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Thread: painting balsa wood?

  1. #1

    Default painting balsa wood?

    Anyone know of a simple way to paint balsa wood?

    I am thinking you need to:

    Sand the surface
    Apply primer (?)
    paint
    sand again (?)
    apply another coat of paint
    then use a few coats of a glossy varnish

    Any ideas?

    Erik

  2. #2
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    Quote Originally Posted by eknuds01 View Post
    Anyone know of a simple way to paint balsa wood?
    Sand it smooth to where you like it. Apply a sanding sealer to seal the pores & grain of the wood. Prime, sand some more & paint.
    What are you using it for?

  3. #3
    Classified Forum Moderator Dreamer's Avatar
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    Yeah, "Tube60" is right. You need to apply a "sanding sealer" to Balsa before priming. Most primers are going to just soak right into th egrain of Balsa, and you'll probably end up putting several coats on, with less-than-satisfactory results. You can get water-based sealers at any good hardware store, so cleanup is simple, and they aren't too stinky. It's thick stuff though, sort of like a watery Elmers glue, and you need to put it on with a minimal amount of fuss, because it doesnt like to be "gone back over"--it tends to show brush marks if you work it too much.

    In the model airplane world, they make stuff called "dope" that is a REALLY thick laquer-based paint for painting balsa, cloth and paper. It's so thick that it doesnt really absorb into the porous materials as much as sit on top of them and then dry into a hard, smooth finish. IT's REALLY stinky though, and a HUGE pain to deal with because it doesn't brush well, and it tends to skin up quickly, making it tough to go back over spots you might have missed. I don't even know if the "good stuff" is available anymore. If I remember correctly, back in the day it was made with toluene as the solvent, which is REALLY evil stiff--volatile, carcinogenic, and flammable as hell. But man, did it make for a great finish on porous materials...
    Last edited by Dreamer; 02-14-2009 at 03:50 PM.
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  4. #4

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    Thanks, guys.

    It's for an underwater submarine. We are having a contest at work.

    Erik

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    Quote Originally Posted by eknuds01 View Post
    Thanks, guys.

    It's for an underwater submarine. We are having a contest at work.

    Erik
    Dreamer is correct what you are looking for is the model airplane 'dope', and the sanding sealer they use for it. The last time i used it in the late 70's the solvent was either toluene or acetone. Use in a very well ventilated room.

    You will need several coats of sanding sealer (about 3), sanding between each one, followed by two or three coats of color. The stuff I last used was very thin and working time is quick (The toluene evaporates quickly).
    Burke
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  6. #6

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    Take 30 min drying Epoxy and dilute it 50/50 with rubbing alcohol and brush on a few coats and it will seal and harden at the same time. We did it when building model boats for scale unlimited s. When you get a few coats wet sand it with 400 and its should be glass smooth
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  7. #7

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    Quote Originally Posted by C.A.P View Post
    Take 30 min drying Epoxy and dilute it 50/50 with rubbing alcohol and brush on a few coats and it will seal and harden at the same time. We did it when building model boats for scale unlimited s. When you get a few coats wet sand it with 400 and its should be glass smooth
    What is 'wet' sanding?

    Also - it seems that you want to seal and sand it smooth prior to painting, right? That way you have a nice flat surface for the painting?

    So you seal with a smooth varnish after painting too?

    Erik

  8. #8

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    First coat of diluted epoxy, Apply.

    It will dry in 30 min . That coat will absorb right in.

    Do another .

    Once you start to see finish build take 400Grit Wet Dry paper . Its in the auto stores.

    Wet the paper well with water and sand lightly to smooth out the finish. When real smooth with no pores you are ready to prime. I have used this with several wood boats and its great !
    Krell fpb 300cx
    Krell KPS25sc
    Martin Logan... CLS Ia... Walnut frames

    My system here

  9. #9

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    CAP - any paricular brand of of min exoxy that you recommend?

    How about the primer?

    thanks!

    Erik

  10. #10

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    Devcon 30 min epoxy. As for primer any Auto primer and auto paint !
    Krell fpb 300cx
    Krell KPS25sc
    Martin Logan... CLS Ia... Walnut frames

    My system here

  11. #11

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    CAP -

    This worked out OK. However, maybe the epoxy wasn't very good (?). When I mixed teh hardener and epoxy 50-50 with alcohol - it was really this soupy mixture. I don't think the the glue and alcohol mixed together.

    I did apply a coat, sand it, and then I applied another coat. I used the 400 grit sandpaper and I didn't sand it the 2nd time. It just dried smooth.

    Also - this idea seemed to work best when I allowed the mixture to cure a bit in the cup (become thicker) and then apply it to the wood.

    thanks again for all of your help.

    Erik

  12. #12
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    Quote Originally Posted by eknuds01 View Post
    When I mixed the hardener and epoxy 50-50 with alcohol - it was really this soupy mixture. I don't think the glue and alcohol mixed together.
    Next time, use acetone to thin epoxy. It's much more predictable than rubbing alcohol; the extra water present often interferes with the dilution process.

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