Description:
Formation of small concave depressions or craters when bubbles of air (foam) form in the paint film during the process of dried. 

Possible causes:

1. Use of high speed stirrers to mix the paint, especially if the can of paint stirred is incomplete.
2. Excessive re-touch of the paint film with brush or roller, generating the paint film adsorbs air.
3. Application of a gloss or semi-gloss paint on a porous surface, or on a surface that has not been sealed perfectly.
4. Application of the paint in very hot environments, generating craters in the painting before such craters have time to wipe out.
5. Use of an inappropriate solvent to dilute the paint. 

Solution:

• Once the craters in the paint appear, let the surface to dry perfectly, then sand and remove the dust and then re-touch the surface.
• Stir slowly the painting before applying. Avoid to use high speed machines to stir the paint.
• If you realize bubbles formation during the application, reduce the speed of application.
• Seal the porous surfaces before applying the final finish paint.
• Let the coating or paint to dry perfectly (verify the re-touch time) before continuing with the installation.
• Consult previously the adequate solvents as well as the quantity to use for each type of paint.