{"id":9174,"date":"2024-01-08T01:00:00","date_gmt":"2024-01-08T01:00:00","guid":{"rendered":"https:\/\/uplastech.com\/antistat-coating-decay-stored-trays\/"},"modified":"2026-11-08T08:10:47","modified_gmt":"2026-11-08T08:10:47","slug":"antistat-coating-decay-stored-trays","status":"publish","type":"post","link":"https:\/\/uplastech.com\/it\/antistat-coating-decay-stored-trays\/","title":{"rendered":"Antistat Coating That Fades in Store: Qualifying Surface Resistivity After 90 Days"},"content":{"rendered":"<style>\n.upl-blog{font-size:17px;line-height:1.78;color:#1f2937}\n.upl-blog p{margin:0 0 18px}\n.upl-blog h2{font-size:26px;line-height:1.3;color:#0b2b33;margin:46px 0 14px;font-weight:700;letter-spacing:-.015em}\n.upl-blog h3{font-size:19.5px;color:#0d3b47;margin:28px 0 10px;font-weight:700}\n.upl-blog ul,.upl-blog ol{margin:0 0 20px;padding-left:22px}\n.upl-blog li{margin:0 0 9px}\n.upl-blog figure{margin:0 0 34px}\n.upl-blog figure 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ul.cta-need li{color:#e4f0f2;font-size:14.5px;padding-left:18px;position:relative;margin:0}\n.upl-blog ul.cta-need li::before{content:\"\\2713\";position:absolute;left:0;color:#e07a1f;font-weight:700}\n\/* ==UPL-CONVERSION-MODULES-END== *\/\n@media(max-width:640px){.upl-blog h2{font-size:22px}.upl-blog table{font-size:13px}.upl-blog .cta{padding:24px}.upl-blog ul.conv-need,.upl-blog ul.cta-need{grid-template-columns:1fr}.upl-blog .problem,.upl-blog .steps,.upl-blog .conv,.upl-blog .checklist{padding:18px}}\n\/* \u5355\u7bc7\u9875\u9690\u85cf WhatsApp \u95ee\u5019\u5361\uff0c\u53ea\u4fdd\u7559\u5706\u5f62\u6c14\u6ce1\uff0c\u907f\u514d\u906e\u6321\u4fa7\u680f\u8be2\u76d8\u63d0\u4ea4\u6309\u94ae\u3002\n   \u6ce8\u610f\uff1aClick to Chat \u7684\u70b9\u51fb\u903b\u8f91\u662f\u300c\u95ee\u5019\u5361\u5143\u7d20\u5b58\u5728\u5c31\u4e0d\u8df3\u8f6c\u300d\uff0c\u53ea\u9760 CSS \u9690\u85cf\u4f1a\u8ba9\u6c14\u6ce1\u53d8\u6210\u6b7b\u94fe\u63a5\u3002\n   Code Snippets #9\u300cUPL single post: WhatsApp bubble jumps straight to chat\u300d\u8d1f\u8d23\u628a\u8be5\u8282\u70b9\u4ece DOM \u79fb\u9664\uff0c\n   \u4e0b\u9762\u8fd9\u6761 CSS \u53ea\u662f\u79fb\u9664\u524d\u7684\u89c6\u89c9\u515c\u5e95\u3002\u5220 #9 \u524d\u5fc5\u987b\u5148\u5220\u8fd9\u6761\u89c4\u5219\u3002 *\/\nbody.single-post .ht_ctc_chat_greetings_box{display:none !important}\n<\/style>\n<div class=\"upl-blog\">\n<figure>\n<img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/11\/2024-antistat-coating-decay-stored-trays-hero.jpg\" alt=\"Real thermoformed plastic tray and packaging components\" width=\"1536\" height=\"909\"><figcaption>Real thermoforming production context. Photo: Pexels.<\/figcaption><\/figure>\n<div class=\"problem\">\n<p class=\"mod-h\">The problem<\/p>\n<p><b>Symptom.<\/b> ESD-sensitive trays pass surface resistivity at goods-in but fail the same test 90 days later, because a topical antistat coating has migrated or been wiped away during storage.<\/p>\n<p><b>What it costs.<\/b> A line-side ESD audit then rejects a full pallet of 20 000 trays that cannot be reworked, and the buyer disputes who owns a coating that met specification on delivery.<\/p>\n<p class=\"problem-promise\">This guide shows how to measure resistivity decay, distinguish a topical coating from an internal additive, and write a 90-day ESD clause into the purchase order.<\/p>\n<\/div>\n<div class=\"toc\"><\/div>\n<h2 id=\"the-failure-is-a-coating-durability-dispute-not-an-esd-programme-fault\">The failure is a coating-durability dispute, not an ESD-programme fault<\/h2>\n<p>A topical antistat is a thin, hygroscopic layer that can be rubbed off or absorbed into the sheet. A PET tray reading 10^9 ohm\/sq at goods-in can climb past 10^12 ohm\/sq after 90 days.<\/p>\n<table>\n<thead>\n<tr>\n<th>What the audit finds<\/th>\n<th>What is physically happening<\/th>\n<th>First measurement<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Pass at receipt, fail at 90 days<\/td>\n<td>Topical coating migrated or was rubbed away<\/td>\n<td>Resistivity at receipt and after 90 days at 25 \u00b0C<\/td>\n<\/tr>\n<tr>\n<td>Fail only in dry winter months<\/td>\n<td>Hygroscopic coat starved of moisture at 20 % RH<\/td>\n<td>Resistivity at 20 % and 50 % RH<\/td>\n<\/tr>\n<tr>\n<td>Some trays pass, some fail<\/td>\n<td>Uneven coating or a wipedown on one layer<\/td>\n<td>Five-point probe map across the tray surface<\/td>\n<\/tr>\n<tr>\n<td>Both topical and internal lots drift<\/td>\n<td>Storage at 30 \u00b0C exceeds the qualified window<\/td>\n<td>Logged warehouse temperature and RH<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 - Classifying an ESD failure before changing suppliers<\/p>\n<div class=\"callout\">Record which of these you are actually seeing before changing any setting. Two faults can look identical on the line and need opposite corrections.<\/div>\n<p><!-- upl-conv-v1 quickcta --><\/p>\n<div class=\"quickcta\">\n<p class=\"mod-h\">Need a fixed price for this formed tray?<\/p>\n<p>Send the tray drawing, sheet gauge and annual volume. We will review draft, trim and material, then quote a production tool with a written line-acceptance test.<\/p>\n<p class=\"quickcta-act\"><a class=\"quickcta-btn\" href=\"https:\/\/uplastech.com\/vacuum-forming\/\">Get a thermoforming quotation<\/a><a class=\"quickcta-alt\" href=\"mailto:john@uplastech.com\">Email john@uplastech.com<\/a><a class=\"quickcta-alt\" href=\"https:\/\/wa.me\/8617717529949\">WhatsApp<\/a><\/p>\n<\/div>\n<h2 id=\"measure-surface-resistivity-at-receipt-and-after-conditioning\">Measure surface resistivity at receipt and after conditioning<\/h2>\n<p>Measure with a concentric-ring probe per IEC 61340-2-3 at 23 \u00b0C and 50 % RH, five points per tray. One audit logged 8 x 10^8 at receipt and 3 x 10^12 after 90 days at 30 \u00b0C.<\/p>\n<div class=\"steps\">\n<p class=\"mod-h\">A five-step diagnostic sequence<\/p>\n<ol>\n<li><b>Condition the sample.<\/b><br \/>Hold trays at 23 \u00b0C and 50 % RH for 24 h before any measurement.<\/li>\n<li><b>Map five points.<\/b><br \/>Use a concentric-ring probe per IEC 61340-2-3 at five sites per tray.<\/li>\n<li><b>Record at receipt.<\/b><br \/>Log resistivity on 20 trays from three lots within 48 h of delivery.<\/li>\n<li><b>Store and re-test.<\/b><br \/>Repeat at 30, 60 and 90 days at the declared storage conditions.<\/li>\n<li><b>Stress one variable.<\/b><br \/>Re-test a subset at 20 % RH to expose a moisture-dependent coating.<\/li>\n<\/ol>\n<\/div>\n<p>The chart below is a typical result from that measurement step. Use it to separate a design limit from a setting that can still be recovered.<\/p>\n<figure>\n<img decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/11\/antistat-coating-decay-stored-trays-chart3.jpg\" alt=\"Antistat Coating That Fades in Store: Qualifying Surface Resistivity After 90 Days: calculated response trend and an illustrative root-cause split\" width=\"1536\" height=\"909\"><figcaption>Figure 1 \u2014 Calculated response trend and an illustrative root-cause split. Values are engineering guidance for diagnosis, not a measured survey; confirm them on your own line before changing a drawing or a specification.<\/figcaption><\/figure>\n<h2 id=\"coating-type-target-resistivity-and-storage-conditions-to-specify\">Coating type, target resistivity and storage conditions to specify<\/h2>\n<p>Three parameters belong in the specification: a 10^9-10^11 ohm\/sq band after conditioning, an internally dosed antistat, and storage at 25 \u00b0C and 60 % RH for 90 days. A topical coat cannot hold it.<\/p>\n<table class=\"spec\">\n<thead>\n<tr>\n<th>Parameter<\/th>\n<th>Typical target<\/th>\n<th>What goes wrong outside it<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Surface resistivity after 90 days<\/td>\n<td>10^9 - 10^11 ohm\/sq<\/td>\n<td>Higher values fail an ESD-protective packaging audit<\/td>\n<\/tr>\n<tr>\n<td>Antistat type<\/td>\n<td>Internally dosed, not topical<\/td>\n<td>Topical coats migrate or wipe off in storage<\/td>\n<\/tr>\n<tr>\n<td>Storage conditions<\/td>\n<td>25 \u00b0C, 60 % RH, 90 days<\/td>\n<td>Heat and low humidity accelerate resistivity drift<\/td>\n<\/tr>\n<tr>\n<td>Test method<\/td>\n<td>IEC 61340-2-3, five points<\/td>\n<td>Single-point readings hide an uneven coating<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 - ESD parameters to write on the tray specification<\/p>\n<h2 id=\"why-resistivity-climbs-after-a-humidity-or-packaging-change\">Why resistivity climbs after a humidity or packaging change<\/h2>\n<p>Resistivity climbs faster when storage shifts. A warehouse at 20 % RH starves a hygroscopic coat, a PE overwrap extracts the additive, and an isopropyl wipedown strips it outright.<\/p>\n<table>\n<thead>\n<tr>\n<th>Process variable<\/th>\n<th>Effect on the coating<\/th>\n<th>Practical control<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Storage RH at 20 %<\/td>\n<td>Hygroscopic coat loses its conductive layer<\/td>\n<td>Hold warehouse at 50 % RH or use an internal grade<\/td>\n<\/tr>\n<tr>\n<td>Warehouse at 30 \u00b0C<\/td>\n<td>Additive migrates faster into the sheet<\/td>\n<td>Cap storage at 25 \u00b0C and log temperature<\/td>\n<\/tr>\n<tr>\n<td>PE overwrap in contact<\/td>\n<td>Film extracts the antistat from the surface<\/td>\n<td>Specify a non-extractive wrap or a barrier layer<\/td>\n<\/tr>\n<tr>\n<td>Isopropyl wipedown<\/td>\n<td>Solvent strips a topical coat instantly<\/td>\n<td>Ban solvent cleaning in the handling instruction<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 3 - Variables that raise resistivity after sign-off<\/p>\n<div class=\"myth\"><b>Myth:<\/b> \"A process adjustment will fix it.\" Once a design limit is reached, more tuning only adds cost and variation. Confirm the limit with a measurement, then change the drawing or the specification.<\/div>\n<h2 id=\"a-90-day-esd-clause-for-the-purchase-order\">A 90-day ESD clause for the purchase order<\/h2>\n<p>A goods-in reading alone cannot settle the dispute. Add a clause: resistivity within 10^9-10^11 ohm\/sq after 90 days at 25 \u00b0C and 60 % RH, measured on 20 trays from three lots.<\/p>\n<div class=\"conv\">\n<p class=\"mod-h\">Want the tray checked against your line?<\/p>\n<p>Send us the tray drawing and the line conditions. We will flag the geometry and material choices that cause jams, and quote a tool with an acceptance test.<\/p>\n<p class=\"conv-lbl\">What to send us<\/p>\n<ul class=\"conv-need\">\n<li>Tray drawing with draft and radii<\/li>\n<li>Sheet grade and gauge<\/li>\n<li>Stack depth and line speed<\/li>\n<li>Drawings of the magazine or denester<\/li>\n<\/ul>\n<p><a class=\"conv-btn\" href=\"\/vacuum-forming\/\">Send the tray drawing<\/a>\n<\/div>\n<h2 id=\"costing-an-internal-antistat-against-a-disputed-pallet\">Costing an internal antistat against a disputed pallet<\/h2>\n<p>An internally dosed masterbatch adds roughly 4-7 p per tray but holds the band for the full shelf life. One quarantined 20 000-tray pallet costs more than that premium across the whole order.<\/p>\n<div class=\"callout\">Validate one change at a time and keep the measurement record. A supplier discussion backed by data is resolved in days, not weeks.<\/div>\n<div class=\"checklist\">\n<p class=\"mod-h\">Before you sign off this thermoformed tool<\/p>\n<ul>\n<li>A resistivity band is stated after 90 days of conditioning, not only at goods-in<\/li>\n<li>The antistat is named as internally dosed or topical on the material specification<\/li>\n<li>Storage temperature, RH and duration are defined on the purchase order<\/li>\n<li>The test method and five-point probe map are written into the acceptance clause<\/li>\n<li>Resistivity is re-tested at 30, 60 and 90 days across three production lots<\/li>\n<\/ul>\n<p class=\"cl-note\">A tray that looks right in the carton can still stop a filling line. Test the stack, not a single part.<\/p>\n<\/div>\n<div class=\"faq\">\n<h3>Why did the trays pass at goods-in and fail later?<\/h3>\n<p>A topical antistat is a surface layer, and its resistivity depends on moisture and physical integrity. It can read perfectly on day one, then migrate, be wiped or dry out over 90 days. Only a time-qualified test catches that.<\/p>\n<h3>Is a higher initial resistivity always a bad batch?<\/h3>\n<p>Not necessarily. Measure at a controlled 23 \u00b0C and 50 % RH first, since a dry reading can be an order of magnitude high. If it stays high after conditioning, the coating or the dose is at fault.<\/p>\n<h3>Does an internal antistat cost much more?<\/h3>\n<p>Typically 4-7 p per tray in masterbatch. Set against one quarantined 20 000-tray pallet and a disputed order, it is usually the cheaper specification, and it removes the durability argument entirely.<\/p>\n<h3>Can we just re-apply an antistat coating?<\/h3>\n<p>A re-applied topical coat resets the clock but is uneven, easily wiped and hard to qualify. For ESD-protective packaging, an internally dosed grade with a 90-day clause is more defensible in an audit.<\/p>\n<h3>What role does humidity play?<\/h3>\n<p>Topical antistats are hygroscopic, so at 20 % RH they lose the moisture layer that conducts charge and resistivity can jump by two or three decades. Control RH or specify a humidity-independent internal grade.<\/p>\n<h3>What should the ESD clause say?<\/h3>\n<p>Resistivity within 10^9-10^11 ohm\/sq after 90 days at 25 \u00b0C and 60 % RH, measured by IEC 61340-2-3 at five points on 20 trays from three lots, with 30 and 60 day interim records.<\/p>\n<\/div>\n<div class=\"cta\">\n<p class=\"cta-h\">Get a tray that runs on your filling line<\/p>\n<p>Send us the tray drawing or a sample stack. We will review draft, trim and material, then quote a production tool with a measurable line-acceptance test written into it.<\/p>\n<p class=\"cta-lbl\">To get an accurate quote, send:<\/p>\n<ul class=\"cta-need\">\n<li>Tray drawing or sample stack<\/li>\n<li>Sheet material and gauge<\/li>\n<li>Line speed and denesting method<\/li>\n<li>Annual volume and target unit price<\/li>\n<\/ul>\n<p><a class=\"btn\" href=\"\/vacuum-forming\/\">Request a tool and tray quotation<\/a><br \/>\n<!-- upl-conv-v1 contact --><\/p>\n<div class=\"contactbar\">\n<p class=\"contactbar-h\">Prefer to talk it through first?<\/p>\n<p>Email <a href=\"mailto:john@uplastech.com\">john@uplastech.com<\/a> or message us on <a href=\"https:\/\/wa.me\/8617717529949\">WhatsApp +86 177 1752 9949<\/a>. Send a drawing, a sample or a specification and an engineer will reply.<\/p>\n<\/div>\n<p><!-- upl-conv-v1 trust --><\/p>\n<div class=\"trust\">\n<p class=\"trust-h\">Why buyers work with Uplastech<\/p>\n<p>ISO 9001, ISO 14001 and ISO 45001 certified. Founded in 2016, with injection moulding lines in Shanghai and an extrusion plant in Jiangsu. Moulding machines from 90T to 1100T and a maximum shot weight of 5100 g. Samples and a written quotation are available on request.<\/p>\n<\/div>\n<\/div>\n<div class=\"rel\">\n<h4>Continue reading<\/h4>\n<ul>\n<li><a href=\"https:\/\/uplastech.com\/thermoforming-sheet-thickness-tolerance\/\">Thermoforming sheet thickness tolerance<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/thermoforming-stacking-nesting\/\">Thermoforming stacking and nesting<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/thermoforming-tolerances\/\">Thermoforming tolerances<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/thermoforming-trimming-methods\/\">Thermoforming trimming methods<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/effects-of-manufacturing-defects-on-thermoformed-packaging-quality\/\">Manufacturing defects in thermoformed packaging<\/a><\/li>\n<\/ul>\n<p><!-- upl-conv-v1 service --><\/p>\n<p class=\"rel-svc\">Ready to specify? See our <a href=\"https:\/\/uplastech.com\/vacuum-forming\/\">vacuum forming and thermoforming services<\/a> or <a href=\"mailto:john@uplastech.com\">request a written quotation<\/a>.<\/p>\n<\/div>\n<\/div>\n<p><script type=\"application\/ld+json\">{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Why did the trays pass at goods-in and fail later?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"A topical antistat is a surface layer, and its resistivity depends on moisture and physical integrity. It can read perfectly on day one, then migrate, be wiped or dry out over 90 days. Only a time-qualified test catches that.\"}}, {\"@type\": \"Question\", \"name\": \"Is a higher initial resistivity always a bad batch?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Not necessarily. Measure at a controlled 23 \u00b0C and 50 % RH first, since a dry reading can be an order of magnitude high. If it stays high after conditioning, the coating or the dose is at fault.\"}}, {\"@type\": \"Question\", \"name\": \"Does an internal antistat cost much more?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Typically 4-7 p per tray in masterbatch. Set against one quarantined 20 000-tray pallet and a disputed order, it is usually the cheaper specification, and it removes the durability argument entirely.\"}}, {\"@type\": \"Question\", \"name\": \"Can we just re-apply an antistat coating?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"A re-applied topical coat resets the clock but is uneven, easily wiped and hard to qualify. For ESD-protective packaging, an internally dosed grade with a 90-day clause is more defensible in an audit.\"}}, {\"@type\": \"Question\", \"name\": \"What role does humidity play?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Topical antistats are hygroscopic, so at 20 % RH they lose the moisture layer that conducts charge and resistivity can jump by two or three decades. Control RH or specify a humidity-independent internal grade.\"}}, {\"@type\": \"Question\", \"name\": \"What should the ESD clause say?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Resistivity within 10^9-10^11 ohm\/sq after 90 days at 25 \u00b0C and 60 % RH, measured by IEC 61340-2-3 at five points on 20 trays from three lots, with 30 and 60 day interim records.\"}}]}<\/script><\/p>\n","protected":false},"excerpt":{"rendered":"<p>This guide shows how to measure resistivity decay, distinguish a topical coating from an internal additive, and write a 90-day ESD clause into the purchase order.<\/p>","protected":false},"author":1,"featured_media":9172,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29],"tags":[],"class_list":["post-9174","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-vacuum-forming"],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/posts\/9174","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/comments?post=9174"}],"version-history":[{"count":1,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/posts\/9174\/revisions"}],"predecessor-version":[{"id":9271,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/posts\/9174\/revisions\/9271"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/media\/9172"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/media?parent=9174"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/categories?post=9174"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/tags?post=9174"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}