For me it kinda depends on what I'm working on. With a large piece like the wheel skirt, I only had 4 dishes, and it was taking me 6 dishes per side. So I was cleaning them out in a semi-gelled state. I prefer to let them dry and break free the hardened piece. There is less smell and less stickiness. :-p
If the resin is still semi-liquid and you're done with the dish, you can clean it out with a paper towel.
I do not normally use acetone on the dishes. If I do, its usually to clean the outside. They get sticky spots and/or fiber-resins accumulate on the dish. So the next time you use it, your hand gets sticky from the get go. This usually makes handling new fiberglass more difficult (cause it sticks to you, no the surface your fiberglassing!).
I know I've seen videos on youtube about different fiberglassing techniques. I'll have to see if I can find one tonight or just make one myself.
But now its off to work and dodging school bus traffic :-/
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