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Help my cupped top!

Discussion in 'Luthier's Corner' started by Ironfingers, Feb 8, 2013.

  1. I found a really nice walnut board at my local hardwood place so I had them resaw it for me. The crappy cel phone pic doesn't do it justice.


    It had cupped by the time I got it home. I was ready for this though. I wet the concave side, stickered and weighted it for a week. It's still cupped. In fact it didn't flatten any at all.



    Should I try again and leave it longer? Try something different?
    Is this top toast? I would really like to salvage this and use it if at all possible.
  2. You could try two things...
    1. Leave it longer and see what happens.
    2. Apply water to the concaved side. The wood will swell and may even out.

    How thick is it?
  3. It's right about 1/4". I did wet the concave side liberally with water so I'm going to go ahead and try again and leave it longer. I just thought it would flatten at least a little. But no.

    I was just wondering if there was some other secret technique I haven't read about already... :)
  4. wet towel, and iron

    next is steam chamber really
  5. suraj


    Oct 1, 2008
    Mumbai, India
    Since its a 1/4" thick, it should bend with just water. Wet the concave side like your doing, and place the board on a flat surface wet side down. This will ensure that the convex side gets plenty air, and the wet side doesn't get much air and remains moist for a longer period of time. Use a fan on the convex side if possible. I must say, the only experience I have with straightening wood is with my ~1/4" thick wood cavity covers, and this method worked for me.
  6. Thanks guys. I didn't think about steaming. I stickered them every 2" with the concave side up, weighed down with about 50lbs of steel. I was really surprised it hadn't moved much at all. I'm going to try the steam first. I have access to an industrial clothes steamer.
  7. lbridenstine


    Jun 25, 2012
    Did you clamp it, weight it, or just lay it down and let it flatten itself out? I want to try to flatten out my fretboard that I removed so I can use it for pickup rings. I might try your method first.
  8. suraj


    Oct 1, 2008
    Mumbai, India
    I tried clamping it hard against a flat surface, but dry, with no positive results. I tried the same thing by wetting the concave side, no result. In both case I had clamped for 48 hours each.

    the method I described above didn't work in one go. The water would bend it in the expected direction but after drying it would go back, although not completely IF you exposed the convex side to air and blocked airflow to the concave(wetted) side. I had to do this once a day for a few days for it to even out.

    I'm no pro at this, its just the method I tried and it worked for me.

    EDIT : My theory is, with clamping, the caul covered most of my piece, and it was clamped against a flat surface, so both sides weren't exposed to air, which makes conditions sort of equal on both sides. But when I simply wet it and placed in on the surface, the unequal air drying caused the wood to give up its warped state. I guess stickered weighting also would expose both sides to equal amounts of air, so the drying of the wetted surface would bring it back to its warped state. All IME.
  9. lbridenstine


    Jun 25, 2012
    Alright, I'm giving this a try. Thanks.

    Ironfingers, let us know how the steam goes.
  10. I'm trying Suraj's method 1st. It's busy at work right now so I couldn't access the steamer. I was too tired to deal with it anyway. I worked 65 hours last week on top of doing a CAD project for another TB'er.

    Today is my day off, so I'll report on it after I go back to work tomorrow. (Oh the joys of working 6 days a week). I'm not that concerned at the moment. I haven't even started making sawdust yet. It'll be a while before I need it.