I have tried without success of having PVOH polymer, both the Kuraray R-1130 and Poval 217, work well as a coating onto plexiglass. Coating is easy and when dried is hard and adheres well. Once in gets in contact with water again it will float and/or peel off. Both polymers need heat to cure and become insoluable in water and heat required is not good for plexiglass.
Originally Posted by wildbillbugman
As Bill pointed out you can get use one of the anionic polmers such as KL-318 and it will hold strong onto polyester but is still water soluable and will disolve unless crosslinked or heat cured.
Polyvinyl butyral(PVB) works as a subbing agent for plexiglass, PET, PETG, and is only soluable in strong solvents, such as ethanol. Never tested to see how well a gelatin size/emulsion adheres since my experimentation has around removing gelatin from the equation.