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Building Tips and technical articles. => Paint and finishing => Topic started by: Douglas Ames on January 01, 2010, 02:37:08 PM
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I've never used the Minwax PC (waterbased) but read good things about it.
Which weighs more? (finished)
What about sanding, does one require more effort than the other?
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No idea on weights (though I would imagine that the polycrylic is lighter - just a guess). but remember that the polycrylic IS water based. Not a real good idea to paint it on bare balsa (you can imagine how I know).
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I agree with Randy, when all the hype about polyrylic hit I bought a can but just couldn't make myself use a water based product on bare balsa. Still have the stuff but probably wont ever use it on anything model related.
When I use finish resin I wipe as much as I can off with a paper towl. One advantage to finishing resin is you can fuel proof everything that needs it while you have a batch mixed up.
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The water soluble means it can be cleaned up with water. It is already thin for brushing. I use it to seal the wood. Sand it real smooth to the touch and apply a second coat. It is almost like applying epoxy finishing resin with out the mess. Makes for a very hard surface to the wood. I have even applied fiber glass with it.
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When I use finish resin I wipe as much as I can off with a paper towel. One advantage to finishing resin is you can fuel proof everything that needs it while you have a batch mixed up.
I'll remember this. I noticed it goes on inconsistent when thinned with acetone. I know some of it is caused by the balsa. Just makes for more sanding.
Maybe I'll build another 1/2A and experiment with the PC. My curiousity is up.
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Ty,
I use the polycrylic all the time. I've never tried spraying it, but I have tried the rattle cans. Absolute mess!!! Tried all the tricks I know including "hot potting". The spray pattern just splattered the stuff. I almost never got the finish sanded back to smooth. If you try a spray gun, it might take a little tweeking to get everything set just right. I've had good luck using the foam brush method applying very thin coats, usually two, sometimes three.
Paul
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The weight is pretty much determined by how much you put on. Most of the time a minmum layer that looks solid and smooth will weigh the same regardless of the finishing method. Epoxy is denser so it will weigh more if the finish is the same thickness, but you may be able to use less and still get a solid coat, keeping the weight the same.
When using polycrylic over balsa the trick is to apply 2-3 well-brushed out coats, drying in between, and then sanding after it has dried thorougly- 2-3 days. Three coats will come up to a fairly smooth even finish that can be sanded as much as needed. Trying to sand after each coat just takes hours and hours of time.