by Ron Joseph
Water Break Free Question on CARC Paint
Q. Mil-DTL-53072, section 18.104.22.168 addresses condition of surfaces prior to painting. It requires the performance of water break free test just prior to painting.
Does the definition of "paint" include or exclude the wash primer and CARC primer?
For parts which are sand blasted, wash primed, CARC primered and CARC painted ... does the water break free test have to be performed before each "paint" coat, i.e. before wash prime, again before CARC primer and once more before CARC top coat OR is the intent of the document to do the water break free test only befor the CARC paint top coat?
A. I haven't seen MIL-DTL-53072, but in my experience the water break-free test is only performed immediately after preparing the substrate. This test allows one to determine if oil and grease still remain on the metal after abrasive blasting, wire brushing, solvent wiping, or whatever method is used to prep the surface for painting. Once you start to apply the coating system, (wash primer, primer, ... ) there should be no oil or grease unless someone were to poorly handle the painted parts.
Therefore, my answer is that you perform the water break-free test after abrasive blasting.