We have a kynar coated metal roof that was primed with an acrylic primer and then coated with a dark blue acrylic elastomeric paint. It was coated during spring with moderate weather. The roof surface was dry. Within a few days the coating blistered severely. The blisters were cut out; only the coating was delaminated, the primer was well bonded. Some of the blisters held moisture, most were dry. The blisters were cut out and the roof was reprimed and recoated. The coating blistered again as it had before. It was then revealed that the dark blue coating had been blended without a tint base; the pigment was added directly to a white or gray (or a mixture thereof) paint. We suspect that the CPVC was greatly exceeded when the blue pigment was added to the white and/or gray paint, would this cause the coating to blister? What test needs to be performed to determine the PVC?

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    $\begingroup$ Could you please define PVC and CPVC? I guessed they were acronyms for polyvinyl chloride and chlorinated polyvinyl chloride, respectively, but that does not seem to work with “determine the PVC” and “the CPVC was greatly exceeded”. $\endgroup$
    – Ed V
    Apr 5 at 20:16
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    $\begingroup$ PVC in the paint industry is an acronym for Pigment Volume Concentration; CPVC is the Critical Pigment Volume Concentration. (See article at this site - link below) chemistry.stackexchange.com/questions/142980/… $\endgroup$
    – Lee Allen
    Apr 7 at 12:17
  • $\begingroup$ Ah, now it makes sense! Unfortunately, I know nothing about this, but your link may be useful: maybe post a comment to James Gaidis at the link you provided. He is a helpful fellow. $\endgroup$
    – Ed V
    Apr 7 at 12:37

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