Primers/Sealers

Rub marks are typically a result of excess abrasion. Proper preparation of the tool and more frequent touch ups of release should minimize rub marks.

Many of the same factors that cause hazing also cause streaking. In our experience, streaking that occurs on application of release is most often the result of contamination, entrapped moisture, or improper application techniques. Presuming that the mold was cleaned properly, how you apply the release can have a big impact. Both sealer and release should be applied in a light even coating, using clean 100% cotton cloths. Do not use synthetic cloths because the solvent in the mold release can dissolve this type of cloth and cause streaking. DO NOT REUSE CLOTHS.

Shop environment and atmospheric conditions can play a major role in aggravating streaking. Hazing can occur when molds are cooler than air temperatures. This can result in condensation being trapped within the mold release coating as it cures.

A lot depends upon the material you are using to patch the mold, how thoroughly the patch material cures, as well as the depth and overall size of the patch. Quick set, talc filled, styrene free, BPO cured putties have advantages in these applications even though they must be over-sprayed with gel coat for a cosmetic finish.

(HELPFUL HINT): Some people find that drilling some small negative draft holes down in the laminate area surrounding the area to be patched helps lock the patch to the mold and reduces the incidence of pull out during the seasoning of the patched area.

Once the patched area has been cured, compounded and buffed, all foreign matter should be removed from the surface using a high quality mold cleaner. Follow this by applying a high quality sealer and release agent following the manufacturer’s instructions.

Sanding, heavy buffing and stripping can open pores of a mold, allowing un-reacted styrene to bleed out of the mold during production. This can occur in seasoned molds as well. Once the mold has been buffed, sanded, or stripped, and all foreign matter removed, clean the mold with a high quality mold cleaner following the recommended application procedure. Then apply a high quality sealer and release agent following the manufacturer’s instructions.

By taking a few precautions, you can achieve the same production from these types of surfaces as from a polished smooth surface. Buildup in non-skid areas generally can be seen as the same color as the spray-up gel coat. The cause of buildup in the grooves of the pattern usually result from either: 1) failure to apply the release into the tips of deep recesses in the pattern which causes small bits of gel coat or resin to bond in the tips with each cycle, or 2) excess release agent pooling in these areas because of poor application technique. When excess release is present, it does not have a chance to dry or cure thoroughly, or to develop full chemical resistance. The release films over on the surface and can attract free styrene from the gel coat or resin used to mold parts. This can occur because styrene in the resin acts as a solvent, penetrating the heavier areas of release and accelerating the buildup and sticking in these areas. To reduce the buildup and sticking concerns, care should be taken to thoroughly brush out and polish the release into these deep patterns without leaving a heavy residue.