No "contaminant" like Armoral is going to cause lifting. "Lifting" is caused by solvent getting under the substrate. My first thought is the plastic was originally primed with waterborne primer if this primer is sanded thin or thru it WILL lift. However, if you primed it with K36 that blows that idea. So, at this point, it makes no sense what so ever.
If the k36 held up, ANYTHING you put over it should as well. The K36 should be a "barrier" to the plastic to anything applied over it. So unless the K36 was somehow "soluable" because of improper mixing or something like that, that would explain it.
But other than that, I don't have anything to offer.
