On the recommendation of several folks on this board, I got some Gunze Sangyo Mr. Surfacer 500 as a filler. As represented, it's great stuff, and it's making some filling/smoothing on my current project much, much easier than it would have been with putty. I've been applying the Surfacer with a regular paintbrush, then cleaning with some turpenoid and alcohol. Seems to be getting most of the stuff out of the brush, but there's probably another thinner that would be even better. Anybody know what you're supposed to thin this stuff with?

Should you not use celulose thinner for this nasty stuff ...but ugg...I hate the stuff...it gets the plastic attack award from me

The only thing that works is another Gunze product- Mr. Thinner (aptly named )

I use either laquer thinner or testors liquid cement with MR Surfacer to clean it up off the brushes