That makes sense that a humectant/plasticizer such as erythritol would help out. I've used sorbitol for my dye-imbibition coatings and it's worked very well, though frilling was never a problem.
So a (somewhat) interesting development with Dura-Lar Wet Media. I coated 2 more sheets; 1 that was washed in hot water and 1 fresh sheet. Both coatings are sticking nicely to the surface, which is somewhat perplexing. My thinking was that the wash would destroy the subbing layer and I was hoping to find that it would peel off when dry. I'll cut both sheets and see if frilling is a problem at cut edges.
But as far as my limited testing can determine, Dura-Lar Wet Media is a reasonable option for a film base. Unfortunately it's a little thin, and isn't as ideal as a 7-mil substrate, but hey, it could be useful for a lot of things nonetheless. I too recall that Denise said this base doesn't work, and so that's why I'm somewhat confused. Denise, if you're reading, I'd love to hear more about your experience with it.
If indeed my tests are telling, it begs the question what do they use for their subbing layer? Subbed melinex is definitely destroyed by washing, so I had assumed that this would be true for most other subbings. Interesting...