Spalted maple finish question

Discussion in 'Luthier's Corner' started by Mr M, Aug 21, 2009.

  1. How can you pop the figure and colors of a spalted maple top?
    I have a bass with a spalted maple top that I'm not happy with the finish for a long time. I plan to sand it to bare wood and finish it again.
    Before it was finished (when I've first bought the lumber), when dampened with a wet tissue, there were some green and pink areas alongside the black and brown lines of spalt. But after the luthier has put the finish, the colors disappeared and the top became very yellowish.
    Here is my plan and I'd like to hear suggestions:
    After sanding down to bare wood (and paying attention not to inhale the nasty dust, of course) I plan to use denatured alcohol (I've read somewhere that it would pop the figure and colors, but I'm not sure).
    Then I'll put some clear gel coat (hopefully I have the access to polyester and gel coat in my work).
    Then clear polyurethane(?) as a last top.
    What do you think about it? Any suggestions?

    I've read that Minwax Wipe-on poly may work but unfortunately I can't get it, it's not sold here locally (nor a substitute) and as it is inflammable, I can't order internationally :(
  2. mikeyswood

    mikeyswood Inactive

    Jul 22, 2007
    Cincinnati OH
    Luthier of Michael Wayne Instruments
    Sounds like you will have to redo that entire process every year to keep the look that you want.

    The colors disappearing are from the natural aging and oxidation of the wood. A good oxygen and UV block will slow the process but nothing will stop it.
  3. Maybe I was not clear with my first message. It did not fade by time. It was always like this after the luthier who built it, put the finish on it. So I want to correct that finish that IMHO doesn't show the potential of that top.
    I know there should be a way to finish more correctly because the wood unfinished was really beautiful.
    BTW I'll consider a UV blocking gel coat which I can get pretty easily as well. Thanks for that suggestion.
  4. Alcohol by itself will do nothing to pop the grain - it will evaporate for the most part - and if it doesn't, it could prevent your clear coat from curing fully if it is not compatible with it.

    What is the original finish?

    Sanding spalted maple down to bare wood is asking for trouble if you don't have much finishing experience - the less-hard parts of the wood will erode much faster than the firm parts, and you can quickly create large valleys in the surface if you don't stabilize it first with CA or epoxy.
  5. gyancey

    gyancey Supporting Member

    Mar 25, 2002
    Austin, TX
    Polyurethane can be anything but clear - it is a very yellow finish. Order a water based finish - it can be shipped to you and they generally trend towards a "cooler" shade than polyurethane.
  6. tjclem

    tjclem Commercial User

    Jun 6, 2004
    Central Florida
    Owner and builder Clementbass
    I prefer to think of it as golden.....sounds better than yellow.... :smug: but you are correct... And yes it is a pain to deal with!

    What finish do you suggest Greg? And will it handle humidity?
  7. mikeyswood

    mikeyswood Inactive

    Jul 22, 2007
    Cincinnati OH
    Luthier of Michael Wayne Instruments
    Minwax's Acrylic is readily available and adds no amber to the finish.
  8. I sincerely don't know what is exactly put as finish. I'll be careful when sanding it.
    A water based finish or an acrylic looks logical.
    Will the acrylic finish result in yellowish color too?
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