I have just found out, by a sudden moment of strange inspiration, how to prevent delamination of the first few surface layers of paper mache strips.
When using boiled wheat paste as a glue for paper mache strips within a negative mold, the release layer of paper towels or toilet paper and water, were always diffcult to really paste down and merge with the rest, once pulled out of the mold. Even worse, most times, some areas of the glued paper lift when applying the sealer.
I never had those problems with PVA glues.
I now use a paper pulp (with wheat paste as a bonding agent) to make the detail coat into the molds. It takes twice as long to dry, but that time is not wasted, as I get a better definition, and a bonus texture that I love. I then add 3 or 4 layers of thick Kraft paper inside, for the strength and stiffness I need.
See the method here:
I'll repeat it here, to be clear: Wheat paste paper mache is far more stable in temperature changes than any PVA I've ever tried.
PVA-glue paper mache strips: get it cold, it becomes brittle and can break into pieces if dropped or hit; get it hot, it becomes soft and can be warped or squished out of shape.
Boiled wheat paste paper mache strips: no apparent change! I even froze a puppet head for a few hours, and then hit it violently, there was no change in strength!
Add to this that wheat paste paper mache is by far stronger than PVA-based same, and you got the best choice: stronger, non toxic, smoother results, non-lumpy, very economical, available worldwide!
This is where I got the info that made me want to try wheat paste again, at last!
Thank you Jose Chavez!
And here is the previous article I wrote about Wheat paste and my newfound love for it: