{"id":12360,"date":"2026-03-02T06:13:49","date_gmt":"2026-03-02T06:13:49","guid":{"rendered":"https:\/\/hlh-js.com\/?p=12360"},"modified":"2026-03-02T06:28:59","modified_gmt":"2026-03-02T06:28:59","slug":"mil-spec-plastic-media-what-mil-p-85891a-means-for-buyers","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/es\/resource\/blog\/mil-spec-plastic-media-what-mil-p-85891a-means-for-buyers\/","title":{"rendered":"Mil-Spec Plastic Media: What MIL-P-85891A Means for Buyers"},"content":{"rendered":"<!-- ============================================================\n     CLUSTER ARTICLE #17 \u2014 WordPress Post Content\n     Title: Mil-Spec Plastic Media: What MIL-P-85891A Means for Buyers\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 \u519b\u89c4\u4e3b\u9898\uff1a\u6df1\u6d77\u519b\u84dd \u00d7 \u94c2\u91d1\u7070 \u2500\u2500 *\/\n.pm-toc{background:#f0f4ff;border:1px solid #c7d2fe;border-left:4px solid #3730a3;padding:24px 28px;margin:0 0 40px;border-radius:4px}\n.pm-toc-title{font-size:13px;font-weight:700;text-transform:uppercase;letter-spacing:.1em;color:#64748b;margin:0 0 14px}\n.pm-toc ol{margin:0;padding-left:20px}\n.pm-toc li{margin:6px 0;font-size:15px}\n.pm-toc li a{color:#3730a3;text-decoration:none;font-weight:500}\n.pm-toc li a:hover{color:#312e81;text-decoration:underline}\n\n.pm-callout{background:#f0f4ff;border:1px solid #c7d2fe;border-left:4px solid #3730a3;padding:16px 20px;margin:24px 0;border-radius:0 4px 4px 0;font-size:15px;line-height:1.65}\n.pm-callout strong{color:#312e81}\n.pm-callout-green{background:#f0fdf4;border-color:#bbf7d0;border-left-color:#16a34a}\n.pm-callout-green strong{color:#15803d}\n.pm-callout-orange{background:#fff7ed;border-color:#fed7aa;border-left-color:#ea580c}\n.pm-callout-orange strong{color:#9a3412}\n.pm-callout-warn{background:#fffbeb;border-color:#fde68a;border-left-color:#d97706}\n.pm-callout-warn strong{color:#92400e}\n.pm-callout-danger{background:#fef2f2;border-color:#fecaca;border-left-color:#dc2626}\n.pm-callout-danger strong{color:#991b1b}\n.pm-callout-gray{background:#f8fafc;border-color:#e2e8f0;border-left-color:#64748b}\n.pm-callout-gray strong{color:#334155}\n\n\/* \u2500\u2500 DOCUMENT ANATOMY CARDS \u2500\u2500 *\/\n.pm-anatomy-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;margin:24px 0}\n.pm-anatomy-card{border:1px solid #e2e8f0;border-radius:8px;overflow:hidden}\n.pm-anatomy-head{padding:11px 16px;font-size:12.5px;font-weight:700;text-transform:uppercase;letter-spacing:.08em;background:#1e1b4b;color:#a5b4fc;display:flex;align-items:center;gap:8px}\n.pm-anatomy-body{padding:13px 16px;background:#f8fafc;font-size:13.5px;color:#374151;line-height:1.65}\n.pm-anatomy-body ul{margin:0;padding-left:16px}\n.pm-anatomy-body ul li{margin:5px 0}\n\n\/* \u2500\u2500 TYPE \u00d7 CLASS MATRIX \u2500\u2500 *\/\n.pm-type-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(215px,1fr));gap:14px;margin:24px 0}\n.pm-type-card{border-radius:8px;overflow:hidden;border:1px solid #e2e8f0}\n.pm-type-head{padding:12px 16px;font-size:13px;font-weight:700;display:flex;align-items:center;justify-content:space-between}\n.pm-type-head.t1{background:#1e3a5f;color:#fff}\n.pm-type-head.t2{background:#1e3a8a;color:#fff}\n.pm-type-head.t3{background:#1e293b;color:#fff}\n.pm-type-head.t4{background:#064e3b;color:#fff}\n.pm-type-head.t5{background:#0c4a6e;color:#fff}\n.pm-type-badge{font-size:10.5px;padding:2px 8px;border-radius:20px;font-weight:600;white-space:nowrap}\n.pm-type-head.t1 .pm-type-badge{background:#bfdbfe;color:#1e3a5f}\n.pm-type-head.t2 .pm-type-badge{background:#c7d2fe;color:#1e3a8a}\n.pm-type-head.t3 .pm-type-badge{background:#e2e8f0;color:#1e293b}\n.pm-type-head.t4 .pm-type-badge{background:#a7f3d0;color:#064e3b}\n.pm-type-head.t5 .pm-type-badge{background:#bae6fd;color:#0c4a6e}\n.pm-type-body{padding:13px 16px;background:#f8fafc;font-size:13px;color:#4b5563;line-height:1.6}\n.pm-type-body .spec-row{display:flex;justify-content:space-between;padding:5px 0;border-bottom:1px solid #f1f5f9;font-size:13px}\n.pm-type-body .spec-row:last-child{border-bottom:none}\n.pm-type-body .spec-label{color:#64748b}\n.pm-type-body .spec-val{font-weight:700;color:#111827}\n\n\/* \u2500\u2500 TEST REQUIREMENT TABLE CARDS \u2500\u2500 *\/\n.pm-test-grid{display:grid;grid-template-columns:1fr;gap:0;margin:24px 0;border:1px solid #e2e8f0;border-radius:8px;overflow:hidden}\n.pm-test-row{display:grid;grid-template-columns:1.4fr 1fr 1.8fr 1fr;border-bottom:1px solid #f1f5f9}\n.pm-test-row:last-child{border-bottom:none}\n.pm-test-row.hdr{background:#1e1b4b}\n.pm-test-cell{padding:11px 14px;font-size:13.5px;color:#374151;vertical-align:top}\n.pm-test-row.hdr .pm-test-cell{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.1em;color:#a5b4fc}\n.pm-test-row:nth-child(even):not(.hdr){background:#fafafa}\n.pm-test-cell.param{font-weight:600;color:#111827}\n.pm-pass{display:inline-block;font-size:11px;font-weight:700;background:#dcfce7;color:#166534;padding:1px 7px;border-radius:20px}\n.pm-meas{display:inline-block;font-size:11px;font-weight:700;background:#dbeafe;color:#1e40af;padding:1px 7px;border-radius:20px}\n\n\/* \u2500\u2500 COC ANATOMY \u2500\u2500 *\/\n.pm-coc-layout{background:#f8fafc;border:1px solid #e2e8f0;border-radius:8px;padding:24px;margin:24px 0;font-family:monospace;font-size:13px;line-height:1.7}\n.pm-coc-header{background:#1e1b4b;color:#e0e7ff;padding:10px 16px;border-radius:4px;margin-bottom:16px;font-size:12px;font-weight:700;letter-spacing:.05em}\n.pm-coc-section{margin-bottom:14px;padding-bottom:14px;border-bottom:1px dashed #d1d5db}\n.pm-coc-section:last-child{border-bottom:none;margin-bottom:0;padding-bottom:0}\n.pm-coc-label{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.1em;color:#6b7280;margin-bottom:4px}\n.pm-coc-value{color:#111827;font-size:13.5px}\n.pm-coc-value.good{color:#15803d;font-weight:700}\n.pm-coc-value.bad{color:#dc2626;text-decoration:line-through}\n.pm-coc-note{font-size:11.5px;color:#6b7280;font-family:sans-serif;margin-top:2px}\n\n\/* \u2500\u2500 COMPLIANCE FLOWCHART \u2500\u2500 *\/\n.pm-flow{display:flex;flex-direction:column;gap:0;margin:24px 0}\n.pm-flow-step{display:flex;gap:0;align-items:stretch}\n.pm-flow-left{display:flex;flex-direction:column;align-items:center;width:44px;flex-shrink:0}\n.pm-flow-dot{width:34px;height:34px;background:#3730a3;border-radius:50%;display:flex;align-items:center;justify-content:center;color:#fff;font-size:13px;font-weight:700;flex-shrink:0;z-index:1}\n.pm-flow-line{width:2px;flex:1;background:#c7d2fe;margin:4px 0}\n.pm-flow-body{padding:2px 0 22px 14px;flex:1}\n.pm-flow-body h4{font-size:15px;font-weight:700;color:#111827;margin:0 0 5px}\n.pm-flow-body p{font-size:14px;color:#4b5563;margin:0;line-height:1.7}\n.pm-flow-step:last-child .pm-flow-line{visibility:hidden}\n\n\/* \u2500\u2500 BUYER DECISION MATRIX \u2500\u2500 *\/\n.pm-decision-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin:24px 0}\n.pm-decision-card{border-radius:6px;overflow:hidden}\n.pm-decision-head{padding:13px 18px;font-size:14px;font-weight:700}\n.pm-decision-head.yes{background:#1e1b4b;color:#e0e7ff}\n.pm-decision-head.no{background:#374151;color:#f9fafb}\n.pm-decision-body{background:#f8fafc;border:1px solid #e2e8f0;border-top:none;padding:14px 18px;font-size:13.5px;color:#374151;line-height:1.65}\n.pm-decision-body ul{margin:0;padding-left:16px}\n.pm-decision-body ul li{margin:6px 0}\n\n\/* \u2500\u2500 GENERAL TABLE \u2500\u2500 *\/\n.pm-table-wrap{overflow-x:auto;margin:24px 0;border:1px solid #e2e8f0;border-radius:6px}\n.pm-table-wrap table{width:100%;border-collapse:collapse;font-size:14px;min-width:460px}\n.pm-table-wrap thead tr{background:#f1f5f9}\n.pm-table-wrap th{font-size:11.5px;font-weight:700;text-transform:uppercase;letter-spacing:.1em;color:#475569;padding:12px 14px;text-align:left;border-bottom:1px solid #e2e8f0;white-space:nowrap}\n.pm-table-wrap td{padding:11px 14px;border-bottom:1px solid #f1f5f9;vertical-align:top;color:#374151;font-size:14px}\n.pm-table-wrap tbody tr:last-child td{border-bottom:none}\n.pm-table-wrap tbody tr:hover{background:#fafafa}\n.pm-table-wrap td:first-child{font-weight:600;color:#111827}\n\n\/* \u2500\u2500 FAQ \u2500\u2500 *\/\n.pm-faq-item{border-bottom:1px solid #f1f5f9;padding:18px 0}\n.pm-faq-item:last-child{border-bottom:none}\n.pm-faq-q{font-size:16px;font-weight:700;color:#111827;margin:0 0 8px}\n.pm-faq-a{font-size:15px;color:#4b5563;margin:0;line-height:1.7}\n\n\/* \u2500\u2500 CLUSTER LINKS \u2500\u2500 *\/\n.pm-cluster-group{margin:0 0 24px}\n.pm-cluster-label{font-size:11px;font-weight:700;text-transform:uppercase;letter-spacing:.12em;color:#94a3b8;margin:0 0 10px}\n.pm-cluster-group ul{list-style:none;padding:0;margin:0;display:flex;flex-direction:column;gap:4px}\n.pm-cluster-group ul li a{display:flex;align-items:center;gap:8px;color:#3730a3;text-decoration:none;font-size:14.5px;padding:8px 12px;border:1px solid #e2e8f0;border-radius:4px;background:#fafafa}\n.pm-cluster-group ul li a:hover{background:#f0f4ff;border-color:#c7d2fe}\n.pm-cluster-group ul li a::before{content:\"\u2192\";font-weight:700;flex-shrink:0}\n\n.pm-section-divider{border:none;border-top:1px solid #f1f5f9;margin:48px 0}\n\n@media(max-width:680px){\n  .pm-test-row{grid-template-columns:1fr 1fr}\n  .pm-test-cell:nth-child(3){display:none}\n  .pm-test-row.hdr .pm-test-cell:nth-child(3){display:none}\n  .pm-decision-grid{grid-template-columns:1fr}\n}\n@media(max-width:480px){\n  .pm-anatomy-grid{grid-template-columns:1fr}\n  .pm-type-grid{grid-template-columns:1fr}\n  .pm-test-row{grid-template-columns:1fr}\n  .pm-test-cell:nth-child(2),.pm-test-cell:nth-child(4){display:none}\n  .pm-test-row.hdr .pm-test-cell:nth-child(2),\n  .pm-test-row.hdr .pm-test-cell:nth-child(4){display:none}\n}\n<\/style>\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     INTRO\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h1>Mil-Spec Plastic Media: What MIL-P-85891A Means for Buyers<\/h1>\n<p>MIL-P-85891A is a four-letter shorthand that appears constantly in aerospace blast media purchasing \u2014 on purchase orders, process specifications, quality records, and supplier certifications. Most buyers who encounter it know that it means something important about the media they are buying, but few have actually read the document or understand what its requirements mean in concrete terms: what properties it specifies, what testing it requires, what the type and class designations mean, and critically, how to verify that a supplier&#8217;s &#8220;MIL-P-85891A compliant&#8221; claim is genuine rather than a marketing label attached to untested commercial-grade product.<\/p>\n\n<p>This guide decodes MIL-P-85891A completely. It covers the document&#8217;s structure, every physical and chemical requirement it specifies with the actual limit values, what a genuinely compliant Certificate of Conformance must contain, the type and class designation system and what each combination means for purchasing, the difference between a compliant product and a &#8220;per specification&#8221; marketing claim, and exactly when MIL-P-85891A compliance is legally and contractually required versus when it is optional but prudent. By the end, you will be able to read a supplier&#8217;s CoC and know immediately whether it demonstrates genuine MIL-spec compliance or whether it is a conformance statement with no underlying substance.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=\"#mil-what\">What MIL-P-85891A Is and Why It Exists<\/a><\/li>\n    <li><a href=\"#mil-structure\">Document Structure: What the Spec Actually Contains<\/a><\/li>\n    <li><a href=\"#mil-types\">Type and Class Designation System<\/a><\/li>\n    <li><a href=\"#mil-requirements\">Every Physical Requirement \u2014 With the Actual Limit Values<\/a><\/li>\n    <li><a href=\"#mil-testing\">Testing Methods: How Each Property Is Measured<\/a><\/li>\n    <li><a href=\"#mil-coc\">What a Genuine Compliant CoC Must Contain<\/a><\/li>\n    <li><a href=\"#mil-fake\">How to Spot a Non-Compliant &#8220;MIL-Spec&#8221; Claim<\/a><\/li>\n    <li><a href=\"#mil-when\">When MIL-P-85891A Is Required vs. Optional<\/a><\/li>\n    <li><a href=\"#mil-qualified\">Qualified Products List (QPL): What It Is and Whether You Need It<\/a><\/li>\n    <li><a href=\"#mil-flow\">Compliance Flow: From Process Spec to Purchase Order<\/a><\/li>\n    <li><a href=\"#mil-superseded\">Has MIL-P-85891A Been Superseded? Current Document Status<\/a><\/li>\n    <li><a href=\"#mil-faq\">Preguntas frecuentes<\/a><\/li>\n    <li><a href=\"#mil-related\">Related Guides<\/a><\/li>\n  <\/ol>\n<\/nav>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S1 \u2014 WHAT IT IS\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-what\">What MIL-P-85891A Is and Why It Exists<\/h2>\n\n<p>MIL-P-85891A is a United States military performance specification issued by the Department of Defense (DoD), specifically under the Naval Air Systems Command (NAVAIR). Its full title is <em>Plastic Media, Blasting, Cleaning and Paint Stripping<\/em>. The &#8220;A&#8221; suffix designates the first revision to the original MIL-P-85891 document. It is a performance specification \u2014 meaning it defines the required properties of the end product (the media) rather than specifying the manufacturing process used to make it.<\/p>\n\n<p>The specification exists because plastic blast media was developed specifically for aerospace depainting applications where the substrate \u2014 primarily aluminum aircraft structure \u2014 cannot tolerate the surface damage that mineral abrasives (silica sand, aluminum oxide) cause. Before plastic media and its governing specification existed, aerospace depainting relied on chemical strippers with significant environmental and health hazards. The military needed a mechanical stripping method that was environmentally preferable, faster, and controllable \u2014 and the specification was written to ensure that any media marketed for this purpose actually had the properties needed to strip coatings without damaging the aircraft structure.<\/p>\n\n<p>Today MIL-P-85891A is the de facto industry standard for any high-quality plastic blast media, used well beyond its original military context. Commercial aerospace MRO, industrial manufacturing, and precision finishing operations specify it because it provides the most complete set of documented property requirements available for this material category \u2014 not because their customer is the U.S. Navy.<\/p>\n\n<div class=\"pm-callout\">\n  <strong>A performance spec, not a process spec:<\/strong> MIL-P-85891A tells manufacturers what the media must be, not how to make it. This means two manufacturers using completely different polymer processing routes can both produce MIL-P-85891A compliant media \u2014 as long as their output meets all the specification requirements. The buyer&#8217;s responsibility is to verify compliance through the CoC and incoming inspection, not to audit the manufacturing process.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S2 \u2014 DOCUMENT STRUCTURE\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-structure\">Document Structure: What the Spec Actually Contains<\/h2>\n\n<p>MIL-P-85891A is organized into six sections. Understanding what each section covers helps buyers navigate the document and understand which sections are most relevant to purchasing and quality verification.<\/p>\n\n<div class=\"pm-anatomy-grid\">\n  <div class=\"pm-anatomy-card\">\n    <div class=\"pm-anatomy-head\">\ud83d\udccb Section 1: Scope<\/div>\n    <div class=\"pm-anatomy-body\">\n      Defines the purpose and intended application of the specification. States that the specification covers plastic media for blasting, cleaning, and paint stripping from metallic and composite substrates. Establishes that the spec applies to media used in pressure blasting systems at pressures not to exceed 80 PSI.\n    <\/div>\n  <\/div>\n  <div class=\"pm-anatomy-card\">\n    <div class=\"pm-anatomy-head\">\ud83d\udcda Section 2: Applicable Documents<\/div>\n    <div class=\"pm-anatomy-body\">\n      Lists all referenced documents \u2014 other military specifications, ASTM standards, and test methods that are incorporated by reference. Critical for understanding which test methods apply to each property measurement.\n    <\/div>\n  <\/div>\n  <div class=\"pm-anatomy-card\">\n    <div class=\"pm-anatomy-head\">\u2697\ufe0f Section 3: Requirements<\/div>\n    <div class=\"pm-anatomy-body\">\n      The technical core of the document. Contains all property requirements: type\/class definitions, particle size limits, hardness requirements, moisture content limit, pH range, bulk density requirements, and composition requirements. This is the section that CoC values must demonstrate compliance with.\n    <\/div>\n  <\/div>\n  <div class=\"pm-anatomy-card\">\n    <div class=\"pm-anatomy-head\">\ud83d\udd2c Section 4: Quality Assurance Provisions<\/div>\n    <div class=\"pm-anatomy-body\">\n      Specifies the inspection and testing requirements \u2014 what tests must be performed on each lot, the test methods to use, and the sampling requirements. Distinguishes between lot acceptance tests (every lot) and qualification tests (performed once to establish the product on the Qualified Products List).\n    <\/div>\n  <\/div>\n  <div class=\"pm-anatomy-card\">\n    <div class=\"pm-anatomy-head\">\ud83d\udce6 Section 5: Packaging<\/div>\n    <div class=\"pm-anatomy-body\">\n      Specifies packaging requirements including marking, labeling, and container requirements. Establishes the information that must appear on each container: manufacturer name, specification number, type, class, lot number, quantity, date of manufacture, and net weight.\n    <\/div>\n  <\/div>\n  <div class=\"pm-anatomy-card\">\n    <div class=\"pm-anatomy-head\">\ud83d\udcdd Section 6: Notes<\/div>\n    <div class=\"pm-anatomy-body\">\n      Guidance notes for ordering and use. Contains the ordering data requirements \u2014 the information that must be included in a purchase order to fully define the required product. Also provides guidance on intended use and application parameters.\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S3 \u2014 TYPE AND CLASS SYSTEM\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-types\">Type and Class Designation System<\/h2>\n\n<p>MIL-P-85891A organizes plastic blast media into five Types based on polymer chemistry and two Classes based on particle shape. Every fully specified MIL-spec purchase order must state both Type and Class.<\/p>\n\n<h3>The Five Types<\/h3>\n\n<div class=\"pm-type-grid\">\n  <div class=\"pm-type-card\">\n    <div class=\"pm-type-head t1\">Type I \u2014 Polyester <span class=\"pm-type-badge\">Rare<\/span><\/div>\n    <div class=\"pm-type-body\">\n      Thermosetting polyester resin. Rarely specified in current practice \u2014 superseded in most applications by Type II for general coating removal. Some legacy aerospace process documents still reference Type I; verify current applicability with your process engineer.\n      <div class=\"spec-row\"><span class=\"spec-label\">Market availability<\/span><span class=\"spec-val\">Very limited<\/span><\/div>\n      <div class=\"spec-row\"><span class=\"spec-label\">Mohs hardness<\/span><span class=\"spec-val\">~3.0<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-type-card\">\n    <div class=\"pm-type-head t2\">Type II \u2014 Urea Formaldehyde <span class=\"pm-type-badge\">Most Common<\/span><\/div>\n    <div class=\"pm-type-body\">\n      Thermosetting urea formaldehyde. The dominant type \u2014 accounts for approximately 70\u201375% of all plastic blast media sold. Standard for aerospace aluminum, automotive, and general industrial coating removal.\n      <div class=\"spec-row\"><span class=\"spec-label\">Mohs hardness<\/span><span class=\"spec-val\">~3.5<\/span><\/div>\n      <div class=\"spec-row\"><span class=\"spec-label\">pH requirement<\/span><span class=\"spec-val\">7.0\u20139.0<\/span><\/div>\n      <div class=\"spec-row\"><span class=\"spec-label\">MIL-P-85891A Section<\/span><span class=\"spec-val\">3.2.2<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-type-card\">\n    <div class=\"pm-type-head t3\">Type III \u2014 Melamine Formaldehyde <span class=\"pm-type-badge\">Heavy Duty<\/span><\/div>\n    <div class=\"pm-type-body\">\n      Thermosetting melamine formaldehyde. Harder than Type II \u2014 used for more aggressive coating removal where Type II strip rate is insufficient. Titanium structure, heavy industrial coatings, rubberized underseal.\n      <div class=\"spec-row\"><span class=\"spec-label\">Mohs hardness<\/span><span class=\"spec-val\">~4.0<\/span><\/div>\n      <div class=\"spec-row\"><span class=\"spec-label\">MIL-P-85891A Section<\/span><span class=\"spec-val\">3.2.3<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-type-card\">\n    <div class=\"pm-type-head t4\">Type IV \u2014 Phenolic <span class=\"pm-type-badge\">Specialty<\/span><\/div>\n    <div class=\"pm-type-body\">\n      Thermosetting phenolic resin. Harder than Types I\u2013III. Limited applications \u2014 some rubber-lined equipment cleaning, specific industrial depainting where Type III hardness is still insufficient. Rarely specified.\n      <div class=\"spec-row\"><span class=\"spec-label\">Mohs hardness<\/span><span class=\"spec-val\">~4.5<\/span><\/div>\n      <div class=\"spec-row\"><span class=\"spec-label\">Market availability<\/span><span class=\"spec-val\">Limited<\/span><\/div>\n    <\/div>\n  <\/div>\n  <div class=\"pm-type-card\">\n    <div class=\"pm-type-head t5\">Type V \u2014 Acrylic (PMMA) <span class=\"pm-type-badge\">Precision<\/span><\/div>\n    <div class=\"pm-type-body\">\n      Thermoplastic PMMA (polymethyl methacrylate). Softest type \u2014 required for CFRP and composite depainting, mold cleaning, electronics deflashing, and any precision application where substrate damage risk is the primary constraint.\n      <div class=\"spec-row\"><span class=\"spec-label\">Mohs hardness<\/span><span class=\"spec-val\">~3.0<\/span><\/div>\n      <div class=\"spec-row\"><span class=\"spec-label\">MIL-P-85891A Section<\/span><span class=\"spec-val\">3.2.5<\/span><\/div>\n    <\/div>\n  <\/div>\n<\/div>\n\n<h3>The Two Classes<\/h3>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Class<\/th>\n        <th>Descripci\u00f3n<\/th>\n        <th>Forma de las part\u00edculas<\/th>\n        <th>When Specified<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Class 1<\/td>\n        <td>Irregular angular particles<\/td>\n        <td>Angular, irregular \u2014 sharp edges and corners; the standard blast media form<\/td>\n        <td>All coating removal, surface preparation, and deflashing applications. The default class for the vast majority of applications. If not otherwise specified, assume Class 1.<\/td>\n      <\/tr>\n      <tr>\n        <td>Class 2<\/td>\n        <td>Spherical or rounded particles<\/td>\n        <td>Round to sub-round \u2014 reduced angularity; some specialized applications requiring lower surface profile impact<\/td>\n        <td>Specialty applications where reduced surface profile is required along with low substrate hardness. Rarely specified in practice; most peening applications use glass bead rather than Class 2 plastic media.<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<h3>Correct Ordering Designation Format<\/h3>\n<p>A fully specified MIL-P-85891A purchase order designation reads: <strong>MIL-P-85891A, Type [Roman numeral], Class [Arabic numeral], Mesh [size]<\/strong>. Example: &#8220;MIL-P-85891A, Type II, Class 1, Mesh 20-30.&#8221; Any purchase order that omits Type, Class, or mesh size is ambiguous and gives the supplier latitude to ship a product that may not match your 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\n     S4 \u2014 EVERY REQUIREMENT\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-requirements\">Every Physical Requirement \u2014 With the Actual Limit Values<\/h2>\n\n<p>This is the section of MIL-P-85891A that most buyers never read directly but need to understand to evaluate CoC compliance. The following covers every property requirement in Section 3 of the specification with the actual limit values as written in the document.<\/p>\n\n<h3>Particle Size Distribution (Section 3.3)<\/h3>\n\n<p>The particle size distribution requirement is the most detailed and most frequently checked requirement in the specification. For each nominal mesh designation, MIL-P-85891A specifies the minimum percentage of particles that must be retained on a series of standard ASTM sieves. The specification sets limits in both directions: a maximum for oversize particles (which would indicate insufficient classification on the upper end) and a minimum for the primary fraction (which defines the tightness of the size distribution).<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Nominal Mesh Designation<\/th>\n        <th>Maximum Retained on Upper Screen<\/th>\n        <th>Minimum Retained on Nominal Screen<\/th>\n        <th>Maximum Passing Lower Screen<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Mesh 14 (14\/20)<\/td>\n        <td>5% max on No. 10 screen<\/td>\n        <td>90% min on No. 14 screen<\/td>\n        <td>5% max passing No. 20 screen<\/td>\n      <\/tr>\n      <tr>\n        <td>Mesh 20 (20\/30)<\/td>\n        <td>5% max on No. 14 screen<\/td>\n        <td>90% min on No. 20 screen<\/td>\n        <td>5% max passing No. 30 screen<\/td>\n      <\/tr>\n      <tr>\n        <td>Mesh 30 (30\/40)<\/td>\n        <td>5% max on No. 20 screen<\/td>\n        <td>90% min on No. 30 screen<\/td>\n        <td>5% max passing No. 40 screen<\/td>\n      <\/tr>\n      <tr>\n        <td>Mesh 40 (40\/50)<\/td>\n        <td>5% max on No. 30 screen<\/td>\n        <td>90% min on No. 40 screen<\/td>\n        <td>5% max passing No. 50 screen<\/td>\n      <\/tr>\n      <tr>\n        <td>Mesh 50 (50\/60)<\/td>\n        <td>5% max on No. 40 screen<\/td>\n        <td>90% min on No. 50 screen<\/td>\n        <td>5% max passing No. 60 screen<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<p>The critical design intent: at least 90% of the media must be retained on the nominal screen, with no more than 5% oversize (retained on the next coarser screen) and no more than 5% undersize (passing the next finer screen). This 90\/5\/5 distribution is significantly tighter than most commercial-grade media specifications, which often allow 80% on the nominal screen and 10% each for over- and undersize. The tighter distribution produces more consistent blast performance because the energy per particle impact varies with particle size \u2014 a wide distribution means high-energy large particles and low-energy small particles blasting simultaneously, producing uneven results.<\/p>\n\n<h3>All Physical and Chemical Requirements at a Glance<\/h3>\n\n<div class=\"pm-test-grid\">\n  <div class=\"pm-test-row hdr\">\n    <div class=\"pm-test-cell\">Property<\/div>\n    <div class=\"pm-test-cell\">Requirement \/ Limit Value<\/div>\n    <div class=\"pm-test-cell\">Significance for Blast Performance<\/div>\n    <div class=\"pm-test-cell\">CoC Evidence<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">Distribuci\u00f3n granulom\u00e9trica<\/div>\n    <div class=\"pm-test-cell\">\u226590% retained on nominal screen; \u22645% oversize; \u22645% undersize<\/div>\n    <div class=\"pm-test-cell\">Tight distribution = consistent impact energy per particle = predictable, uniform surface results. Loose distribution = inconsistent results, higher dust.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-meas\">Measured<\/span> Sieve retention % on each screen must appear as actual numbers<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">Moisture content (all types)<\/div>\n    <div class=\"pm-test-cell\">Maximum 1.0% by weight<\/div>\n    <div class=\"pm-test-cell\">Moisture above 1% causes flow irregularity, pot bridging, reduced strip rate, and can indicate media degradation. Critical for consistent blast pot operation.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-meas\">Measured<\/span> Actual % must be stated (e.g., &#8220;0.47%&#8221;), not just &#8220;\u22641.0%&#8221;<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">pH (Type II Urea only)<\/div>\n    <div class=\"pm-test-cell\">7.0 to 9.0<\/div>\n    <div class=\"pm-test-cell\">pH outside this range indicates contamination or degradation of the urea formaldehyde matrix. Low pH (acidic) can indicate acid contamination that accelerates aluminum oxidation after blasting.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-meas\">Measured<\/span> Actual pH value (e.g., &#8220;8.1&#8221;) must appear; not just &#8220;within range&#8221;<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">Densidad aparente<\/div>\n    <div class=\"pm-test-cell\">Type-specific ranges: Type II ~45\u201355 lb\/ft\u00b3; Type V ~38\u201348 lb\/ft\u00b3 (exact limits in Table I of specification)<\/div>\n    <div class=\"pm-test-cell\">Density affects mass flow rate through the blast pot metering system and kinetic energy per particle at blast velocity. Ensures the media is the expected polymer type, not a substitute.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-meas\">Measured<\/span> Actual lb\/ft\u00b3 value required<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">Dureza<\/div>\n    <div class=\"pm-test-cell\">Type-specific Mohs ranges: Type II 3.0\u20134.0; Type III 3.5\u20134.5; Type V 2.5\u20133.5<\/div>\n    <div class=\"pm-test-cell\">Hardness determines the ratio of coating removal to substrate damage. Media that is too hard erodes substrate; too soft fails to remove coating efficiently.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-meas\">Measured<\/span> Actual Mohs value or equivalent required<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">Composition \/ chemistry<\/div>\n    <div class=\"pm-test-cell\">Must be the polymer type specified (Type I\u2013V). No heavy metals, no free silica, no substances that would contaminate the substrate surface or create environmental\/health hazards beyond those already addressed in the specification.<\/div>\n    <div class=\"pm-test-cell\">Prevents substitution of cheaper non-conforming polymers or mineral abrasive material into the media charge. Protects substrate from unexpected contamination.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-pass\">Conformance<\/span> Statement of polymer type; MSDS confirming absence of regulated substances<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">No sharp metallic particles<\/div>\n    <div class=\"pm-test-cell\">Media must not contain metallic particles that could score substrate surfaces or introduce iron contamination<\/div>\n    <div class=\"pm-test-cell\">Metallic particles from manufacturing equipment contamination would score aluminum and titanium surfaces and introduce galvanic corrosion nuclei in aerospace structure.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-pass\">Conformance<\/span> Statement of no metallic particle contamination<\/div>\n  <\/div>\n  <div class=\"pm-test-row\">\n    <div class=\"pm-test-cell param\">Particle shape (Class 1)<\/div>\n    <div class=\"pm-test-cell\">Class 1: angular\/irregular; Class 2: spherical\/rounded<\/div>\n    <div class=\"pm-test-cell\">Angular shape provides stress concentration for coating adhesion bond fracture. Rounded particles (Class 2) produce peening rather than cutting \u2014 different blast mechanism for different applications.<\/div>\n    <div class=\"pm-test-cell\"><span class=\"pm-pass\">Conformance<\/span> Class statement on CoC<\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S5 \u2014 TESTING METHODS\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-testing\">Testing Methods: How Each Property Is Measured<\/h2>\n\n<p>MIL-P-85891A Section 4 specifies the test methods to be used for each property. A CoC from a compliant supplier references these methods (or their commercial equivalents) to demonstrate that testing was conducted correctly. Understanding the test methods also helps you evaluate whether a supplier&#8217;s internal testing is genuinely equivalent to the specification-required methods.<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>Property<\/th>\n        <th>Specified Test Method<\/th>\n        <th>What the Test Measures<\/th>\n        <th>In-House vs. Third-Party<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Distribuci\u00f3n granulom\u00e9trica<\/td>\n        <td>ASTM E11 sieves; mechanical sieve shaker with defined agitation time and sample weight<\/td>\n        <td>Percentage by weight retained on each screen in the test series; completed for at least the three screens spanning the nominal mesh (one coarser, nominal, one finer)<\/td>\n        <td>In-house \u2014 requires calibrated sieves and sieve shaker; minimal equipment investment; can be done quickly per lot<\/td>\n      <\/tr>\n      <tr>\n        <td>Moisture content<\/td>\n        <td>Gravimetric method: weigh sample, dry at 220\u00b0F (104\u00b0C) for 2 hours, reweigh; moisture % = weight loss\/initial weight \u00d7 100<\/td>\n        <td>Total moisture present in the media as a percentage of total weight; measures both surface moisture and absorbed moisture<\/td>\n        <td>In-house \u2014 requires precision balance and drying oven; simple and fast; should be performed on every lot before release<\/td>\n      <\/tr>\n      <tr>\n        <td>pH (Type II Urea)<\/td>\n        <td>Media-water paste tested with calibrated pH meter per ASTM E70 or equivalent<\/td>\n        <td>Acidity or alkalinity of the media surface chemistry; determines whether the urea formaldehyde matrix has been compromised by acid contamination or degradation<\/td>\n        <td>In-house \u2014 calibrated pH meter required; straightforward procedure; per lot<\/td>\n      <\/tr>\n      <tr>\n        <td>Densidad aparente<\/td>\n        <td>ASTM B329 or equivalent; fill a known volume container with media by a standardized pour method; calculate lb\/ft\u00b3 from weight<\/td>\n        <td>Apparent bulk density \u2014 confirms the media is the expected polymer type and that density-altering substitution or contamination has not occurred<\/td>\n        <td>In-house \u2014 requires calibrated scale and standard measure; quick; per lot<\/td>\n      <\/tr>\n      <tr>\n        <td>Dureza<\/td>\n        <td>Mohs scratch hardness or Vickers microhardness equivalent; some specifications accept Shore D hardness correlation with Mohs range<\/td>\n        <td>Resistance of the particle to plastic deformation \u2014 determines the upper boundary of substrate materials that can be safely blasted without surface damage<\/td>\n        <td>In-house or third-party; requires hardness tester; often tested quarterly per production batch rather than every lot<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<div class=\"pm-callout pm-callout-green\">\n  <strong>Lot frequency vs. qualification frequency:<\/strong> MIL-P-85891A distinguishes between lot acceptance tests (performed on every production lot before it can be shipped with a compliant CoC) and qualification tests (performed once to place the product on the QPL). Particle size distribution, moisture content, and pH are lot acceptance tests \u2014 they must be performed every lot. Hardness and bulk density are typically verified at the qualification stage and then periodically (not necessarily every lot) once the product is established. When evaluating a CoC, particle size, moisture, and pH must always be measured values; hardness and density may reference the qualification test record rather than a new per-lot measurement.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S6 \u2014 CoC ANATOMY\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-coc\">What a Genuine Compliant CoC Must Contain<\/h2>\n\n<p>The Certificate of Conformance is the primary quality document for each lot of plastic blast media. For a CoC to demonstrate genuine MIL-P-85891A compliance, it must contain specific elements \u2014 not just a conformance statement. Below is an annotated example of a compliant CoC vs. common non-compliant variations.<\/p>\n\n<div class=\"pm-coc-layout\">\n  <div class=\"pm-coc-header\">\ud83d\udccb CERTIFICATE OF CONFORMANCE \u2014 ANNOTATED EXAMPLE<\/div>\n\n  <div class=\"pm-coc-section\">\n    <div class=\"pm-coc-label\">Specification Reference<\/div>\n    <div class=\"pm-coc-value good\">\u2705 MIL-P-85891A, Type II, Class 1<\/div>\n    <div class=\"pm-coc-note\">Must cite the full spec number AND revision letter (the &#8220;A&#8221;) AND type AND class. &#8220;Meets plastic media spec&#8221; is not sufficient.<\/div>\n    <div class=\"pm-coc-value bad\">\u274c &#8220;Meets applicable specification for plastic blast media&#8221;<\/div>\n  <\/div>\n\n  <div class=\"pm-coc-section\">\n    <div class=\"pm-coc-label\">Lot Number + Manufacturing Date<\/div>\n    <div class=\"pm-coc-value good\">\u2705 Lot: 2024-11-0847 | Manufactured: November 2024<\/div>\n    <div class=\"pm-coc-note\">Unique, traceable lot number tied to a specific production batch. Manufacturing date (month + year minimum) required. Must match markings on the bags.<\/div>\n    <div class=\"pm-coc-value bad\">\u274c Lot: &#8220;Current production&#8221; | Date: not stated<\/div>\n  <\/div>\n\n  <div class=\"pm-coc-section\">\n    <div class=\"pm-coc-label\">Particle Size Distribution \u2014 REQUIRED ACTUAL VALUES<\/div>\n    <div class=\"pm-coc-value good\">\u2705 No. 14 screen (oversize): 1.2% retained (limit: \u22645%)<br>No. 20 screen (nominal): 94.1% retained (limit: \u226590%)<br>No. 30 screen (undersize): 2.3% passing (limit: \u22645%)<br>Test method: ASTM E11, 5-min mechanical shaker<\/div>\n    <div class=\"pm-coc-note\">Three actual percentage values required \u2014 one for each screen. &#8220;Passes particle size distribution&#8221; with no numbers is non-compliant.<\/div>\n    <div class=\"pm-coc-value bad\">\u274c &#8220;Particle size: meets Mesh 20-30 specification&#8221;<\/div>\n  <\/div>\n\n  <div class=\"pm-coc-section\">\n    <div class=\"pm-coc-label\">Moisture Content \u2014 REQUIRED ACTUAL VALUE<\/div>\n    <div class=\"pm-coc-value good\">\u2705 Moisture content: 0.38% (limit: \u22641.0%)<br>Test method: Gravimetric, 2 hr at 220\u00b0F<\/div>\n    <div class=\"pm-coc-note\">A specific measured percentage is required. &#8220;\u22641%&#8221; is the specification limit, not a test result \u2014 writing only the limit proves nothing.<\/div>\n    <div class=\"pm-coc-value bad\">\u274c &#8220;Moisture content: \u22641.0%&#8221; or &#8220;Dry&#8221;<\/div>\n  <\/div>\n\n  <div class=\"pm-coc-section\">\n    <div class=\"pm-coc-label\">pH (Type II Urea) \u2014 REQUIRED ACTUAL VALUE<\/div>\n    <div class=\"pm-coc-value good\">\u2705 pH: 8.2 (limit: 7.0\u20139.0)<br>Test method: ASTM E70, calibrated pH meter<\/div>\n    <div class=\"pm-coc-note\">Specific measured pH value required. Reporting only the specification range proves the test was not done or the result is being withheld.<\/div>\n    <div class=\"pm-coc-value bad\">\u274c &#8220;pH: 7.0\u20139.0&#8221; or &#8220;pH: within specification&#8221;<\/div>\n  <\/div>\n\n  <div class=\"pm-coc-section\">\n    <div class=\"pm-coc-label\">Certifying Signature<\/div>\n    <div class=\"pm-coc-value good\">\u2705 Signed by: [Name], Quality Manager, [Manufacturer Name] | Date: [specific date]<\/div>\n    <div class=\"pm-coc-note\">Must be signed by an authorized quality representative of the manufacturer \u2014 the party who performed the testing. Distributor signature alone (without underlying manufacturer data) is not adequate for regulated applications.<\/div>\n    <div class=\"pm-coc-value bad\">\u274c Unsigned; or signed only by distributor with no manufacturer test data attached<\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S7 \u2014 HOW TO SPOT FAKE CLAIMS\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-fake\">How to Spot a Non-Compliant &#8220;MIL-Spec&#8221; Claim<\/h2>\n\n<p>The most commercially consequential gap in the plastic blast media market is between suppliers who genuinely test and certify each lot to MIL-P-85891A requirements and suppliers who use &#8220;MIL-spec&#8221; as a marketing label without the underlying testing. The distinction is not always obvious from a sales conversation or a product data sheet \u2014 it becomes clear only when you examine the CoC. These are the specific markers that distinguish genuine compliance from a conformance claim:<\/p>\n\n<div class=\"pm-table-wrap\">\n  <table>\n    <thead>\n      <tr>\n        <th>CoC Element<\/th>\n        <th>Genuine MIL-P-85891A Compliance<\/th>\n        <th>Non-Compliant Marketing Claim<\/th>\n      <\/tr>\n    <\/thead>\n    <tbody>\n      <tr>\n        <td>Specification citation<\/td>\n        <td>&#8220;MIL-P-85891A, Type II, Class 1&#8221; \u2014 full document number with revision, type, and class<\/td>\n        <td>&#8220;Meets military specification&#8221; or &#8220;MIL-spec grade&#8221; without the document number<\/td>\n      <\/tr>\n      <tr>\n        <td>Particle size result<\/td>\n        <td>Three percentage values: oversize %, nominal screen %, undersize % \u2014 with the screen designations stated<\/td>\n        <td>&#8220;Particle size meets specification&#8221; or the nominal mesh designation with no percentages<\/td>\n      <\/tr>\n      <tr>\n        <td>Moisture content result<\/td>\n        <td>A specific measured percentage (e.g., &#8220;0.38%&#8221;) with test method cited<\/td>\n        <td>&#8220;\u22641.0%&#8221; (the specification limit, not a measurement) or &#8220;dry&#8221;<\/td>\n      <\/tr>\n      <tr>\n        <td>pH result (Type II)<\/td>\n        <td>A specific measured value (e.g., &#8220;8.2&#8221;) with test method cited<\/td>\n        <td>&#8220;7.0\u20139.0&#8221; (the specification range) or not stated<\/td>\n      <\/tr>\n      <tr>\n        <td>Lot traceability<\/td>\n        <td>Unique lot number tied to a specific production batch, matching bag markings; lot number cross-referenceable to actual production records<\/td>\n        <td>Generic lot number, date-based lot codes that apply to entire months of production, or no lot number<\/td>\n      <\/tr>\n      <tr>\n        <td>Certifying party<\/td>\n        <td>Signed by quality representative of the manufacturer with their company name and title<\/td>\n        <td>Signed only by the distributor; or signed by the distributor claiming manufacturer quality on their behalf without underlying test data<\/td>\n      <\/tr>\n      <tr>\n        <td>Test method reference<\/td>\n        <td>References ASTM or specification test methods (e.g., &#8220;ASTM E11 sieve analysis&#8221;) for each parameter<\/td>\n        <td>No test method reference; or &#8220;per our internal standard&#8221; without citing the underlying method<\/td>\n      <\/tr>\n    <\/tbody>\n  <\/table>\n<\/div>\n\n<div class=\"pm-callout pm-callout-danger\">\n  <strong>The practical test:<\/strong> Request the CoC before confirming an order. Tell the supplier: &#8220;Please send me a sample CoC for your most recent production lot of [Type, Class, Mesh] media so I can verify the documentation format before we place the order.&#8221; A supplier who cannot provide this, who sends a document with only conformance statements and no measured values, or who resists this request entirely is telling you everything you need to know about the actual compliance status of their product.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S8 \u2014 WHEN REQUIRED VS OPTIONAL\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-when\">When MIL-P-85891A Is Required vs. Optional<\/h2>\n\n<div class=\"pm-decision-grid\">\n  <div class=\"pm-decision-card\">\n    <div class=\"pm-decision-head yes\">\u2705 MIL-P-85891A IS REQUIRED when:<\/div>\n    <div class=\"pm-decision-body\">\n      <ul>\n        <li>The applicable process specification (e.g., Boeing BSS 7439, Airbus ABP 1-2061, Navy WS 6536, USAF TO 1-1-8) explicitly cites MIL-P-85891A as the governing media specification<\/li>\n        <li>The customer&#8217;s purchase order, contract, or statement of work requires media conformance to MIL-P-85891A by name<\/li>\n        <li>Your quality system (AS9100, Nadcap audit requirements) mandates full material traceability with lot-level CoC documentation, and no commercial equivalent specification provides equivalent coverage<\/li>\n        <li>The application involves U.S. military aircraft, military vehicles, or defense-related equipment subject to DoD quality requirements<\/li>\n        <li>An audit or quality authority has specifically required MIL-P-85891A-compliant media for the application<\/li>\n        <li>Your contract requires that all materials meet applicable military specifications, and no approved alternative is listed<\/li>\n      <\/ul>\n    <\/div>\n  <\/div>\n  <div class=\"pm-decision-card\">\n    <div class=\"pm-decision-head no\">\u2b1c MIL-P-85891A IS OPTIONAL (but often prudent) when:<\/div>\n    <div class=\"pm-decision-body\">\n      <ul>\n        <li>The application is commercial aerospace MRO where your process specification references &#8220;plastic blast media meeting the requirements of MIL-P-85891A&#8221; \u2014 the performance requirements apply, but no QPL qualification may be required<\/li>\n        <li>The application is industrial manufacturing, automotive restoration, or general industrial blasting where no military or aerospace specifications govern the process<\/li>\n        <li>Your customer has not specified a media specification but requires documented lot-level traceability \u2014 MIL-P-85891A compliance is the most comprehensive documentation framework available<\/li>\n        <li>You want to differentiate your quality management from competitors by demonstrating traceable material use, even without a regulatory requirement<\/li>\n        <li>You are qualifying a new blast process and want to establish a consistent baseline with the most rigorous available media specification before moving to less documented sources<\/li>\n      <\/ul>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S9 \u2014 QPL\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-qualified\">Qualified Products List (QPL): What It Is and Whether You Need It<\/h2>\n\n<p>The Qualified Products List (QPL-85891) is a DoD-maintained list of plastic blast media products and manufacturers that have undergone formal qualification testing by an independent laboratory to verify that their product meets all MIL-P-85891A requirements. Qualification is distinct from lot-level conformance: a manufacturer who is on the QPL has demonstrated that their manufacturing process can consistently produce compliant product, while lot-level CoC documentation demonstrates that a specific lot actually did meet the requirements.<\/p>\n\n<h3>When QPL Qualification Is Required<\/h3>\n<p>QPL qualification is explicitly required when the purchase order, contract, or process specification states &#8220;QPL-qualified product&#8221; or &#8220;product must be listed on QPL-85891.&#8221; This is most common in direct military procurement \u2014 orders placed by U.S. military facilities or prime contractors working under DFARS requirements. Commercial aerospace applications typically require &#8220;MIL-P-85891A compliant&#8221; media \u2014 meaning the properties must meet the specification requirements \u2014 without requiring QPL listing specifically. The distinction matters because QPL qualification has a cost and administrative burden for the manufacturer that is reflected in product pricing; if your application requires only specification compliance rather than QPL listing, you have a wider supplier selection.<\/p>\n\n<h3>How to Verify QPL Status<\/h3>\n<p>The current QPL-85891 is maintained by the Defense Logistics Agency (DLA) and can be accessed through the DLA&#8217;s online catalog system. When a supplier claims QPL qualification, ask for their QPL listing number and the product designation under which they are qualified. Cross-reference against the current published QPL before accepting the claim \u2014 QPL status must be maintained through periodic requalification testing, and manufacturers whose qualification has lapsed may not update their marketing materials immediately.<\/p>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S10 \u2014 COMPLIANCE FLOW\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-flow\">Compliance Flow: From Process Spec to Purchase Order<\/h2>\n\n<p>Understanding how MIL-P-85891A fits into the full compliance chain helps buyers trace the requirement back to its source and confirm whether their specific application genuinely requires MIL-spec media or whether a commercial equivalent is permissible.<\/p>\n\n<div class=\"pm-flow\">\n  <div class=\"pm-flow-step\">\n    <div class=\"pm-flow-left\"><div class=\"pm-flow-dot\">1<\/div><div class=\"pm-flow-line\"><\/div><\/div>\n    <div class=\"pm-flow-body\">\n      <h4>Governing Technical Requirement (Customer \/ Aircraft OEM \/ Military Authority)<\/h4>\n      <p>The chain starts with the governing process document \u2014 the Boeing process specification, Airbus engineering order, USAF technical order, or equivalent document that defines how a specific coating removal or surface preparation operation must be performed on a specific aircraft or component. This document either specifies MIL-P-85891A by name (making it a hard requirement) or specifies performance requirements that MIL-P-85891A media meets (making it a compliant choice among possibly others).<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-flow-step\">\n    <div class=\"pm-flow-left\"><div class=\"pm-flow-dot\">2<\/div><div class=\"pm-flow-line\"><\/div><\/div>\n    <div class=\"pm-flow-body\">\n      <h4>Maintenance Organization \/ MRO Process Specification<\/h4>\n      <p>The MRO or manufacturing facility translates the governing technical requirement into their own process specification or work instruction. This document specifies the approved media type, the blast parameters, the qualification requirements, and the documentation requirements for each blast operation. If the governing authority&#8217;s document references MIL-P-85891A, the facility&#8217;s process specification should echo that requirement.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-flow-step\">\n    <div class=\"pm-flow-left\"><div class=\"pm-flow-dot\">3<\/div><div class=\"pm-flow-line\"><\/div><\/div>\n    <div class=\"pm-flow-body\">\n      <h4>Quality System Material Requirements<\/h4>\n      <p>The facility&#8217;s quality system (typically AS9100 or equivalent) requires that all materials used in regulated processes be procured with documented traceability \u2014 lot number, manufacturer, CoC with measured test results. The quality system establishes the incoming inspection requirements and the records retention requirements for material CoCs. This is where the CoC format requirements become enforceable internal quality policy.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-flow-step\">\n    <div class=\"pm-flow-left\"><div class=\"pm-flow-dot\">4<\/div><div class=\"pm-flow-line\"><\/div><\/div>\n    <div class=\"pm-flow-body\">\n      <h4>Purchasing Specification on the Purchase Order<\/h4>\n      <p>The purchasing department translates all of the above into a purchase order with a complete material specification: &#8220;MIL-P-85891A, Type II, Class 1, Mesh 20-30, with CoC containing actual measured lot test values for particle size distribution, moisture content, and pH. QPL qualification required \/ not required [specify].&#8221; The completeness of the PO specification determines what the supplier delivers and what documentation they must provide.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-flow-step\">\n    <div class=\"pm-flow-left\"><div class=\"pm-flow-dot\">5<\/div><div class=\"pm-flow-line\"><\/div><\/div>\n    <div class=\"pm-flow-body\">\n      <h4>Supplier CoC and Lot Release<\/h4>\n      <p>The supplier tests the lot per the specification&#8217;s lot acceptance requirements, generates a CoC with the actual measured values, and ships the media with the CoC. The CoC becomes the primary quality record linking the specific lot of media to the specific blast operation records maintained by the facility.<\/p>\n    <\/div>\n  <\/div>\n  <div class=\"pm-flow-step\">\n    <div class=\"pm-flow-left\"><div class=\"pm-flow-dot\">6<\/div><div class=\"pm-flow-line\"><\/div><\/div>\n    <div class=\"pm-flow-body\">\n      <h4>Receiving Inspection and Quality Record Retention<\/h4>\n      <p>The facility&#8217;s quality system performs incoming inspection (field checks per their receiving inspection procedure) and files the CoC against the purchase order and the work order for the blast operation where the lot was used. These records are retained for the period specified by the governing quality system \u2014 typically 7\u201310 years for aerospace quality records, longer for life-limited part records. In the event of an audit or investigation, this traceability chain from the CoC through to the work order and the aircraft maintenance record is the documented evidence that the correct, specified material was used.<\/p>\n    <\/div>\n  <\/div>\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     S11 \u2014 DOCUMENT STATUS\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-superseded\">Has MIL-P-85891A Been Superseded? Current Document Status<\/h2>\n\n<p>MIL-P-85891A was issued under the DoD&#8217;s military specification system and is classified as an &#8220;active&#8221; specification \u2014 meaning it has not been formally cancelled or superseded by a newer document as of the most recent review. Unlike many Cold War-era military specifications that were cancelled during the 1990s DoD acquisition reform (MIL-SPEC Reform), MIL-P-85891A survived as an active specification because no commercial standard fully covers its scope, and because it governs a process (aircraft depainting) that remains active in military aviation maintenance.<\/p>\n\n<p>However, buyers should be aware of two nuances. First, the DoD periodically reviews military specifications for continued need, and the status of MIL-P-85891A should be verified against the current DLA ASSIST database before relying on it for a new contract or process qualification. Second, some commercial aerospace process specifications have begun referencing the media&#8217;s performance requirements using their own internal specification language rather than MIL-P-85891A directly \u2014 in these cases, the requirements are typically equivalent to MIL-P-85891A but the document citation differs. When in doubt about the current document status or the relationship between your process specification&#8217;s media requirements and MIL-P-85891A, consult the DLA ASSIST document database or your organization&#8217;s technical library.<\/p>\n\n<div class=\"pm-callout pm-callout-gray\">\n  <strong>Current status as of 2024:<\/strong> MIL-P-85891A remains an active DoD specification. It has not been superseded, cancelled, or converted to a commercial standard. The specification is available through the DLA ASSIST database (assist.dla.mil) at no charge. Always reference the DLA ASSIST database for the current revision status before citing this document in a new process specification or purchase contract.\n<\/div>\n\n<hr class=\"pm-section-divider\">\n\n\n<!-- \u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n     FAQ\n\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550 -->\n<h2 id=\"mil-faq\">Preguntas frecuentes<\/h2>\n\n<div itemscope itemtype=\"https:\/\/schema.org\/FAQPage\">\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">Does &#8220;meets MIL-P-85891A&#8221; on a data sheet mean the same thing as &#8220;certified to MIL-P-85891A&#8221; on a CoC?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">No \u2014 these phrases have meaningfully different implications. &#8220;Meets MIL-P-85891A&#8221; on a product data sheet is a manufacturer&#8217;s claim that their product is formulated and manufactured to comply with the specification&#8217;s requirements. It is a marketing claim that has not necessarily been verified by independent testing of a specific lot. &#8220;Certified to MIL-P-85891A&#8221; on a Certificate of Conformance, when backed by actual measured lot test results, is a quality record asserting that a specific, identified lot of media was tested and found to meet the specification requirements. The data sheet claim matters for initial supplier qualification \u2014 it tells you the manufacturer intends their product to meet the spec. The CoC with measured values is what matters for quality system compliance \u2014 it provides evidence that the actual lot you received was tested and met the requirements. For regulated applications, the data sheet claim is not sufficient; you need the lot-specific CoC with measured values every time you receive a shipment.<\/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\">Our process specification says &#8220;plastic blast media&#8221; without specifically citing MIL-P-85891A. Do we still need MIL-spec media?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">If your process specification does not cite MIL-P-85891A by document number, you technically do not have a contractual requirement for MIL-spec media \u2014 only a requirement for &#8220;plastic blast media&#8221; meeting whatever performance requirements your process document states. However, before sourcing commercial-grade media, check three things. First, does your process specification specify any measurable properties for the media \u2014 particle size distribution, moisture content, hardness? If so, ensure your commercial-grade supplier can document that their product meets those specific requirements, even if under a commercial specification rather than the military one. Second, does your quality system require documented material traceability with lot-level CoC for all materials used in regulated processes? If yes, the CoC format requirements from MIL-P-85891A are a useful template for what your commercial CoC must contain, even if the document itself is not required. Third, does your customer&#8217;s higher-level document (the aircraft OEM&#8217;s maintenance manual, for example) reference MIL-P-85891A even if your process specification does not? If the OEM&#8217;s document requires MIL-spec media, your process specification&#8217;s silence on the point does not supersede the OEM&#8217;s requirement \u2014 you still need to comply with the higher-level governing document.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">What is the difference between MIL-P-85891A Type II Class 1 and Type II Class 2? Which should I order?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Class 1 and Class 2 differ in particle shape: Class 1 is angular and irregular (the standard blast media shape that produces cutting action on coatings), while Class 2 is spherical or rounded (which produces a peening rather than cutting action). For essentially all coating removal, surface preparation, mold cleaning, and deflashing applications \u2014 which represents the overwhelming majority of plastic blast media use \u2014 you want Class 1. Class 2 is specified for a narrow set of applications where a rounded particle is needed for a very controlled peening effect without the angular cutting action. In practice, most purchasers ordering for coating removal never encounter Class 2; if your process specification says only &#8220;Type II&#8221; without specifying Class, assume Class 1 and confirm with the process engineer if uncertain. Class 1 is also far more commonly stocked by suppliers \u2014 Class 2 may require special order with longer lead times and potentially higher minimum quantities.<\/p>\n    <\/div>\n  <\/div>\n\n  <div class=\"pm-faq-item\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n    <p class=\"pm-faq-q\" itemprop=\"name\">Can I use MIL-P-85891A media for non-aerospace applications, and is there any reason not to?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">Yes, MIL-P-85891A media can be used for any application where plastic blast media is appropriate \u2014 aerospace, automotive, mold cleaning, electronics, or industrial. There is no restriction on using MIL-spec media for non-aerospace applications; the specification defines minimum quality standards, and those standards produce good media regardless of the application context. The only reason not to specify MIL-P-85891A for non-aerospace applications is cost: the testing, documentation, and quality system overhead required to produce genuinely compliant MIL-spec media adds 15\u201330% to the per-pound price compared to equivalent commercial-grade media. If your application does not require lot-level documentation, pH testing, or any of the other MIL-spec requirements, you are paying for documentation you will never use. For high-volume commercial operations where the primary goal is blast performance rather than quality records, well-characterized commercial-grade media from a supplier with good lot-to-lot consistency may be the economically rational choice. For applications where you need the documentation \u2014 AS9100 quality systems, regulated aerospace work, any situation where material traceability is auditable \u2014 the premium for MIL-spec media is justified and well worth paying.<\/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\">A supplier says they are &#8220;qualified&#8221; to MIL-P-85891A. What does that mean, and how do I verify it?<\/p>\n    <div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n      <p class=\"pm-faq-a\" itemprop=\"text\">When a supplier says they are &#8220;qualified&#8221; to MIL-P-85891A, they may mean one of three things with very different implications. First, they may mean they are listed on the Qualified Products List (QPL-85891) \u2014 their product has been submitted for formal DoD qualification testing by an independent laboratory, passed all requirements, and their product designation appears in the QPL maintained by DLA. This is the strongest form of qualification and is verifiable by checking the current QPL-85891 on the DLA ASSIST database. Second, they may mean their product has been internally validated to meet the specification&#8217;s technical requirements and they produce lot-level CoC documentation accordingly \u2014 they are &#8220;self-certified&#8221; to the standard rather than formally QPL-listed. This is meaningful and appropriate for many commercial applications, but is not the same as QPL listing for contract purposes. Third, they may mean simply that they are familiar with the specification and believe their product meets it \u2014 the weakest claim, which requires you to verify through CoC examination. To determine which meaning applies, ask specifically: &#8220;Is your product listed on the current DoD QPL-85891?&#8221; If yes, request their QPL product designation and verify it on DLA ASSIST. If no, ask for a sample CoC with actual measured lot test values to assess whether their documentation meets the specification&#8217;s evidence requirements.<\/p>\n    <\/div>\n  <\/div>\n\n<\/div>\n\n<hr class=\"pm-section-divider\">","protected":false},"excerpt":{"rendered":"<p>Mil-Spec Plastic Media: What MIL-P-85891A Means for Buyers MIL-P-85891A is  [&#8230;]<\/p>","protected":false},"author":1,"featured_media":12367,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,177,138],"tags":[],"class_list":["post-12360","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\/12360","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=12360"}],"version-history":[{"count":3,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/12360\/revisions"}],"predecessor-version":[{"id":12386,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/posts\/12360\/revisions\/12386"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/media\/12367"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/media?parent=12360"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/categories?post=12360"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/es\/wp-json\/wp\/v2\/tags?post=12360"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}