And you also agree with Mr.sun that he think PE foam on B surface became deform
>>>>> why we don’t think like that ??? ( try to think, as I’ll say….)
Because.. normally, the headliner assembled with body and B surface will touch on body (all surface) ---- that means both of A and B surface have controlled by other factor.
But your test method is no have jig to control B surface, after heating is normal that B surface became deform due to A surface was stuck with headliner by glue.