Guys:
I used a 50/50 solution of glue & water over top an acrylic painted plaster terrain.But every time I touch it some falls off. Can I spray something on top of the grass to keep from falling off.

Three things - pour on LOTS and press it in when you first apply the grass. I put down at least .25" of grass. Then press it in and then let it sit just a bit, then dump it off.
Thing two - you might try hair spray to cover it.
Thing three - don't touch it. Yea yea I know how do you do that. Its tough. My dio The Fall was a nasty little booger to get around and not touch the ground or knock the trees. I did what I could not to.