Faults in Painting Plastics - Pinholes
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Pinholes due to pores in the plastic., 20 x magnification
Definition
Small holes in the paint surface due to pores and bubbles in the plastic. This problem often appears on the soft flexible parts (e.g. PUR rear spoilers) and GRP fibre-glass mouldings.
Causes
1] Expansion faults or foam holes in the plastics from production.
How to avoid
1] Thoroughly check the plastic part for pores before painting. Then fill the pores using Glasurit 839-90 Plastics Body Filler grey.
Repair
Porous paintwork can, in principal, be repaired using the pore filler wiping process. Scuff sand the surface, fill the pores with 839-90 and refinish the area to be painted. Note: Too many pores in the plastic will make it very difficult to paint. It is important to check the plastic for pores thoroughly before painting.
Advice on Paint and Paintwork Defects