.<\/p>\n\n<p>Plastic media blasting does not provide meaningful shot peening effect. The combination of lower density (1.2\u20131.5 g\/cm\u00b3 vs. glass bead&#8217;s 2.45\u20132.55 g\/cm\u00b3), lower hardness, and angular geometry means plastic media impact produces little of the uniform plastic deformation at the surface that generates compressive stress. If fatigue life improvement is the objective of the blasting operation, glass bead is the correct media. Plastic media cannot substitute for it.<\/p>\n\n<div class=\"pm-callout pm-callout-green\">\n  <strong>The two-step process for fatigue-critical coated components:<\/strong> Some components require both coating removal (for inspection access or refinishing) and maintained or restored fatigue life. The correct sequence is: strip the coating with plastic media \u2192 perform NDI (non-destructive inspection) on the bare metal \u2192 glass bead peen to restore compressive stress layer \u2192 apply new coating. Using glass bead for the strip step fails the stripping objective; using plastic media for the peen step fails the fatigue objective. Each step requires its designated media type.\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 S7 \u2014 SUBSTRATE COMPATIBILITY \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-substrate\">Substrate Compatibility Guide<\/h2>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Substrate<\/th>\n        <th>\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/th>\n        <th>Glass Bead<\/th>\n        <th>Recommended Choice<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Aluminum aircraft structure (coating removal)<\/td>\n        <td>\u2705 Excellent \u2014 purpose designed; MIL-P-85891A; zero iron contamination; qualifiable by Almen strip<\/td>\n        <td>\u26a0\ufe0f Will not reliably remove well-adhered coating; may polish loose areas. Mohs 5.5\u20136.5 harder than aluminum \u2014 requires carefully controlled low pressure to avoid surface erosion.<\/td>\n        <td><strong>\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>Aluminum aircraft structure (fatigue treatment, no coating removal)<\/td>\n        <td>\u274c Inadequate peening action \u2014 does not produce meaningful compressive stress layer<\/td>\n        <td>\u2705 Excellent \u2014 standard aerospace process; MIL-G-9954A; Almen intensity documented; compressive stress layer verified<\/td>\n        <td><strong>Glass Bead<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>Stainless steel hardware (decorative satin finish)<\/td>\n        <td>\u26a0\ufe0f Achieves matte finish but too rough for premium satin appearance; directional texture visible<\/td>\n        <td>\u2705 Excellent \u2014 produces uniform satin finish; standard for medical device, food equipment, and architectural stainless; no surface directionality<\/td>\n        <td><strong>Glass Bead<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>Steel automotive panels (paint stripping)<\/td>\n        <td>\u2705 Excellent \u2014 designed for this application; produces correct anchor profile for primer<\/td>\n        <td>\u274c Not suitable for removing well-adhered automotive paint; will not achieve complete strip; incorrect surface profile for primer adhesion<\/td>\n        <td><strong>\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>Titanium aerospace components (fatigue treatment)<\/td>\n        <td>\u274c Insufficient peening intensity \u2014 does not generate required compressive stress in titanium<\/td>\n        <td>\u2705 Standard treatment for titanium springs, fasteners, structural components; documented improvement in high-cycle fatigue performance<\/td>\n        <td><strong>Glass Bead<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>CFRP \/ composite (coating removal)<\/td>\n        <td>\u2705 Type V acrylic only \u2014 the sole approved media for composite depainting in most aerospace specs<\/td>\n        <td>\u274c Glass bead Mohs 5.5\u20136.5 significantly harder than carbon fiber epoxy matrix \u2014 high risk of fiber damage; not approved for composite depainting<\/td>\n        <td><strong>Plastic Media (Type V only)<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>Injection mold tool steel (cleaning)<\/td>\n        <td>\u2705 Type V acrylic preferred \u2014 zero residue, controlled Ra, approved for cavity cleaning<\/td>\n        <td>\u26a0\ufe0f Glass bead Mohs 5.5\u20136.5 harder than P20 (HRC 28\u201334) \u2014 at even moderate pressures can alter Ra of polished cavity surfaces; use only with extreme care at very low pressure and fine mesh<\/td>\n        <td><strong>\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>Spring steel \/ coil springs (fatigue treatment)<\/td>\n        <td>\u274c Will not produce fatigue-life improvement<\/td>\n        <td>\u2705 Standard treatment for high-stress spring components; improves fatigue life 50\u2013150% in well-controlled shot peen processes<\/td>\n        <td><strong>Glass Bead<\/strong><\/td>\n      <\/tr>\n      <tr>\n        <td>Brass \/ copper hardware (decorative cleaning)<\/td>\n        <td>\u26a0\ufe0f Can remove oxidation but leaves rough texture; may alter color uniformity of brass<\/td>\n        <td>\u2705 Excellent for brass, copper, and bronze \u2014 gentle cleaning action with uniform satin finish; widely used in trophy, musical instrument, and decorative hardware finishing<\/td>\n        <td><strong>Glass Bead<\/strong><\/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 S8 \u2014 HEALTH \/ SILICA \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-health\">Health and Safety: The Silica Question<\/h2>\n\n<p>One of the most frequently misunderstood aspects of the plastic media vs. glass bead comparison is the health and safety distinction \u2014 specifically around silica exposure. The concern arises from glass bead&#8217;s glass composition, which is primarily silica (SiO\u2082). The critical distinction, however, is between crystalline silica and amorphous silica \u2014 and it matters enormously for regulatory classification and occupational health risk.<\/p>\n\n<div class=\"pm-health-grid\">\n  <div class=\"pm-health-card safe\">\n    <div class=\"pm-health-head\">\ud83d\udd35 Plastic Media \u2014 Silica Hazard Profile<\/div>\n    <div class=\"pm-health-body\">\n      <ul>\n        <li>Zero silica content \u2014 thermoset polymer (urea, melamine, or acrylic resin)<\/li>\n        <li>No silicosis risk from the media itself \u2014 completely silica-free<\/li>\n        <li>Respirable dust from plastic media fracture is classified as nuisance dust under OSHA standards<\/li>\n        <li>Coating residue in blast stream carries its own hazard profile (chromate, lead) \u2014 separate from media hazard<\/li>\n        <li>Respiratory protection still required: P100 half-face for cabinet; supplied-air for blast room<\/li>\n        <li>No special handling requirements for the media material itself beyond standard PPE<\/li>\n      <\/ul>\n    <\/div>\n  <\/div>\n  <div class=\"pm-health-card risk\">\n    <div class=\"pm-health-head\">\u26aa Glass Bead \u2014 Silica Hazard Profile<\/div>\n    <div class=\"pm-health-body\">\n      <ul>\n        <li>Composed of amorphous (non-crystalline) silica \u2014 borosilicate glass is an amorphous solid<\/li>\n        <li>OSHA does NOT classify glass bead dust as a crystalline silica hazard under 29 CFR 1910.1053 \u2014 the silicosis hazard rule applies to crystalline (quartz\/cristobalite) silica, not amorphous glass<\/li>\n        <li>However: fractured glass bead produces sharp glass shards at respirable particle size \u2014 laceration risk at cut points in skin and respiratory epithelium<\/li>\n        <li>NIOSH recommends treating fine glass bead dust as a nuisance dust but notes that some epidemiological studies suggest long-term heavy exposure to amorphous glass fibers warrants caution<\/li>\n        <li>Respiratory protection required: P100 half-face minimum for cabinet; supplied-air for blast room<\/li>\n        <li>Eye protection mandatory \u2014 fractured glass bead produces sharp shards at high velocity; standard safety glasses are the minimum; blast hood with polycarbonate face shield for all active blasting<\/li>\n        <li>Fractured glass bead in spent media: higher laceration risk during handling than spent plastic media<\/li>\n      <\/ul>\n    <\/div>\n  <\/div>\n<\/div>\n\n<div class=\"pm-callout pm-callout-blue\">\n  <strong>Key takeaway on silica:<\/strong> Glass bead is not subject to OSHA&#8217;s crystalline silica standard (29 CFR 1910.1053) because it is amorphous, not crystalline silica. The silicosis risk associated with silica sand blasting does not apply to glass bead operations under current regulations. However, fractured glass bead produces sharp glass shards that warrant full PPE regardless \u2014 the lacerative hazard is real even if the silicosis regulatory classification does not apply.\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 S9 \u2014 REUSE \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-reuse\">Reusability and Media Life<\/h2>\n\n<p>Both plastic media and glass bead are reusable through reclaim systems, but the reclaim dynamics are meaningfully different \u2014 primarily because of the different ways they fracture during use.<\/p>\n\n<p>Plastic media fractures into smaller angular fragments that maintain their useful cutting geometry through multiple cycles. The reclaim air wash separates fine plastic media fracture products cleanly from usable particles because the density and size differential between the two fractions is relatively consistent. Plastic media achieves 4\u20138 productive cycles in a well-maintained reclaim operation.<\/p>\n\n<p>Glass bead fractures into sharp glass shards \u2014 irregular fragments with very different air resistance than intact spheres. This creates two reclaim challenges. First, fractured glass shards are a laceration hazard during media handling, recycled media screening, and air wash maintenance \u2014 operators working with spent glass bead must use cut-resistant gloves in addition to standard blast PPE. Second, glass shards have inconsistent density and drag coefficients compared to intact spheres, making air wash calibration less precise \u2014 some intact beads are carried over into waste while some shards pass through to the clean media output. The reclaim efficiency for glass bead is lower than for plastic media, typically 2\u20134 productive cycles before the shard content and fine fraction make further reclaim impractical.<\/p>\n\n<p>Additionally, glass bead loses its spherical geometry as it fractures \u2014 once a bead cracks, the resulting fragment no longer produces the smooth peening action of an intact sphere. If the application requires controlled peening intensity (Almen strip verification), spent glass bead with high shard content cannot maintain the required Almen intensity at the same operating parameters as fresh bead, requiring pressure adjustment or media replacement to maintain the process specification.<\/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 S10 \u2014 COST \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-cost\">Cost Comparison<\/h2>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Cost Factor<\/th>\n        <th>\u30d7\u30e9\u30b9\u30c1\u30c3\u30af\u30fb\u30e1\u30c7\u30a3\u30a2<\/th>\n        <th>Glass Bead<\/th>\n        <th>Advantage<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Purchase price per pound<\/td>\n        <td>$1.20\u2013$1.80 (Type II urea)<\/td>\n        <td>$0.50\u2013$1.10<\/td>\n        <td>Glass Bead (lower purchase price)<\/td>\n      <\/tr>\n      <tr>\n        <td>Reuse cycles (reclaim)<\/td>\n        <td>4\u20138\u00d7<\/td>\n        <td>2\u20134\u00d7<\/td>\n        <td>Plastic Media (more cycles)<\/td>\n      <\/tr>\n      <tr>\n        <td>Effective cost per cycle<\/td>\n        <td>$0.18\u2013$0.45\/lb used<\/td>\n        <td>$0.15\u2013$0.55\/lb used<\/td>\n        <td>Roughly comparable at volume<\/td>\n      <\/tr>\n      <tr>\n        <td>Reclaim system complexity<\/td>\n        <td>Standard air wash + screen classifier<\/td>\n        <td>Standard air wash + screen classifier; cut-resistant gloves for media handling<\/td>\n        <td>Slight edge to Plastic Media (simpler handling)<\/td>\n      <\/tr>\n      <tr>\n        <td>Spent media disposal (non-hazardous coating)<\/td>\n        <td>Non-hazardous solid waste<\/td>\n        <td>Non-hazardous solid waste \u2014 sharp glass shard content requires puncture-resistant waste bags<\/td>\n        <td>Slight edge to Plastic Media (safer handling)<\/td>\n      <\/tr>\n      <tr>\n        <td>Equipment wear (nozzle, hose)<\/td>\n        <td>Low \u2014 soft polymer causes minimal equipment wear<\/td>\n        <td>Moderate \u2014 glass (Mohs 5.5\u20136.5) wears nozzles faster than plastic media at the same pressure and flow rate<\/td>\n        <td>Plastic Media (lower equipment wear)<\/td>\n      <\/tr>\n      <tr>\n        <td>Cost of incorrect application<\/td>\n        <td>High if used where glass bead is specified (fatigue not improved; decorative finish too rough)<\/td>\n        <td>High if used where plastic media is specified (coating not removed; wrong anchor profile)<\/td>\n        <td>Tie \u2014 both media types costly when misapplied<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<div class=\"pm-callout pm-callout-orange\">\n  <strong>Nozzle wear is an underappreciated cost difference:<\/strong> Glass bead at Mohs 5.5\u20136.5 wears boron carbide nozzles at roughly 2\u20133\u00d7 the rate of plastic media at Mohs 2.5\u20134.0 at the same operating pressure. In a production blast room running 8 hours per day, this difference translates to nozzle replacement 2\u20133\u00d7 more frequently with glass bead than with plastic media. At $50\u2013$150 per boron carbide nozzle, this is a meaningful ongoing cost that the purchase price comparison does not capture.\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 S11 \u2014 APPLICATIONS \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-applications\">Application-by-Application Decision Guide<\/h2>\n\n<div class=\"pm-app-grid\">\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-plastic\">\u2708\ufe0f Aerospace Coating Removal <span class=\"pm-app-badge\">Use Plastic<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Coating removal from aluminum and composite aircraft structure requires angular cutting action that glass bead cannot provide. MIL-P-85891A is the governing specification; no equivalent glass bead spec covers this application.\n      <div class=\"pm-app-reason\">Glass bead will not strip well-adhered aerospace primers and topcoats.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-glass\">\ud83d\udd04 Shot Peening \/ Fatigue Treatment <span class=\"pm-app-badge\">Use Glass Bead<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Any application where the objective is introduction of compressive residual stress for fatigue life improvement \u2014 springs, landing gear, turbine disks, connecting rods. Governed by MIL-G-9954A and SAE specifications with Almen strip intensity verification.\n      <div class=\"pm-app-reason\">Plastic media cannot generate meaningful compressive stress. No substitute for glass bead here.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-glass\">\u2728 Decorative Satin Finish (Bare Metal) <span class=\"pm-app-badge\">Use Glass Bead<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Medical devices, aerospace hardware, food processing equipment, architectural stainless, trophy and award hardware, watchcase components \u2014 any application requiring a uniform, smooth satin finish on bare metal without coating.\n      <div class=\"pm-app-reason\">Glass bead produces the defining satin texture; plastic media leaves too rough and directional a finish.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-plastic\">\ud83d\ude97 Automotive Paint Stripping <span class=\"pm-app-badge\">Use Plastic<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Full vehicle or panel paint stripping for restoration, repair, or body modification. Plastic media removes all coating layers efficiently and produces the anchor profile required for primer adhesion.\n      <div class=\"pm-app-reason\">Glass bead cannot strip automotive paint. Plastic media is the only choice for this application.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-glass\">\ud83d\udd2c Medical Device \/ Implant Finishing <span class=\"pm-app-badge\">Use Glass Bead<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Orthopedic implants (titanium and cobalt-chrome), surgical instruments, and medical device housings where surface cleanliness, defined Ra, and compressive stress state are specified. Glass bead is the standard finishing media for these applications.\n      <div class=\"pm-app-reason\">Glass bead produces the controlled Ra, compressive stress, and visual finish specified for medical-grade components.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-plastic\">\ud83d\udd27 Mold and Die Cleaning <span class=\"pm-app-badge\">Use Plastic<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Injection mold, die casting die, and compression mold cleaning requires removal of release agent buildup and contamination without altering cavity Ra. Type V acrylic is the standard; glass bead Mohs 5.5\u20136.5 risks cavity surface alteration.\n      <div class=\"pm-app-reason\">Glass bead is too hard for polished mold cavities at practical blast pressures.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-glass\">\ud83d\udd29 Fastener \/ Threaded Hardware Finishing <span class=\"pm-app-badge\">Use Glass Bead<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Glass bead peening of fasteners (bolts, studs, nuts) before installation introduces compressive stress at thread roots \u2014 the highest-stress location in service \u2014 significantly improving fatigue life of threaded connections.\n      <div class=\"pm-app-reason\">Shot peening at thread roots is a defined manufacturing step for high-strength fasteners in aerospace and motorsport applications.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-plastic\">\ud83d\udca1 Electronics Deflashing <span class=\"pm-app-badge\">Use Plastic<\/span><\/div>\n    <div class=\"pm-app-body\">\n      IC package deflashing, connector pin cleaning, and PCB component finishing require ultra-fine media (Mesh 60\u201380) with cutting action to remove flash without substrate damage. Type V acrylic is the standard for this application.\n      <div class=\"pm-app-reason\">Glass bead&#8217;s peening action cannot reliably remove flash from fine electronic features.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-either\">\ud83d\udd28 General Steel Descaling \/ Oxide Removal <span class=\"pm-app-badge\">Either (Context-Dependent)<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Light oxide and heat scale removal from steel where subsequent surface condition requirements are not demanding. Plastic media removes scale more aggressively; glass bead produces a cleaner, more uniform surface with less material removal.\n      <div class=\"pm-app-reason\">Use plastic media if coating adhesion profile matters; glass bead if surface appearance is the priority.<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-app-card\">\n    <div class=\"pm-app-head use-either\">\ud83e\uddea Pre-NDI Surface Preparation <span class=\"pm-app-badge\">Context-Dependent<\/span><\/div>\n    <div class=\"pm-app-body\">\n      Preparing metal surfaces for liquid penetrant or magnetic particle inspection. Plastic media for coating removal prior to inspection; glass bead for cleaning bare metal surfaces that will be inspected after previous coating removal step.\n      <div class=\"pm-app-reason\">Two-step process on coated parts: plastic media to remove coating, then glass bead to clean\/decontaminate for NDI.<\/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 S12 \u2014 SCORECARD \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-scorecard\">Overall Scorecard<\/h2>\n\n<div class=\"pm-scorecard\">\n  <div class=\"pm-score-col\">\n    <div class=\"pm-score-head pl\">\ud83d\udd37 Plastic Media \u2014 Best For<\/div>\n    <div class=\"pm-score-body\">\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Coating removal from any substrate \u2014 the only media type in this comparison capable of reliably stripping well-adhered paint<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Aerospace depainting \u2014 MIL-P-85891A governed; complete regulatory and traceability support<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Composite \/ CFRP depainting \u2014 Type V acrylic is the only approved media<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Mold and die cleaning \u2014 zero residue, hardness-matched to cavity steel<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Electronics deflashing \u2014 fine mesh cutting action removes flash without substrate damage<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Pre-coat surface preparation \u2014 produces the anchor profile (Ra 32\u2013250 \u00b5in) required for mechanical coating adhesion<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Applications requiring zero iron or silica contamination of the substrate<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Operations where equipment longevity matters \u2014 plastic media wears nozzles 2\u20133\u00d7 slower than glass bead<\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-score-col\">\n    <div class=\"pm-score-head gb\">\u26aa Glass Bead \u2014 Best For<\/div>\n    <div class=\"pm-score-body\">\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Shot peening \/ fatigue life improvement \u2014 the only media type in this comparison that produces meaningful compressive residual stress<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Decorative satin finish on bare metal \u2014 produces the uniform, smooth dimpled texture that defines premium hardware finishing<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Medical device and implant finishing \u2014 controlled Ra + compressive stress + biocompatible surface<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Titanium and spring steel fatigue treatment \u2014 aerospace and motorsport production specification<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Fastener shot peening \u2014 thread root compressive stress for high-cycle fatigue applications<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Stainless and brass decorative hardware finishing \u2014 uniform satin without directionality<\/div>\n      <div class=\"pm-score-item\"><span class=\"si\">\u2705<\/span> Pre-NDI surface cleaning of bare metal after coating removal<\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<div class=\"pm-callout pm-callout-gray\">\n  <strong>The verdict:<\/strong> Plastic media and glass bead are not interchangeable \u2014 they solve different problems. Plastic media is the correct choice wherever coating removal, mold cleaning, electronics deflashing, or structural coating preparation is the objective. Glass bead is the correct choice wherever fatigue life improvement, decorative satin finishing, or controlled surface peening is the objective. The majority of operators asking this question are doing coating removal work \u2014 for them, plastic media is unambiguously the answer. Operators doing finishing and fatigue treatment work should use glass bead. For the smaller set of applications where both objectives appear together, the correct answer is almost always a two-step sequence: plastic media first for the coating removal step, glass bead second for the finishing or peening step.\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 FAQ \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\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=\"gb-faq\">\u3088\u304f\u3042\u308b\u8cea\u554f<\/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\">Can glass bead remove paint from aluminum or steel if I use high enough pressure?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Glass bead can remove loose, poorly adhered, or flaking paint at sufficiently high pressure \u2014 the impact energy physically dislodges paint that is already failing. However, it cannot reliably remove well-adhered, intact coating systems from metal substrates at any practical blast pressure. The fundamental constraint is geometric, not energetic: spherical particles distribute impact energy over their entire contact area rather than concentrating it at edges or corners. Well-adhered paint requires concentrated stress at the coating-substrate interface to fracture the adhesion bond \u2014 and a sphere cannot provide that stress concentration regardless of how fast it is traveling. What happens when operators try to strip well-adhered paint with glass bead at high pressure is one of three outcomes: the paint is partially removed in areas where adhesion happened to be marginal, leaving a patchy result that looks stripped but retains a thin residual coating film; the paint is polished to a smooth, intact surface that looks clean but has not been removed; or \u2014 at very high pressure \u2014 the aluminum substrate underneath begins to erode before the well-adhered paint is removed. None of these outcomes is acceptable for coating preparation. For well-adhered coating removal, use angular plastic media.<\/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 glass bead safe to use on aluminum without causing surface damage?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Glass bead can be used safely on aluminum at correctly qualified low pressures, but it requires more careful parameter control than plastic media because glass bead is significantly harder than aluminum. At Mohs 5.5\u20136.5, glass bead is approximately 2\u00d7 the hardness of aluminum (Mohs 2.5\u20133.5) \u2014 meaning the hardness margin that protects aluminum from surface erosion and scoring is much smaller with glass bead than with plastic media (Mohs 2.5\u20134.0, which is comparable to or only slightly harder than aluminum). The practical consequence is that the safe operating pressure window for glass bead on aluminum is narrower than for plastic media, and the consequences of exceeding it are more severe. Properly qualified glass bead peening on aluminum (per MIL-G-9954A with Almen strip intensity documentation) is a well-established aerospace production process that does not damage the aluminum substrate. However, that qualification is specific to the bead size, pressure, and coverage parameters being used. Never assume that glass bead parameters qualified for steel or titanium are safe for aluminum \u2014 aluminum requires separate, specific qualification at lower intensity.<\/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 apply an epoxy primer directly over a glass-bead-finished aluminum surface?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Applying epoxy primer directly over glass-bead-finished aluminum without additional surface preparation is a common cause of premature coating adhesion failure. The problem is the surface profile mismatch: glass bead produces a smooth, dimpled surface at Ra 8\u201332 \u00b5in with rounded peaks, while most epoxy primers specify a minimum anchor profile of 50\u2013100 \u00b5in Ra with angular, sharp-edged peaks to maximize mechanical interlocking. When epoxy primer is applied over a glass-beaded surface that is below the minimum profile specification, the coating may appear well-applied and initially adhered \u2014 but it has insufficient mechanical interlocking contact area, and peel or flake adhesion failures develop within months under service stress, moisture cycling, or thermal cycling. The correct sequence for aluminum that requires both shot peening (fatigue treatment) and coating (corrosion protection) is: glass bead peen at the specified Almen intensity \u2192 apply conversion coating (chromate or non-chromate per specification) \u2192 apply epoxy primer per profile specification \u2192 apply topcoat. The conversion coating provides chemical adhesion that partly compensates for the lower mechanical profile from the glass bead surface. If an angular anchor profile is also required by the coating specification, a very light plastic media blast after glass bead peening (to develop the anchor profile without removing the compressive stress benefit) may be specified in some process documents \u2014 consult your coating system specification before proceeding.<\/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 application requires glass bead or plastic media \u2014 the process engineer who specified it is not available?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Ask two questions about the objective of the blast operation. First: is the goal to remove something from the surface (coating, oxide, contamination) or to change the surface properties without removing material (improve fatigue life, create a decorative finish, clean bare metal)? If removal is the objective, plastic media. If surface property modification is the objective, glass bead. Second: what will happen to the surface after blasting \u2014 will it be coated with a structural primer, or will it be left as bare metal or receive a thin conversion coating\/clear lacquer? If a structural primer with a specified anchor profile will follow, plastic media. If the bare metal surface or thin conversion coating is the final condition, glass bead. If both conditions apply \u2014 coating to be removed AND fatigue life to be improved \u2014 the correct process is two steps: plastic media first for stripping, glass bead second for peening after the coating has been removed and any required NDI has been completed. Do not attempt to accomplish both objectives with a single media type; neither plastic media nor glass bead can do both correctly simultaneously.<\/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\">Does glass bead blasting qualify as shot peening, and do I need Almen strip testing?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Glass bead blasting and glass bead shot peening are related but distinct operations. Glass bead blasting at uncontrolled parameters \u2014 whatever pressure and coverage happens to be convenient \u2014 produces a decorative or cleaning effect but does not qualify as controlled shot peening for fatigue life purposes. Controlled shot peening is a precisely defined process where media size, hardness, velocity (expressed as Almen intensity), coverage, and coverage uniformity are all specified and verified. Almen strip testing \u2014 using calibrated metal coupons that deflect in proportion to the compressive stress introduced \u2014 is the standard method for verifying that the peening intensity meets the process specification. Whether Almen strip testing is required for a specific application depends on what the part will be used for. Decorative satin finishing of stainless hardware? No Almen testing needed \u2014 glass bead is just a surface finishing process in that context. Fatigue treatment of aerospace landing gear, turbine compressor disk, or high-strength fastener? Almen strip documentation is mandatory \u2014 it is the quality record that demonstrates the peening intensity was within the specified range and that the fatigue life benefit has actually been introduced. If you are unsure whether your application requires controlled shot peening with Almen documentation, assume that any safety-critical, fatigue-loaded aerospace or automotive component does require it, and verify with the component&#8217;s design or process specification before blasting.<\/p>\n    <\/div>\n  <\/div>\n\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Plastic Media vs Glass Bead: Pros and Cons Plastic blast  [&#8230;]<\/p>","protected":false},"author":1,"featured_media":12358,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,177,138],"tags":[],"class_list":["post-12348","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-material","category-resource"],"_links":{"self":[{"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/posts\/12348","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/comments?post=12348"}],"version-history":[{"count":4,"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/posts\/12348\/revisions"}],"predecessor-version":[{"id":12409,"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/posts\/12348\/revisions\/12409"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/media\/12358"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/media?parent=12348"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/categories?post=12348"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/ja\/wp-json\/wp\/v2\/tags?post=12348"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}