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Experiencing pinhole paint defects

Dear All,

We have been trying to spray out 2K Solid colours on MS/GI/Al panels. but we always end up with pin holes problem. We are having a spray booth which is in Ok conditions,the spray guns are also in good condition,the oven is also working fine,.....but we are not able to track down the main rootcause for the paint defects.
I would also like to know about the role of flash off time in determining smooth paint finish.

Thanks and warm regards

Amal Vikram
Paint Technician - Vadodara, Gujarat AND India
2007

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Hello:

The flash off time is very important. Please allow the recommended flash-off time before your topcoat any primer. Pinholes are by definition caused by loose trapped solvents in the primer/substrate or under the topcoat. When you force dry/ air dry the topcoat without letting these solvent evaporate first, the topcoat dries up as a film over them. Sooner or later, these solvent need to get out and they cannot condense back to the liquid form and mix with the solidified paint. So they will find an escape route and will cause the pinholes.

So, make sure you maintain proper cleanliness and allow sufficient flash off times.

good luck

3Lok

Trilok Mugada
- USA
April 24, 2008