{"id":13458,"date":"2026-06-24T06:36:11","date_gmt":"2026-06-24T06:36:11","guid":{"rendered":"https:\/\/hlh-js.com\/?p=13458"},"modified":"2026-06-24T06:36:11","modified_gmt":"2026-06-24T06:36:11","slug":"plastic-abrasive-media-urea-vs-melamine-grit-for-delicate-substrates","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/es\/resource\/blog\/plastic-abrasive-media-urea-vs-melamine-grit-for-delicate-substrates\/","title":{"rendered":"Plastic Abrasive Media: Urea vs Melamine Grit for Delicate Substrates"},"content":{"rendered":"<style>\n.hlh-p{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Oxygen,Ubuntu,sans-serif;color:#2d3748;line-height:1.78;max-width:900px;margin:0 auto;font-size:1rem}\n.hlh-p *{box-sizing:border-box}\n.hlh-p p{margin:0 0 1.3rem}\n.hlh-p h1{font-size:2.25rem;font-weight:800;color:#1a3456;margin:0 0 1.25rem;line-height:1.25}\n.hlh-p h2{font-size:1.65rem;font-weight:700;color:#1a3456;margin:2.75rem 0 1rem;padding-bottom:.55rem;border-bottom:3px solid #d86e18}\n.hlh-p h3{font-size:1.15rem;font-weight:600;color:#1a3456;margin:1.6rem 0 .5rem}\n.hlh-p ul,.hlh-p ol{margin:0 0 1.25rem;padding-left:1.5rem}\n.hlh-p li{margin:.35rem 0}\n.hlh-p strong{font-weight:600;color:#1a3456}\n.hlh-p a{color:#d86e18;text-decoration:none}\n.hlh-p a:hover{text-decoration:underline;color:#b55c14}\n.hlh-toc{background:#f7f9fc;border:1px solid #dde4ef;border-left:4px solid #d86e18;border-radius:8px;padding:1.4rem 1.75rem;margin:2rem 0}\n.hlh-toc-ttl{font-size:.76rem;text-transform:uppercase;letter-spacing:.09em;color:#7a8aa0;font-weight:700;margin:0 0 .75rem}\n.hlh-toc ol{margin:0;padding-left:1.2rem}\n.hlh-toc li{margin:.3rem 0;font-size:.9rem}\n.hlh-toc a{color:#1a3456;font-weight:500;text-decoration:none}\n.hlh-toc a:hover{color:#d86e18}\n.hlh-callout{background:#eef5ff;border-left:4px solid #3b82f6;border-radius:6px;padding:1rem 1.3rem;margin:1.5rem 0}\n.hlh-callout p{margin:0;font-size:.9rem;color:#1e3a5f;line-height:1.65}\n.hlh-twrap{overflow-x:auto;margin:1.5rem 0;border-radius:8px;border:1px solid #e5eaf2}\n.hlh-tbl{width:100%;border-collapse:collapse;font-size:.84rem;min-width:480px}\n.hlh-tbl thead th{background:#1a3456;color:#fff;padding:.75rem 1rem;text-align:left;font-weight:600;white-space:nowrap}\n.hlh-tbl tbody td{padding:.6rem 1rem;border-bottom:1px solid #eef1f7;color:#2d3748;vertical-align:top}\n.hlh-tbl tbody tr:last-child td{border-bottom:none}\n.hlh-tbl tbody tr:nth-child(even) td{background:#f8fafd}\n.hlh-tbl tbody tr:hover td{background:#edf4ff}\n.hlh-good{color:#15803d;font-weight:600}\n.hlh-fair{color:#b45309;font-weight:600}\n.hlh-flist{margin:1rem 0}\n.hlh-fitem{border:1px solid #e5eaf2;border-radius:8px;margin:.6rem 0;padding:1rem 1.25rem}\n.hlh-fq{font-weight:600;color:#1a3456;font-size:.93rem;margin:0 0 .5rem}\n.hlh-fa{font-size:.88rem;color:#5a6a80;margin:0;line-height:1.65}\n.hlh-cta{background:linear-gradient(130deg,#1a3456 0%,#2a508a 100%);border-radius:12px;padding:2.5rem 2rem;text-align:center;margin:3rem 0 1rem;color:#fff}\n.hlh-cta h2{color:#fff!important;border:none!important;margin:0 0 .75rem;font-size:1.45rem;padding:0!important}\n.hlh-cta p{color:rgba(255,255,255,.88);margin:0 0 1.5rem;font-size:1rem}\n.hlh-ctabtn{display:inline-block;background:#d86e18;color:#fff!important;padding:.8rem 2.25rem;border-radius:50px;font-weight:700;text-decoration:none!important;font-size:.95rem}\n.hlh-ctabtn:hover{background:#b55c14!important}\n@media(max-width:640px){.hlh-cta{padding:1.75rem 1.25rem}}\n<\/style>\n\n<div class=\"hlh-p\">\n<h1>Plastic Abrasive Media: Urea vs Melamine Grit for Delicate Substrates<\/h1>\n\n<p>When the substrate cannot tolerate the impact energy, hardness, or material removal rate of conventional mineral or metallic abrasives \u2014 and yet a controlled surface preparation or coating removal is required \u2014 plastic abrasive media is the engineered solution. Manufactured from thermosetting plastics (primarily urea-formaldehyde and melamine-formaldehyde resins), plastic grit offers hardness low enough to leave aluminum, fiberglass, and composite substrates dimensionally unaffected, while still delivering sufficient cutting action to strip multiple layers of paint, epoxy coating, or primer in a single blast pass. This combination of controlled aggressiveness and substrate safety is what makes plastic abrasive media the standard specification in aerospace MRO, automotive refinishing, and marine coating maintenance.<\/p>\n\n<p>This guide covers the two main plastic grit types, their performance differences, and the applications where each is specified. For the full context of soft and delicate-surface abrasive options within the broader product range, see the <a href=\"https:\/\/hlh-js.com\/resource\/blog\/abrasive-media-supplies\/\" target=\"_blank\" rel=\"noopener\">Abrasive Media Supplies Buyer&#8217;s Guide<\/a>.<\/p>\n\n<div class=\"hlh-toc\">\n  <div class=\"hlh-toc-ttl\">Table of Contents<\/div>\n  <ol>\n    <li><a href=\"#plast-what\">What Is Plastic Abrasive Media?<\/a><\/li>\n    <li><a href=\"#plast-types\">Urea (Type II) vs Melamine (Type V)<\/a><\/li>\n    <li><a href=\"#plast-grit\">Grit Sizes and Operating Pressures<\/a><\/li>\n    <li><a href=\"#plast-apps\">Core Applications<\/a><\/li>\n    <li><a href=\"#plast-walnut\">Plastic Media vs Walnut Shell and Other Organic Abrasives<\/a><\/li>\n    <li><a href=\"#plast-faq\">Preguntas frecuentes<\/a><\/li>\n  <\/ol>\n<\/div>\n\n<h2 id=\"plast-what\">What Is Plastic Abrasive Media?<\/h2>\n<p>Plastic abrasive media \u2014 also called plastic grit \u2014 is manufactured by crushing or granulating thermoset polymer materials into angular particles that are then screened to a defined grit size distribution. Unlike thermoplastic materials (which would deform under impact rather than fracturing), thermosetting plastics form a rigid, cross-linked molecular structure on curing that gives them sufficient hardness and brittleness to function as abrasives \u2014 yet their hardness of just 3\u20134 on the Mohs scale is far below that of any metallic or mineral abrasive, which is the fundamental source of their utility for delicate substrate applications.<\/p>\n\n<p>The military specification MIL-P-85891 defines two commercially dominant types of plastic abrasive grit for stripping aircraft coatings: <strong>Type II<\/strong> (urea-formaldehyde, typically white or light-colored) and <strong>Type V<\/strong> (melamine-formaldehyde, typically white to translucent). Both are manufactured in angular particle form and function by a controlled scoring and fracture mechanism on the coating surface \u2014 the grit particles are hard enough to cut into the coating layer, but not hard enough to deform or remove the substrate material beneath it, provided the correct grit size, blast pressure, and stand-off distance are used within the specification limits.<\/p>\n\n<h2 id=\"plast-types\">Urea (Type II) vs Melamine (Type V)<\/h2>\n\n<div class=\"hlh-twrap\">\n  <table class=\"hlh-tbl\">\n    <thead>\n      <tr><th>Property<\/th><th>Urea Type II<\/th><th>Melamine Type V<\/th><\/tr>\n    <\/thead>\n    <tbody>\n      <tr><td>Base Material<\/td><td>Urea-formaldehyde resin<\/td><td>Melamine-formaldehyde resin<\/td><\/tr>\n      <tr><td>Dureza Mohs<\/td><td>3\u20133.5<\/td><td>3.5\u20134<\/td><\/tr>\n      <tr><td>Peso espec\u00edfico<\/td><td>~1.5 g\/cm\u00b3<\/td><td>~1.5 g\/cm\u00b3<\/td><\/tr>\n      <tr><td>Reuse Cycles<\/td><td>20\u201335<\/td><td class=\"hlh-good\">30\u201345<\/td><\/tr>\n      <tr><td>Friability<\/td><td class=\"hlh-good\">Higher (more brittle)<\/td><td>Lower (tougher)<\/td><\/tr>\n      <tr><td>Cutting Aggressiveness<\/td><td>Moderado<\/td><td class=\"hlh-good\">Slightly higher<\/td><\/tr>\n      <tr><td>Substrate Risk<\/td><td class=\"hlh-good\">Lower<\/td><td>Slightly higher<\/td><\/tr>\n      <tr><td>Unit Cost<\/td><td class=\"hlh-good\">Lower<\/td><td>Higher<\/td><\/tr>\n      <tr><td>Best Application<\/td><td>Delicate aluminum skins, composites, thin-gauge panels<\/td><td>Thicker aluminum structures, steel with sensitive alloy coating<\/td><\/tr>\n      <tr><td>MIL-P-85891 Type<\/td><td>Type II<\/td><td>Type V<\/td><\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p><strong>Urea Type II<\/strong> is the softer of the two, with a higher degree of friability that limits the energy transferred to the substrate on impact \u2014 each particle is more likely to fracture on contact, absorbing and dissipating the kinetic energy rather than transmitting it to the substrate. This makes urea the preferred choice for the most delicate applications: thin-gauge aluminum fuselage skins, fiberglass radome structures, and honeycomb composite panels where any substrate distortion would require expensive re-work or component replacement.<\/p>\n\n<p><strong>Melamine Type V<\/strong> is slightly harder and tougher, giving it a marginally higher strip rate on thick or tenacious coating systems (multiple layers of epoxy primer and topcoat on a structural aluminum panel, for example) and a better reuse cycle count per kilogram of media. It is the standard choice for heavy coating removal on large aluminum structural components \u2014 wing spars, fuselage frames, engine nacelles \u2014 and for steel marine components where the substrate is robust enough to tolerate the slightly higher impact intensity.<\/p>\n\n<h2 id=\"plast-grit\">Grit Sizes and Operating Pressures<\/h2>\n\n<div class=\"hlh-twrap\">\n  <table class=\"hlh-tbl\">\n    <thead>\n      <tr><th>Grit Size<\/th><th>Mean Particle Size<\/th><th>Typical Blast Pressure<\/th><th>Aplicaci\u00f3n<\/th><\/tr>\n    <\/thead>\n    <tbody>\n      <tr><td>14 grit<\/td><td>~1,400 \u00b5m<\/td><td>40\u201360 psi<\/td><td>Heavy topcoat removal, thick epoxy systems<\/td><\/tr>\n      <tr><td>20 grit<\/td><td>~850 \u00b5m<\/td><td>40\u201365 psi<\/td><td>Standard stripping, most aerospace MRO applications<\/td><\/tr>\n      <tr><td>30 grit<\/td><td>~600 \u00b5m<\/td><td>35\u201360 psi<\/td><td>General coating removal, automotive refinishing<\/td><\/tr>\n      <tr><td>40 grit<\/td><td>~425 \u00b5m<\/td><td>30\u201355 psi<\/td><td>Controlled strip of thin coatings, delicate substrates<\/td><\/tr>\n      <tr><td>60 grit<\/td><td>~250 \u00b5m<\/td><td>25\u201345 psi<\/td><td>Very delicate substrates, thin-gauge aluminum<\/td><\/tr>\n      <tr><td>80 grit<\/td><td>~180 \u00b5m<\/td><td>20\u201340 psi<\/td><td>Surface prep and light cleaning, fiberglass<\/td><\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p>Blast pressure is a critical control parameter for plastic media. Unlike harder abrasives, where higher pressure generally improves cut rate without risk of substrate damage, plastic grit has a relatively narrow optimum pressure window. Too low, and the particles lack sufficient kinetic energy to cut the coating effectively; too high, and the increased impact energy can cause substrate deformation \u2014 particularly on thin aluminum skins (below 1.5 mm gauge). Most aerospace MRO process specifications define the allowable pressure range for each substrate thickness and specify that any variation requires re-qualification of the process.<\/p>\n\n<h2 id=\"plast-apps\">Core Applications<\/h2>\n\n<h3>Aerospace MRO: Aircraft Coating Stripping<\/h3>\n<p>Periodic aircraft repainting requires removal of the existing topcoat, primer, and often conversion coating from the aluminum or composite airframe structure. Chemical stripping agents are effective but environmentally regulated and require long dwell times and extensive protective measures. Plastic abrasive media blasting \u2014 typically melamine Type V in 20\u201330 grit range at 40\u201360 psi, applied through a suction blast nozzle in a booth equipped with appropriate dust collection \u2014 removes aircraft coatings at rates of several square meters per hour without any risk of aluminum skin thinning, provided the process is operated within the qualified parameters. This process is specified by most major airframe OEMs and is standard procedure in commercial aircraft MRO facilities worldwide.<\/p>\n\n<h3>Automotive Refinishing and Body Restoration<\/h3>\n<p>Automotive body shops and restoration specialists use plastic grit in 30\u201340 grit range for stripping paint from vehicle body panels without warping thin-gauge steel or aluminum sheet. The low impact energy of plastic media \u2014 compared to glass beads, sodium bicarbonate, or any mineral abrasive \u2014 allows it to be applied to complex curved body panel geometries without the differential stress concentration at panel edges and transitions that causes distortion with harder media. For automotive-specific media selection across the full range of applications, see: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/abrasive-media-for-automotive-restoration-paint-stripping\/\" target=\"_blank\" rel=\"noopener\">Abrasive Media for Automotive Restoration &amp; Paint Stripping<\/a>.<\/p>\n\n<h3>Marine Coating Maintenance<\/h3>\n<p>Ship and boat superstructure components \u2014 particularly aluminum topsides, wheelhouses, and deck equipment on naval and commercial vessels \u2014 require periodic re-coating that first necessitates removal of the existing coating system without compromising the thin-gauge aluminum structure. Melamine grit in 20\u201330 grit range is the preferred media for this application on aluminum marine structures, delivering controlled coating removal at the production rates needed for major vessel maintenance periods.<\/p>\n\n<h3>Composite and Fiberglass Structures<\/h3>\n<p>Carbon fiber reinforced polymer (CFRP) and glass fiber composite structures \u2014 increasingly used in aerospace, wind energy, automotive, and marine applications \u2014 are particularly sensitive to surface preparation. Any abrasive that is harder than the resin matrix of the composite (most mineral and metallic abrasives) risks exposing fiber ends at the surface, which can wick moisture and degrade bond strength. Urea Type II plastic grit is the safest option for composite surface preparation and intercoat adhesion blasting, providing controlled surface roughening of the resin matrix without cutting individual reinforcement fibers.<\/p>\n\n<h2 id=\"plast-walnut\">Plastic Media vs Walnut Shell and Other Organic Abrasives<\/h2>\n\n<div class=\"hlh-twrap\">\n  <table class=\"hlh-tbl\">\n    <thead>\n      <tr><th>Factor<\/th><th>Plastic Grit (Urea \/ Melamine)<\/th><th>Walnut Shell Grit<\/th><th>Corn Cob Grit<\/th><\/tr>\n    <\/thead>\n    <tbody>\n      <tr><td>Hardness (Mohs)<\/td><td>3\u20134<\/td><td>3.5\u20134<\/td><td>2\u20133<\/td><\/tr>\n      <tr><td>Cutting Aggressiveness<\/td><td class=\"hlh-good\">Moderate (controlled)<\/td><td>Moderado<\/td><td>Very low<\/td><\/tr>\n      <tr><td>Reuse Cycles<\/td><td class=\"hlh-good\">20\u201345<\/td><td class=\"hlh-fair\">5\u201315<\/td><td class=\"hlh-fair\">3\u201310<\/td><\/tr>\n      <tr><td>Moisture Sensitivity<\/td><td class=\"hlh-good\">Bajo<\/td><td class=\"hlh-fair\">High (swells)<\/td><td class=\"hlh-fair\">High (swells)<\/td><\/tr>\n      <tr><td>Biodegradability<\/td><td>No (synthetic polymer)<\/td><td class=\"hlh-good\">Yes<\/td><td class=\"hlh-good\">Yes<\/td><\/tr>\n      <tr><td>Food Contact Safe<\/td><td>Generally no<\/td><td class=\"hlh-good\">Yes (processed correctly)<\/td><td class=\"hlh-good\">Yes<\/td><\/tr>\n      <tr><td>Best For<\/td><td>Aerospace MRO, automotive, marine composite<\/td><td>Turbine blades, antique metalwork, soft alloys<\/td><td>Gentle cleaning, cosmetics equipment<\/td><\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p>The primary advantage of plastic grit over walnut shell in most industrial applications is its higher reuse cycle count and lower moisture sensitivity. Walnut shell, being a natural organic material, absorbs moisture readily \u2014 leading to particle swelling, clumping, and loss of flowability in humid environments. Plastic grit, being a synthetic thermoset polymer, is essentially non-hygroscopic and maintains its particle geometry and flow characteristics across a wide humidity range, which is important for consistent process performance in blast booths that may not be climate-controlled.<\/p>\n\n<h2 id=\"plast-faq\">Preguntas frecuentes<\/h2>\n<div class=\"hlh-flist\">\n\n  <div class=\"hlh-fitem\">\n    <div class=\"hlh-fq\">Can plastic abrasive media be used on carbon steel?<\/div>\n    <p class=\"hlh-fa\">Plastic grit can clean and texture carbon steel surfaces, but its low Mohs hardness (3\u20134) limits its ability to remove mill scale, heavy rust, or tightly adherent coating from hard steel substrates. On mill-scale-free, lightly rusted, or previously blasted steel, plastic grit can achieve a clean surface condition. However, it cannot produce the Sa 2.5 or Sa 3 cleanliness with deep anchor profiles required for heavy protective coatings on structural steel \u2014 for that, angular metallic or mineral abrasives are required. Plastic grit is best used on steel only when the substrate is sensitive enough that harder abrasives cannot be used, or for the final light cleaning step before cosmetic finishing.<\/p>\n  <\/div>\n\n  <div class=\"hlh-fitem\">\n    <div class=\"hlh-fq\">How do I dispose of spent plastic abrasive media?<\/div>\n    <p class=\"hlh-fa\">Spent plastic abrasive media is classified as solid waste (not hazardous waste in most jurisdictions) and can typically be disposed of in industrial solid waste landfill in most regions. However, the spent media contains the stripped coating material \u2014 which may include lead-based paint, chromate primer, or other regulated coating components depending on the age and history of the coated structure. In that case, the spent media-plus-coating waste may be classified as hazardous waste, and disposal must comply with applicable environmental regulations for the waste composition. Always characterize spent media for regulated coating components before determining the appropriate disposal route.<\/p>\n  <\/div>\n\n  <div class=\"hlh-fitem\">\n    <div class=\"hlh-fq\">What equipment is needed for plastic abrasive blasting?<\/div>\n    <p class=\"hlh-fa\">Plastic abrasive blasting uses standard pressure blast or suction blast equipment, but several equipment characteristics optimize performance with plastic media. Because plastic grit is significantly lighter than mineral or metallic abrasives (specific gravity ~1.5 vs 3.9\u20137.8 for other media), it requires lower blast pressures and larger nozzle orifices than heavier abrasives to maintain adequate velocity and coverage rate. Most plastic media blast systems operate at 25\u201365 psi with nozzle sizes #5\u2013#7. Efficient dust collection is essential because plastic grit generates fine polymer dust that requires adequate filtration. A well-calibrated separator or classifier is also needed to remove fines and broken particles and maintain the working mix at the correct grit size distribution.<\/p>\n  <\/div>\n\n<\/div>\n\n<div class=\"hlh-cta\">\n  <h2>Source Plastic Abrasive Grit from Henglihong<\/h2>\n  <p>Urea Type II and Melamine Type V per MIL-P-85891, in 14\u201380 grit range. Factory-direct pricing with export documentation for aerospace, automotive, and marine buyers.<\/p>\n  <a href=\"https:\/\/hlh-js.com\/contact\/\" class=\"hlh-ctabtn\" target=\"_blank\" rel=\"noopener\">Get a Free Quote<\/a>\n<\/div>\n\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Plastic Abrasive Media: Urea vs Melamine Grit for Delicate Substrates  [&#8230;]<\/p>","protected":false},"author":1,"featured_media":13460,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,177,138],"tags":[],"class_list":["post-13458","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-material","category-resource"],"_links":{"self":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/13458","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/comments?post=13458"}],"version-history":[{"count":2,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/13458\/revisions"}],"predecessor-version":[{"id":13461,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/13458\/revisions\/13461"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/media\/13460"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/media?parent=13458"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/categories?post=13458"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/tags?post=13458"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}