Updated 8/11/2018:
I got the layout room walls sealed with Zinsser Peel Stop, which I had to buy on-line (store didn't carry it). They make you buy 4 cans of the stuff; I barely used half a can. The other 3 cans are going on Craig's List.
It will probably be the same deal for the wallpaper adhesive. Anyway, it's done.
I will let it dry for a couple of ours and see if it needs another coat.
More when I know it.
George