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In plastic injection molding, buildup can cause a multitude of defects, including gloss. Whether duller or shinier than the spec, all over or only on certain areas of the molded part, gloss can cause rejects or scraps, which you’ll want to mitigate.

How to Identify Gloss from Buildup

As you probably know, buildup isn’t the only cause of gloss. Lack of venting, converging material flow, and certain materials, especially cheaper grades, can also lead to gloss issues. For the sake of this blog post, we’re focusing specifically on gloss caused by buildup.

Easy to identify, gloss from buildup typically presents as a type of discoloration. If this looks and sounds like what you’re experiencing, there are two things you can do to get back in line with the gloss spec: use a coating and/or give the mold a cleaning.

Using a Coating

The right plastic injection mold coating can help minimize buildup and improve mold cleaning, which in turn resolves any related gloss issues. Nanoplas carries a variety of coatings. Choose your coating based on the material being molded and preferred application, i.e. in the press on a hot mold or in the tool room at room temperature.

In the Press Injection Mold Coatings

  • Nanoplas QC™ Quick Cure is designed for all plastics, including thermoplastics, commodity grades, and engineering grades. It leaves a semi-permanent barrier on the surface using nanotechnology, won’t alter final part dimensions, and cures on a hot mold in 10-15 minutes.
  • Nanoplas QCru™ Quick Cure Rubber Formula features all the core benefits of our traditional Quick Cure, but is formulated specifically for rubber parts.
  • Nanoplas QCSI™ Quick Cure Silicone Formula was created for silicone parts, and has all the great properties that are in our base Quick Cure.

Tool Room Injection Mold Coatings

  • Nanoplas HC™ Heat Cure is made with nanotechnology and creates a semi-permanent barrier on the surface of the mold without impacting part dimension. It offers extraordinary plastic or rubber part release and is the longest-lasting of all Nanoplas coatings.
  • Nanoplas HCF Heat Cure FDA Compliant offers the same benefits of HC Heat Cure while also being FDA compliant.

Contact us if you need help choosing a mold coating or to request a free sample. With all Nanoplas mold coatings, follow our proper application guide to achieve the best results.

Cleaning to Remove Buildup

If you’re going to use a coating, per our application instructions, you’ll want to give the mold a thorough cleaning first. To do this, we recommend Mold Brite or Power Clean. The goal is to remove all debris, oil, lubricants, and rust preventatives from the entire surface of the mold, including all the pores and crevices. If either of those two cleaners don’t get rid of everything or you have some stubborn buildup, then we recommend Zap-Ox™, which will also remove rust, oxidation, stains, and more.

If you need to clean a coated mold, use Nano Mold Cleaner. This product is formulated so that it doesn’t remove coatings, helping the mold maintain its performance.

While gloss from buildup can be problematic, with the right coating or cleaner it can also be rectified relatively easily, helping reduce scrap and minimize rejects.