Material

Cratering / fisheye / silicone contamination

Small round craters or pits in freshly applied varnish - the surface tension around impurities (silicone, oil, water) pushes the varnish away from the center, creating a characteristic fish eye. A lower layer is visible at the bottom of the crater.

Cause

The substrate was not properly degreased before painting
Dirty or used degreasing cloths - they spread contaminants instead of removing them
Contaminated compressed air - oil or water from the compressor system
The spray booth is contaminated with silicone - a trace amount is enough to cause a defect
Products containing silicone used around the cabin - maintenance products, lubricants, sealants
Soot from the oil radiator or dust from the spray booth
Wrong remover - too fast remover does not remove dirt effectively
Lack of regular service of the oil and water separator in the compressor installation

Prevention

Thoroughly degrease the substrate before each stage of the repair process - wipe it dry with a clean cloth
Use only recommended removers suitable for the given substrate
Use clean disposable degreasing cloths
Regularly check and clean the oil-water separator in the compressor
Do not use any products containing silicone near the spray booth
Keep the cabin and work environment clean
Have your radiators and cabin heating system serviced regularly

Repair

Thoroughly degrease the entire substrate - remove the source of contamination
Sand the defective layer until smooth
Apply a thin layer first - the so-called "gasoline layer" which will reveal whether the contamination has been removed
Ensure proper flash-off time between coats
If craters still appear - identify and remove the source of contamination in the cab before continuing operation