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Is there a need to "harden" a maple burl top? Also, a walnut question...

Discussion in 'Luthier's Corner' started by Basschair, Sep 24, 2005.


  1. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    Here we go again :rolleyes:

    I'm starting on basses 2 and 3 (and 4 as an experiment). #2 will have a maple burl top, bubinga lam, and Af. mahogony body. The burl is somewhat soft wood, and I'm wondering if I need to treat the wood with anything to harden it so that the knobs fix securely to it without damaging the wood? Or, do I need to go fo a specific finish that will harden it. I was originally considering a satin polyurethane, but am up for suggestions...

    Bass #3 will be walnut burl, wenge lam, and walnut body. Larry (who is THE MAN, in case you didn't know) mentioned that some luthiers fill in the small holes in walnut burl before finishing. What do you use to do this, or do you not fill them?

    Bass #4 (experiment): Got some chunks of walnut (very nice curl, but they milled it so that I can't take advantage of it) and a plank of bloodwood. I cut/planed it all so that I could glue up a multi-piece body with alternating strips. The neck will be walnut and bloodwood: I'm hoping this mixture will produce a stable neck. Anyone tried this mix before?

    I'm taking my time with these basses and slowly picking out the hardware and electronics, learning wiring, waiting for a 6 string set of Fat Stacks to be wound, etc. Hope to have some pics at some point.
     
  2. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    So I guess that means "no," "bubblegum," and "yes?"
     
  3. Use epoxy to fill the voids in the Walnut. The craters are usually so dark that they don't need a colored filler - they will appear dark even with just a clear epoxy. Fill them to above the surface of the top so that any shrink back will still leave enough to sand smooth and even with the top. You could be creative and use a crushed stone in your filler if you have voids in the wood that present an interesting pattern and are plentiful and large enough to make a visual impact.
     
  4. Basschair

    Basschair .............. Staff Member Supporting Member

    Feb 5, 2004
    Stockton, Ca
    Thanks Ham. Any idea on whether or not the maple needs to be treated with something to harden it?
     
  5. Yes, the burl will need to be stabilized. When you try to carve or sand, the softer parts will wear more quickly than the harder parts and you'll get all sorts of humps if you don't.

    Clear epoxy is one way, and cures super-hard, but it will impart some ambering to the maple.

    Cyanoacrylate (CA, or super-glue) is also a good way, but use a respirator (not just a dust mask) and do it outside (standing upwind) or the fumes can permanently damage your eyes and do baaaadddd stuff to your lungs and brain. Epoxy is safer.

    I did a spalted maple top with CA and ended up using three 2 oz. bottles of the stuff. If you're carving, have the rough carving done first, then apply the CA. You'll need several cycles of CA and sanding before you'll be able to get everything smooth.