I did NOT say they were identical. I said they were similar, ie, they are plastic like, subbed white reflective materials. They all resist processing solutions and all will accept gelatin coatings provided the subbing is correct.

Melinex is a transparent material in most all incarnations I have seen, and the version used must be chosen with the application in mind as it does not always work out right, just as Polypropylene is not always right. Since one of the people here uses Yupo, it must be that he has found a way to work with it in carbon printing, but IDK. His post suggests that it works just fine.