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Building Tips and technical articles. => Paint and finishing => Topic started by: Tim Wescott on June 11, 2010, 01:51:40 PM
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So, I'm doing a test piece. I sanded a small balsa block to look sort of "cowl like", primed it with Minwax Polycrylic, sanded, applied silkspan with Polycrylic, painted, sanded, painted, sanded.
I have some questions:
What do you usually use as a filler coat over Minwax? More Minwax? Minwax and talc? Some other filling primer?
If you use Minwax, how do you tell if you're sanding through? What can you color it with?
At some point I have to call this good and paint with Rustoleum, but I'm having fun with how nice the process is, and the fact that I don't have to step outside to do it.
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Tim,
I have used Rustoleum primer and Minnwax with talc for a filler. The talc takes fewer coats than the primer, but I have always brushed it on and the brush marks are a pain to sand out. I prefer the primer, just takes lots of coats. The only way I can tell if I've sanded through the Minnwax is when the wood starts to fuzz. I can also feel the difference in the friction of the sand paper as I start to sand into the wood. Having said that, I don't sand to a perfect finish until I start using the primer so I seldom ever get to the wood. The primer will fill any slight roughness of the Minnwax. I've tried wet sanding the primer, but it's more trouble than it's worth. I just keep wiping the paper on a dry towel to keep the grit clean. Hope this helps.
Paul
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You might tint the Polycrylic (water base) with Rit dye (from the supermarket or drug store) for the last coat before primer. That should show some color when you're getting into it. Dry pigments from the auto paint store should also work. "Should" being the key word!
If you want to mess with talc in Polycrylic, I think it might work really well. I've used it in "last year's color" epoxy paint on speed models, but epoxy is heavy, and so is talcum powder. You might try mixing in some Zinc Stearate (Randy Aero). Nobody has reported on that combination, so please do! The Zinc Stearate in Finishing Epoxy would be great for a wooden cowl. #^ Steve
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I would say if lyou appllied silkspan over the base coat you do not need talc or sterate in the clear/primer coat. Put two coats of clear over the silkspan and rub down the roughness. Very fine sandpaper. Two more coats of clear and sand. You should be getting a kind of matte/shiny finish. It really depends on how thin you do the dope. The way I thin dope it usually takes 4 or more sessions of 2 coats and sand. Let the dope set at least a day before sanding. H^^
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I would say if lyou appllied silkspan over the base coat you do not need talc or sterate in the clear/primer coat. Put two coats of clear over the silkspan and rub down the roughness. Very fine sandpaper. Two more coats of clear and sand. You should be getting a kind of matte/shiny finish. It really depends on how thin you do the dope. The way I thin dope it usually takes 4 or more sessions of 2 coats and sand. Let the dope set at least a day before sanding.
Dope? The only dope in the process is me!
I'm applying the silkspan with the Polycrylic. It appears to look great -- I've got the test piece painted up, and aside from two known problems (dust in the finish and some orange peel on one face from trying too hard to get the last bits of primer out of a dead spray bomb) it looks very good. I'm letting it dry thoroughly then I'm going to put some fuel on it to see how it stands up.