Unknown Print problems

[raj9469]

Hello Friends,

I have a problem here. I am printing on a PET sheet on Heidelberg SM74, 4 colour press, which is specially coated with release agent for heat transfer printing process. I have 2 different kinds of Sheets here, Type - 1 and Type - 2 as you can see in attached picture. I have rounded up the problem in red, I dont understand this problem. As you can compare in both pics, there are some peel off of the colours especially in black colour.
Does anyone have an Idea about this? What and why exactly this? Both substrates are of same microns.

 

[realaqu]

my wild guess, using a ph test pen to check if the paper is acid free and leave them in room temp at least 72 hours

 

[turbotom1052]

may want to try bringing up all 4 colors about 15 percent and increasing pressure by about .004"