Sorry for my late reply
Just to summarize:
R17 big OD – Used Polymerics + black background. (tape : white letter + yellow/clear tape) was not OK Semperrock
2SN big OD - Used Polymerics + black background. (tape : white letter + clear tape) was OK MSHA cover
Which branding type you used for former orders for Couplamatic?
Please send me a picture of the R17 + 2SN unused mylar tape -> see the difference on unused tape
Afterwards please make following trials and send me the pictures:
Place R17 mylar on 4420 + 4470
Place 2SN mylar on 4420 + 4470
Vulcanize the hose
Just a short hose piece each should be enough. I want to check if there is maybe an influence from our cover compound.