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Building Tips and technical articles. => Paint and finishing => Topic started by: John Witt on October 09, 2009, 09:20:03 AM
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I'm bulding a Vector kit and the time is rapidly approaching to start the finish process.
Is it possible/practical to put a coat of Sig sanding sealer on the wing frame, then sand and then apply the Monokote? The object being to get a smooth, fuzz-free surface. I also could do this with LustreKote primer--would that be a better choice? Or just sand it?
I'm worried about the paint turning to goo under the heat of Monokote application and releasing the Monokote's adhesive.
The intent is to cover the wing and stab with Monokote and use either dope or Lustrecoat on the fuselage, et al.
Thanks,
John
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We use Balsa-Rite and Sig's Stix-it over bare wood before a film finish. It is water thin out of the can and dries quickly then you can sand it lightly before you start with the covering. It will eliminate the fuzzies from the bare wood. We have also used thinned clear nitrate dope to seal the wood and had good results with that. These
products help the covering to adhere and also are used for adhesive for some products that have no adhesive on the covering itself. Hope this helps.
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THere is a separate thread on the differences between butyrate & nitrate dopes. I snipped this froma post by Bill Byles:
"Both nitrate and butyrate dopes are available in tautening and non-tautening types. "Tautening" dopes shrink about 12%-15% linearly, "non-tautening" dopes shrink about 5%-6%. Nitrate shrinks slightly more than butyrate but the dried film has a lower tensile strength than does butyrate. Nitrate is not readily available in colors anymore and hasn't been since the early fifties. Nitrate dope (both the liquid form and the dried film) ignites easily and burns almost explosively; butyrate dopes were developed to provide a finish that burns much more slowly than does nitrate (an important consideration if you are flying along in your Taylorcraft at 5,000 agl and develop an in-flight fire)."
I think the lesson there is do not be too quick to use nitrate dope under a surface you intend to heat up!
THe best way I have found to de-fuzz the balsa under cote or dope is to "sand" id with a piece of foam rubber. It seems to dust off and remove the fuzzy semi-loose fibers for the surface. Really improves surface adhesion of iron-ins too...
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Thanks, folks. I think maybe I'll do a couple of test pieces. I don't intend to put much dope on the surface--actually Sig sanding sealer. One coat or maybe two thin ones, and probably sand off most of that.
John
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I wouldn't put anything but bare wood under Monokote.. Get it just a tad too hot and you will have a bubble you can't get rid of. Put the covering on first then paint, overlaping the edge slightly. Skuff the plastic with a Scotch Brite where you are going to apply paint.