{"id":9338,"date":"2024-01-15T01:00:00","date_gmt":"2024-01-15T01:00:00","guid":{"rendered":"https:\/\/uplastech.com\/pet-sheet-regrind-clarity-haze-limit\/"},"modified":"2026-11-08T08:12:09","modified_gmt":"2026-11-08T08:12:09","slug":"pet-sheet-regrind-clarity-haze-limit","status":"publish","type":"post","link":"https:\/\/uplastech.com\/ar\/pet-sheet-regrind-clarity-haze-limit\/","title":{"rendered":"PET Sheet Regrind and Haze: Setting a Clarity Ceiling on the Sheet Order"},"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-pet-sheet-regrind-clarity-haze-limit-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> A retail packer rejects clear APET trays because a new sheet lot reads 7.8 % haze instead of the usual 2.1 %, and the printed label shows a grey cast under the goods-in light booth.<\/p>\n<p><b>What it costs.<\/b> A 60 000-tray order is quarantined for a clarity the sheet certificate never mentioned, and the converter and sheet supplier argue over how much regrind the lot actually contained.<\/p>\n<p class=\"problem-promise\">This guide shows how to measure haze against regrind level, set a ceiling, and write a regrind cap and haze limit into the sheet purchase order.<\/p>\n<\/div>\n<div class=\"toc\"><\/div>\n<h2 id=\"haze-is-a-regrind-fault-not-a-forming-temperature-fault\">Haze is a regrind fault, not a forming-temperature fault<\/h2>\n<p>Regrind carries degraded polymer, gels and black specks that scatter light. On 0.6 mm APET, haze by ASTM D1003 rises from 2.1 % at 0 % regrind to 3.4 % at 15 %, 5.2 % at 30 % and 7.8 % at 40 %.<\/p>\n<table>\n<thead>\n<tr>\n<th>What goods-in sees<\/th>\n<th>What is physically happening<\/th>\n<th>First measurement<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>A grey cast behind the label<\/td>\n<td>Gels and specks scatter light through the base<\/td>\n<td>Haze by ASTM D1003 on flat sheet<\/td>\n<\/tr>\n<tr>\n<td>Only some trays look cloudy<\/td>\n<td>Regrind unevenly blended across the lot<\/td>\n<td>Haze at five points across the sheet width<\/td>\n<\/tr>\n<tr>\n<td>Good one lot, bad the next<\/td>\n<td>Regrind percentage changed without notice<\/td>\n<td>Regrind content declared on the lot certificate<\/td>\n<\/tr>\n<tr>\n<td>Yellowing after storage<\/td>\n<td>Regrind degraded by heat or daylight<\/td>\n<td>IV and colour of the incoming regrind<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 - Classifying a clarity fault before changing the former<\/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-haze-at-four-regrind-levels-before-changing-the-oven\">Measure haze at four regrind levels before changing the oven<\/h2>\n<p>Read haze on a flat sheet sample with a hazemeter, then section a formed tray. Interpolating between 15 % and 30 % regrind, a 4.0 % haze ceiling corresponds to 3.4 + 5\/15 \u00d7 1.8 = 4.0 % at 20 % regrind.<\/p>\n<div class=\"steps\">\n<p class=\"mod-h\">A five-step diagnostic sequence<\/p>\n<ol>\n<li><b>Sample the sheet.<\/b><br \/>Take flat sheet from the start, middle and end of the incoming reel.<\/li>\n<li><b>Measure haze.<\/b><br \/>Read ASTM D1003 haze at five points across the width with a hazemeter.<\/li>\n<li><b>Check the regrind.<\/b><br \/>Record regrind percentage and IV from the lot certificate.<\/li>\n<li><b>Form and compare.<\/b><br \/>Thermoform 30 trays and inspect the label zone under D65 light.<\/li>\n<li><b>Qualify three lots.<\/b><br \/>Repeat across three sheet lots and attach the haze record to first-off.<\/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\/pet-sheet-regrind-clarity-haze-limit-chart.jpg\" alt=\"PET Sheet Regrind and Haze: Setting a Clarity Ceiling on the Sheet Order: 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=\"regrind-percentage-iv-and-melt-filtration-to-specify\">Regrind percentage, IV and melt filtration to specify<\/h2>\n<p>Three numbers protect clarity: a haze ceiling of 4.0 % by ASTM D1003, a regrind cap of 20 %, and regrind IV held above 0.70 dL\/g with 40 \u00b5m melt filtration. A 40 % lot at 7.8 % haze fails all three.<\/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>Haze, ASTM D1003, 0.6 mm sheet<\/td>\n<td>\u2264 4.0 %<\/td>\n<td>A 7.8 % lot greys the label zone<\/td>\n<\/tr>\n<tr>\n<td>Regrind in the sheet<\/td>\n<td>\u2264 20 %<\/td>\n<td>40 % regrind reads 7.8 % haze<\/td>\n<\/tr>\n<tr>\n<td>Regrind intrinsic viscosity<\/td>\n<td>\u2265 0.70 dL\/g<\/td>\n<td>Degraded regrind scatters light and yellows<\/td>\n<\/tr>\n<tr>\n<td>Melt filtration<\/td>\n<td>40 \u00b5m screen<\/td>\n<td>A 60 \u00b5m screen lets gels through<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 - Clarity parameters to write on the sheet purchase order<\/p>\n<h2 id=\"variables-that-raise-haze-after-a-lot-or-dryer-change\">Variables that raise haze after a lot or dryer change<\/h2>\n<p>Haze climbs again as the lot is handled. A dryer running 10 \u00b0C hot degrades regrind further, a 60 \u00b5m screen lets gels through, and a regrind drum stored in daylight adds yellowing that the hazemeter catches as scattered light.<\/p>\n<table>\n<thead>\n<tr>\n<th>Process variable<\/th>\n<th>Effect on haze<\/th>\n<th>Practical control<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Regrind raised from 20 % to 40 %<\/td>\n<td>Haze climbs from 4.0 % to 7.8 %<\/td>\n<td>Cap regrind at 20 % on the sheet order<\/td>\n<\/tr>\n<tr>\n<td>Dryer 10 \u00b0C too hot<\/td>\n<td>Regrind degrades and yellows<\/td>\n<td>Log dryer temperature per shift<\/td>\n<\/tr>\n<tr>\n<td>Screen changed to 60 \u00b5m<\/td>\n<td>Gels pass into the sheet<\/td>\n<td>Hold 40 \u00b5m melt filtration<\/td>\n<\/tr>\n<tr>\n<td>Regrind IV below 0.70 dL\/g<\/td>\n<td>Degraded polymer scatters more light<\/td>\n<td>Require an IV value per regrind lot<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 3 - Variables that raise haze 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-haze-ceiling-and-regrind-cap-for-the-sheet-order\">A haze ceiling and regrind cap for the sheet order<\/h2>\n<p>A clarity complaint needs a number, not an opinion. Add a clause: haze \u2264 4.0 % by ASTM D1003 on 0.6 mm sheet, regrind \u2264 20 %, verified on 30 trays from three sheet lots under D65 light.<\/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-a-capped-regrind-against-a-quarantined-tray-order\">Costing a capped regrind against a quarantined tray order<\/h2>\n<p>Capping regrind at 20 % and specifying 40 \u00b5m filtration add roughly 2-3 p per tray but remove the 7.8 % haze lot. One quarantined 60 000-tray order costs more than the resin premium across the whole contract.<\/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 haze ceiling \u2264 4.0 % by ASTM D1003 is stated on the sheet order<\/li>\n<li>A regrind cap of 20 % is written into the material specification<\/li>\n<li>Regrind IV \u2265 0.70 dL\/g and 40 \u00b5m melt filtration are specified<\/li>\n<li>Haze is measured on flat sheet and on formed trays under D65 light<\/li>\n<li>The clarity test covers three sheet lots, not a single first-off reel<\/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 clarity change with a new sheet lot?<\/h3>\n<p>Regrind level is the usual cause. On 0.6 mm APET haze rises from 2.1 % at 0 % regrind to 7.8 % at 40 %. A lot blended to 40 % without notice will grey the label zone even if gauge is correct.<\/p>\n<h3>Where does the 20 % cap come from?<\/h3>\n<p>It is the regrind level where a 4.0 % haze ceiling is met. Interpolating the measured 3.4 % at 15 % and 5.2 % at 30 % gives 3.4 + 5\/15 \u00d7 1.8 = 4.0 % at 20 % regrind.<\/p>\n<h3>Can a hotter oven clear the haze?<\/h3>\n<p>No. Haze is scattered light from gels and degraded polymer in the sheet, not a forming mark. More heat can yellow the PET further. Cap the regrind and specify melt filtration instead.<\/p>\n<h3>Is melt filtration worth specifying?<\/h3>\n<p>Yes. A 40 \u00b5m screen holds back the gels that a 60 \u00b5m screen passes, and pairs with the regrind cap. It is cheaper than quarantining a 60 000-tray order for a grey cast.<\/p>\n<h3>Does regrind IV matter?<\/h3>\n<p>It tracks degradation. Below 0.70 dL\/g the polymer has been heat-worked, scatters more light and yellows. Ask for an IV value on every regrind lot and re-qualify haze when it drops.<\/p>\n<h3>What should the clarity clause say?<\/h3>\n<p>Haze \u2264 4.0 % by ASTM D1003 on 0.6 mm sheet, regrind \u2264 20 %, IV \u2265 0.70 dL\/g and 40 \u00b5m filtration, verified on 30 trays from three sheet lots under D65 light.<\/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 clarity change with a new sheet lot?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Regrind level is the usual cause. On 0.6 mm APET haze rises from 2.1 % at 0 % regrind to 7.8 % at 40 %. A lot blended to 40 % without notice will grey the label zone even if gauge is correct.\"}}, {\"@type\": \"Question\", \"name\": \"Where does the 20 % cap come from?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"It is the regrind level where a 4.0 % haze ceiling is met. Interpolating the measured 3.4 % at 15 % and 5.2 % at 30 % gives 3.4 + 5\/15 \u00d7 1.8 = 4.0 % at 20 % regrind.\"}}, {\"@type\": \"Question\", \"name\": \"Can a hotter oven clear the haze?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"No. Haze is scattered light from gels and degraded polymer in the sheet, not a forming mark. More heat can yellow the PET further. Cap the regrind and specify melt filtration instead.\"}}, {\"@type\": \"Question\", \"name\": \"Is melt filtration worth specifying?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. A 40 \u00b5m screen holds back the gels that a 60 \u00b5m screen passes, and pairs with the regrind cap. It is cheaper than quarantining a 60 000-tray order for a grey cast.\"}}, {\"@type\": \"Question\", \"name\": \"Does regrind IV matter?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"It tracks degradation. Below 0.70 dL\/g the polymer has been heat-worked, scatters more light and yellows. Ask for an IV value on every regrind lot and re-qualify haze when it drops.\"}}, {\"@type\": \"Question\", \"name\": \"What should the clarity clause say?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Haze \u2264 4.0 % by ASTM D1003 on 0.6 mm sheet, regrind \u2264 20 %, IV \u2265 0.70 dL\/g and 40 \u00b5m filtration, verified on 30 trays from three sheet lots under D65 light.\"}}]}<\/script><\/p>\n","protected":false},"excerpt":{"rendered":"<p>This guide shows how to measure haze against regrind level, set a ceiling, and write a regrind cap and haze limit into the sheet purchase order.<\/p>","protected":false},"author":1,"featured_media":9336,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29],"tags":[],"class_list":["post-9338","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\/ar\/wp-json\/wp\/v2\/posts\/9338","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/comments?post=9338"}],"version-history":[{"count":1,"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/posts\/9338\/revisions"}],"predecessor-version":[{"id":9919,"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/posts\/9338\/revisions\/9919"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/media\/9336"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/media?parent=9338"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/categories?post=9338"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/ar\/wp-json\/wp\/v2\/tags?post=9338"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}