|
October 30 - November 5, 2016
What causes blistering/crater formation in freshly applied polyurethane topcoats, and how can this be avoided?
Selected Answers
From
Emil Langiewicz of AkzoNobel on
January 12, 2017:
Blistering is caused by reaction of isocyanate (curing agent) in direct contact with water (condensation) where carbon dioxide and alkaline chemicals are formed. Please check pH of the blister fluid to confirm it.
From
Bryant Chandler of Greenman-Pedersen, Inc. on
November 4, 2016:
If the blistering/crater formation is random but in a vertical pattern on a tank shell, I would suspect the hoist motor spitting out oil droplets when going up and down. Other random spots could be caused by power tool air motors spitting out oil, especially if recently lubricated. I have had contractors wrap cloth around the discharge port on air or electric motors to eliminate a problem or potential problem.
From
Paiboonsak Saengsomboon of JT Marketing Co., Ltd. on
November 4, 2016:
It should not be called blistering, maybe bubbling, If so, the surface must be very rough and porous. In the case of craters, the surface may have oil, grease, silicone or others contamination. Before topcoating , you have to inspect the surface. It must be very clean with no contamination.
From
VCBud Jenkins of CSCS on
October 31, 2016:
An unclean, oily surface is the most common reason for craters. Clean it with soap and water or solvent and rinse it well. Sometimes sanding it will help remove the incompatible surface spots. First, make sure the coating does not have any craters of its own by spraying another clean surface and examining the result.
Please sign in to submit your answer this question
Tagged categories:
Asia Pacific;
Blistering;
Coating failure;
EMEA (Europe, Middle East and Africa);
Latin America;
North America;
Polyurethane;
Topcoats
Current PSF Question
| Submit a PSF Question
| Full PSF Archive
|
