--- title: How to Remove Black Specks from Clear & Colored Parts description: Asaclean Purging Expert Pete Studders explains why processors deal with black specks/streaks, and how purging compounds can help solve the issue. image: https://www.asaclean.com/hubfs/Blog%20Header-clear%20and%20colored%20parts.jpg --- [ Order Online ](https://asaclean.my.site.com/b2bstore) [ Free Sample ](https://offers.asaclean.com/free-sample) ## [ Asaclean Blog ](https://www.asaclean.com/blog) Browse by Topic " aerospace asaclean asaclean news Asaclean® benefits asahi kasei automotive Best Practices black specks blisters blow molding blown-film extrusion buyers caps and closures carbon contamination cast-film extrusion Chemical Purging Compounds clear applications Color Changeovers Company News compounding consumer products contamination Cost savings custom molders Customer Success Story decreasing scrap defects electronics Energy Efficiency EX Grade extruder cleaning Extrusion fillament glass filled Glitter Grade Selection HDPE High and Low Temp Changeovers hold a bubble Hot Runners Injection Molding Injection Molding Tips LDPE Lightweight automotive components LLDPE low residue maintenance Material Changeovers Mechanical Purging Compounds medical Melt Flow Index NPE 24 nylons on the fly packaging PCR PEEK Polypropylene Post Consumer Resins preventative preventative purging processing tips profile extrusion Purge Program purge programs Purge Training Purge Trial purging purging compounds purging concentrates purging procedures Purging Tips quality recycled resins residue issues scrap reduction Screw Pulls sheet extrusion shutdown and sealing start-up super engineering resins Sustainability Tech Day technical support training trials Troubleshooting Twin Screw twin screw extrusion two step purging U Grade ULTEM venting Viscosity webinars wire extrusion - 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[Twin Screw](https://www.asaclean.com/blog/topic/twin-screw) - [twin screw extrusion](https://www.asaclean.com/blog/topic/twin-screw-extrusion) - [two step purging](https://www.asaclean.com/blog/topic/two-step-purging) - [U Grade](https://www.asaclean.com/blog/topic/u-grade) - [ULTEM](https://www.asaclean.com/blog/topic/ultem) - [venting](https://www.asaclean.com/blog/topic/venting) - [Viscosity](https://www.asaclean.com/blog/topic/viscosity) - [webinars](https://www.asaclean.com/blog/topic/webinars) - [wire extrusion](https://www.asaclean.com/blog/topic/wire-extrusion) [ Subscribe ](https://www.asaclean.com/blog/how-to-remove-black-specks-from-clear-colored-parts#subscribe-modal) ### Suscribirse Troubleshooting / 4 min read / January 20, 2022 # How to Remove Black Specks from Clear & Colored Parts - [Facebook Share ](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fhow-to-remove-black-specks-from-clear-colored-parts) - [Twitter Tweet ](https://twitter.com/intent/tweet?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fhow-to-remove-black-specks-from-clear-colored-parts&text=How+to+Remove+Black+Specks+from+Clear+%26amp%3B+Colored+Parts) - [LinkedIn Share ](https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fhow-to-remove-black-specks-from-clear-colored-parts&title=How%20to%20Remove%20Black%20Specks%20from%20Clear%20%26amp%3B%20Colored%20Parts&summary=Asaclean+Purging+Expert+Pete+Studders+explains+why+processors+deal+with+black+specks%2Fstreaks%2C+and+how+purging+compounds+can+help+solve+the+issue.&source=) - [Pinterest Pin ](https://pinterest.com/pin/create/button/?url=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fhow-to-remove-black-specks-from-clear-colored-parts) - [Email Email ](mailto:?subject=How%20to%20Remove%20Black%20Specks%20from%20Clear%20%26amp%3B%20Colored%20Parts&body=https%3A%2F%2Fwww.asaclean.com%2Fblog%2Fhow-to-remove-black-specks-from-clear-colored-parts) ![How to Remove Black Specks from Clear & Colored Parts](https://www.asaclean.com/hs-fs/hubfs/Blog%20Header-clear%20and%20colored%20parts.jpg?width=640&height=500&name=Blog%20Header-clear%20and%20colored%20parts.jpg) [![various-types-of-cellphone-cases](https://www.asaclean.com/hs-fs/hubfs/assets/images/images/Process-Industry-Industry/consumer-products/various-types-of-cellphone-cases.jpg?width=255&name=various-types-of-cellphone-cases.jpg)](https://www.cwbrabender.com/en/food/products/extruder/twin-screw-extruder/conical-twin-screw-extruder/) Black specks and/or streaks are one of the most common processing defects faced by molders, extruders, and blow molders alike. They are different from black spots which are caused by burns on the parts themselves. Black specks or streak can cause a mountain of scrap and leave even the best processors of clear or colored parts scratching their head. Why is this happening? Where did they come from? How do we solve this issue quickly? The most common cause of black specks and streaks is material degradation within the plastics processing system itself. This can be due to excessive temperatures, excessive residence time or trouble pre-existing contamination on the screw or barrel. It's also commonly caused as a result of using a multi generation regrind, or a compound that has a additive subject to degradation (such as flame retardant or susceptible pigments). Then there is also the chance of a foreign contaminant finding its way into the hopper or feed system. As is always the case, prevention is the best measure. This includes carefully setting up the temperature profile to meet the needs of the resin or compound being processed. Make sure any additives are compatible within the primary resin. Minimize residence time of any material, especially regrind. Check for and redesign any known dead spots within the system. Use and maintain good housekeeping practices, make sure material is always kept covered when in storage or in process. Even when all the above measures are taken, and the processor is still faced with defect causing black specks or streaks, one of the best remedies is to use a specialized purging compound for maximum cleaning power. A glass filled grade will aggressively clean the screw and barrel by letting the machines power do the work. Effectively removing even, the most stubborn residue and contaminants. As an added benefit, if the problem is so severe that an overhaul and system inspection is needed, products such as [Asaclean EX Grade](https://www.asaclean.com/purging-products/mechanical-purging-compound/ex-grade-purging-compound/) have a special additive package that will greatly assist with the screw removal and cleaning of the screw and barrel. If the contaminant causing the defect is found in an area of low pressure or a dead spot, a chemical type purging compound is a likely solution. Working by the principles of increased temperature and time, these types of purging compounds are excellent at expansion and removal in the out of the way places where this type of defect causing contamination often builds up. Using a purging compound is a common and reliable step most processors will consider before other alternatives such as sending out tooling or components to a specialized cleaner or performing manual cleaning tear down. Both of which can incur considerable costs in terms of expense and machine downtime. Using a purging compound as described should be a high priority and always an up-front consideration when needed for effective removal of these defect causing black specks or streaks. If you would like additional information and some useful tips on maintaining machinery and best practice purging methods, [please contact your Asaclean Technical Sales Representative](https://offers.asaclean.com/free-consultation). **Learn about the importance of implementing proper purging procedures by downloading this free industry guide.** **** ** [![](https://no-cache.hubspot.com/cta/default/468726/interactive-161630774182.png) ](https://www.asaclean.com/hs/cta/wi/redirect?encryptedPayload=AVxigLIxH7F%2FU0VsX8tPupGrsoHJxZRAQJEYGlpSauHWocgdWmAR8RDt9lnmrqZvspXUWrNtHG9Qb%2F%2FBahcWs9rY7kGlygfjbLTRH9SqMM2C%2FXoEDtIiLSNwPGbi86YuSZM5rwfumwemeg3iIjO50xswu9GmFFu4YCVWf9L5Ns6l66hhCzQJ5kD%2BOvBhVPyWdRWz8pIuVGZ%2Bnt%2BsJi8SmubQr08krYvt9vix2yedwK8YlHCyD%2FfyHMJvHZxN&webInteractiveContentId=161630774182&portalId=468726) ** ** ** ![Yoko Tanaka](https://www.asaclean.com/hs-fs/hubfs/Yoko%20Tanaka%20Headshot%203-25-16.jpg?width=150&name=Yoko%20Tanaka%20Headshot%203-25-16.jpg) #### [ Yoko Tanaka ](https://www.asaclean.com/blog/author/yoko-tanaka) Yoko Tanaka is the Marketing Manager at Asaclean. She has been helping molders and extruders learn about Asaclean purging and how to improve their processes for the past eight years. - [Share On LinkedIn ](https://www.linkedin.com/in/yokotanaka/) ## Related Posts [![Purging for Extrusion: Screw & Barrel vs. Downstream](https://www.asaclean.com/hs-fs/hubfs/Blog%20Header-extrusions%20screw%20vs%20downstream.jpg?width=450&height=250&name=Blog%20Header-extrusions%20screw%20vs%20downstream.jpg) Purging for Extrusion: Screw & Barrel vs. Downstream Chemical... / 4 min read / February 01, 2022 ](https://www.asaclean.com/blog/purging-for-extrusion-screw-barrel-vs.-downstream) [![If You Are A Molder, Here's Something to Consider](https://www.asaclean.com/hs-fs/hubfs/AI-Generated%20Media/Images/a%20street%20sign%20that%20says%20good%20choice%20pointing%20in%20one%20direction%20and%20bad%20choice%20pointing%20in%20the%20other%20direction.jpeg?width=450&height=250&name=a%20street%20sign%20that%20says%20good%20choice%20pointing%20in%20one%20direction%20and%20bad%20choice%20pointing%20in%20the%20other%20direction.jpeg) If You Are A Molder, Here's Something to Consider Troubleshooting / 2 min read / December 11, 2018 ](https://www.asaclean.com/blog/if-you-are-a-molder-heres-something-to-consider) ## Comments Get Started ## Ready to start improving your efficiency and increasing your profitability? - [Request a Consultation](https://www.asaclean.com/blog/how-to-remove-black-specks-from-clear-colored-parts#) - [Contact Sales](https://www.asaclean.com/blog/how-to-remove-black-specks-from-clear-colored-parts#) ![](https://www.asaclean.com/hubfs/assets/images/icons/icon-layers.svg) #### Free Sample Request a free sample of Asaclean® Purging Compounds for your plant and start saving today. 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[See your savings](https://www.asaclean.com/cost-savings-calculator) [ Back to Top ](https://www.asaclean.com/blog/how-to-remove-black-specks-from-clear-colored-parts#top) ```json { "@context" : "https://schema.org", "@type" : "BlogPosting", "author" : { "@type" : "Person", "name" : "Yoko Tanaka", "url" : "https://www.asaclean.com/blog/author/yoko-tanaka" }, "dateModified" : "2022-03-22T23:37:10.146Z", "datePublished" : "2022-01-20T20:16:47.000Z", "headline" : "How to Remove Black Specks from Clear & Colored Parts", "image" : [ "https://www.asaclean.com/hubfs/Blog%20Header-clear%20and%20colored%20parts.jpg" ], "mainEntityOfPage" : { "@id" : "https://www.asaclean.com/blog/how-to-remove-black-specks-from-clear-colored-parts", "@type" : "WebPage" }, "publisher" : { "@type" : "Organization", "logo" : { "@type" : "ImageObject", "url" : "https://www.asaclean.com/hubfs/Asaclean%20Logo%20TM.jpg" }, "name" : "Asahi Kasei Plastics North America" } } ``` ```json { "@context" : "http://schema.org", "@type" : "Article", "articleBody" : "Black specks and/or streaks are one of the most common processing defects faced by molders, extruders, and blow molders alike. They are different from black spots which are caused by burns on the parts themselves. Black specks or streak can cause a mountain of scrap and leave even the best processors of clear or colored parts scratching their head. Why is this happening? Where did they come from? How do we solve this issue quickly? The most common cause of black specks and streaks is material degradation within the plastics processing system itself. This can be due to excessive temperatures, excessive residence time or trouble pre-existing contamination on the screw or barrel. It's also commonly caused as a result of using a multi generation regrind, or a compound that has a additive subject to degradation (such as flame retardant or susceptible pigments). Then there is also the chance of a foreign contaminant finding its way into the hopper or feed system.", "author" : { "@type" : "Person", "name" : "Yoko Tanaka" }, "datePublished" : "January 20, 2022", "headline" : "How to Remove Black Specks from Clear & Colored Parts", "image" : "https://468726.fs1.hubspotusercontent-na1.net/hubfs/468726/Blog%20Header-clear%20and%20colored%20parts.jpg", "name" : "How to Remove Black Specks from Clear & Colored Parts", "url" : "https://www.asaclean.com/blog/how-to-remove-black-specks-from-clear-colored-parts" } ```