Peeling powdercoating caused by remnants of PVC protective film?

Bit more info required here.
What is the powder being used? Polyester? Epoxy? Polyurethane?
What is the pretreatment being used? Chromate? Oxylan, any at all?
Do you know more about the film you apply? Whats the reason for it? Low tack tape is available to protect surfaces after powdercoating and during subsequent operations in manufacturing or in installation. These do not cause peeling of the Powder Coating.

On the face of your description, sounds like poor pretreatment in powdercoating resulting in low adhesion. Are any quality tests performed after PC and before you apply this film? e.g., adhesion test?, Machu test?, salt spray? and deformation tests on test panels etc ?

Hi,
We came across the very same problem some two years ago. Our customer manufactured shelters for bus company's passengers who were awaiting their bus service. The aluminium castings showed no defects whilst the aluminium sheet (coated in the same powder coating material) gave problems with adhesion. Prior to contacting us they had come to the conclusion that the protective coating was probably causing the defect. After stripping the protective coating off, they cleaned the substrate with various proprietary degreasers - to no avail. We, as a coating mf, understood the ingredients that made up the strippable coating - they contain plasticisers (no glues used) - these had bleached out onto the metal substrate causing the lack of adhesion. The only solution was to wash the residue off using MEK / methyl ethyl ketone. Beware MEK is a low flash solvent and care must be taken in its use - also the material should not be used in any enclosed space. The usual rubber gloves [on eBay or Amazon] and masks should be provided for the operators. Hope this helps and would be interested in the outcome or any alternative explanations.