ReNae:
The reason I say "pure polymer medium" is because many craft and art glues - like Elmers are made from acrylic polymer, but they are often adulterated with things like corn starch or other additives that make them unsuitable for longer term adhesion of linen to board. Over time, glues like Elmers turn to powder due to the additivies.
Pure polymer medium is typically in the acrylic section. So things like Golden's gloss medium is just pure acrylic polymer. Also, Gamblin's PVA size is similar. The thing is to get a pure acrylic without any additives in order to increase the amount of time the linen will adhere to the board.
Remember, plastic is forever.
