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Howdy gang-

I have this joined spruce top that has warped on each side across the grain (top is straight along the grain) and is in an "S" shape. It has a rosewood rosette, if that makes a difference. How can this be fixed so it's flat? Gentle heating, wetting or weight and stickering? All of the above? Something else?

Thanks and please help-

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John Lewis
Wannabe builder owned by 2 crazy dachshunds

John, I've seen tops warping like this before due to low humidity...
I had one warp some and I placed it under a flat board for a couple of days, it still wasn't perfect but the bracing brought it back to shape.

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Peter M.
Cornerstone Guitars
http://www.cornerstoneukes.com

Flip it over and my guess is that it will be flat by morning. Don't worry about it much. Just brace it up and it will be fine. Though, you might want to keep an eye on your humidity.

Are you controling humidity? If so, how long have these parts been controlld?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

What Paul said.

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Dave Rector
Rector Guitars

yep this is purely a humidity issue. Sticker it, and control the humidity and
within a few days it should be golden.

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John Mayes
http://www.mayesluthier.com

If the simple fix of flipping it over doesn't work, it may have warped from uneven stresses in the piece set up when it was thinned down. I have had success in wetting the concave side and bending it back over a small batten using weights on each of the sides sticking up. Put the batten under the deepest part of the curve, and weights on each side to hold the sides down. It may take a day or two for a stubborn piece.

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain

Agree with the others, if it started out flat it can go back.

Also: Never hold your top up in the window!

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

Not a problem. Humidity issue. You want to maintain 45% to 55%. If that isn't possible place this between some weight for a few weeks and brace it up when your Relative Humidity is in the 40% range. You won't have much trouble once the braces are glued in.
   Humidity can cause alot of funny things to happen to wood
john hall
blues creek guitars

Thanks all for the advice. This is a really nice Italian Fiemme spruce top that is cut out to a Martin 0-12 fret shape. I got it from a pretty decent fellow we all know here on the forum. I want to build a 25.7" scale fingerstyle guitar with 13 frets to the body with this top. I've got a small Cuban mahogany back and side set this may go well with.

Unfortunately, I have no way of controlling humidity and it is down to about 29% now. I guess everyone is right about humidity doing bad things. I'll have to weight and sticker it and wait for the humidity to go back to normal.

Thanks again everybody-

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John Lewis
Wannabe builder owned by 2 crazy dachshunds