I jut did a little test. All of these puttys have been dried for months. I wetted a Q-tip in laquer thinner and was able to soften all three. The perfect putty was most affected, Squadron the least. Then I tried plain water. The perfect putty was again softened, the Tamiya and Squadron were not. Aside from that, the Tamiya putty is very fine, but seems to shrink the most. The Squadron and perfect don’t shrink as much. The squadron is the most durable I find, but it is a bit grainy and not as smooth as the others. YMMV.