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December 24, 2018

What causes blistering/crater formation in freshly applied polyurethane topcoats, and how can this be avoided?


Selected Answers

From Zenith Czora of Parex Davco on January 28, 2019:
There are few causes of occurrence of blistering/cratering in freshly applied polyurethane topcoats. Surface preparation - dust, oily surface will cause cratering; 2. Wrong solvent blend used in thinning the topcoat for spray application; 3. Air trapped during the mixing process; 4.Application on hot surface or excessive heat during the curing process or excessive sunlight during the curing process. To avoid this problem: ensure the surface to be coated is clean, free from contaminants like dust, oils, or grease; do not use mineral spirits as a cleaner; use the manufacturer's recommended PU thinner or reducer; use the manufacturer's recommended equipment for mixing and application; try to avoid elevated temperatures during application and curing and prevent direct sunlight exposure during the curing process.

From Jonathan Rausch of That's private on January 7, 2019:
Maybe you put the primer on too thick???

From Suresh Setty of Alpha High-Tech Polyurtehanes on December 24, 2018:
One cause is high moisture in concrete, sometimes when the coating is applied without removing the membrane used for curing  and too quick application of topcoats without allowing it to dry properly.

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Tagged categories: ; Asia Pacific; Blistering; Coating failure; EMEA (Europe, Middle East and Africa); Good Technical Practice; Latin America; North America; Polyurethane


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