Blistering, bubbling due to moisture
Organic and hygroscopic substrates retain moisture longer
Poorly cleaned substrates can leave moisture in the substrate during osmosis. Possible causes of osmosis damage would be salt residues that were not removed.
- Sources of error:
- Polyester material -filler- was wet sanded during the preparatory phase.
- Wood was rubbed or even washed down with water before coating
- No time made for drying possibilities. Wood, for example, needs a long time to release residual moisture
- Substrate not properly cleaned
- Water residues from corners, edges and behind moldings not completely removed
- Error prevention:
- Do not wet organic (e.g. wood) and hygroscopic (polyester filler) substrates with water. If necessary, let it dry for a longer time, to be sure, that the residues moisture is evaporated
- Dry sand sensitive materials such as polyester filler
- Bring cold surfaces to room temperature first. Condensation forms and can thus dry off
- Clean surfaces properly with suitable material
- Thoroughly blow out wet sanded objects with compressed air and dry them with two rags to remove the last residues.
- Repair path if possible:
- In this case, only complete removal of the coating down to the bare substrate will help. Then carry out a professional paint job again
- Sources of error:
It is possible to see how the damage was caused. If, for example, a surface ready for painting is touched with bare hands, it may be that hand sweat containing salts remains on the surface. These are then „painted in“. By diffusion during osmosis, the salt attracts the air humidity and forms white crystals or tiny bubbles. In some circumstances, entire fingerprints can be seen.
If only straight streaks form, the defect was caused by poor previous cleaning of the surface. Cleaners must always be wiped out dry. Here it is recommended to work with 2 cloths. One for wiping and one for drying. Some cleaners also contain ingredients that react with the humidity in the air.
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Here is a short video of underground damage with bubble formation
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