Yes, I realize the foam is only there to keep the canvas in the desired position (as well as other things attached to it) and the important bond is to the floor. I thought people get away with 25% water as the foam does not absorb the water. I did find the 100% TB did hold the canvas a little better but that might also be because it stiffened up the canvas and I had to overcome some of the bending strength. Hard to say with my un-calibrated hand. I really wanted to try the paint as a bonding agent. It seemed to do as well as the watered TB. I have read a few different options to stick the canvas down and I had no idea how they compared to each other so I tried it to give myself a real life experience. I am still unsure what to think.
The scoring with a wire brush is something I did not think of. I thought of putting a wire wheel on a drill and go at it but thought it might be a little to extreme. Time for a few more tests I would think.