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Warped Purpleheart

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i got a top of purpleheart thats been thickness sanded; then it sat around for quite awhile and got quite a twisted cup; do you think if i glue it up in a stack; like two halfs of the body ontop of each other,

i could get them to flatten and hold under the clamps? and would it start to seperate after the clamps are gone?

by the time I plane and sand the warp out im gonna have a mm.

and all of that work isnt worth it

but i dont wanna have to scrap the body wood too


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Trust me, I've had my purpleheart woes... I've ordered a 1/8" top TWICE and am jsut gunna end up covering it anyways... I KNOW purpleheart woes. But warping is NOT a characteristic I associated with this wood... it's some ultra heavy stuff, I've got a couple pieces here in Miami where EVERYTHING warpes when I get it, and that's the one wood that doesn't. Either way, if it's so thin that if you re-thickness it you'll end up with one mm... then chances are you can clamp that bad boy down to your body blank with enough pressure and glue it down with no problem. Thing woods usually give quite a bit. I wouldn't be surprised if that works out for you... granted purpleheart is a pretty strong wood... but get a BUNCH of clamps on there all around it, glue it down to your body blank, and set something like a drill press in the center (that's what i use as a "clamp" to hold down the centers of glueing tops on) and I bet you'd be set...


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Two questions:

1. Did you sticker the wood when you got it? and was it stored properly after it had time to stabalize?

2. How bad is it cupped and twisted, give some unit of measurement.


You may be able to flatten the wood to some extent if the cupping and twisting is not too bad. It will take time and patience. Is it worth the time and effort- that is up to you. If you have other wood that has not been cared for properly sticker it now. After ithas had time to stabalize stack it properly. Monitor your humidity! You spend a lot of money on wood and effort on trying to make guitars that will last. Spend a few dollars and get a meter (even a cheap one is worth having so you can see radical changes).


P.S. There are a LOT of guys that have this problem everytime the season changes. This is your chance to get that meter and care for the wood properly, before this happens. All wood is subject to these changes.

Edit: Chris- Dude, Purpleheart is not immune at all (trust me). Clamping under a little pressure to remedy a slightcup is no big deal (actually the moisture in the glue may even help equalize the warpage if the cup is on the glued side). However forcing a piece flat that has a significant warp or twist and glueing is BAD, BAD,BAD or extreamly risky down the road.

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right now it is about 15mm; i want to use it for a core between sipo and quilted maple;

i know its not expensive; but thats beside the point; i dont just throw things out if i think theres achance i can save it;

maybe 1mm is a lil over exagerated but the cup/twist is pretty bad;

my humidity is always in check, its stays around 65,but my air cond. is pulling alot of moisture out of the air;more than normal; it wasnt stickered, i usually dont bother with purpleheart/bloodwood stuff like that; i do my walnuts and thin tops

this purpleheart prolly spent most of the time on its side leaning on the shelf

if i had to explain the warp, i'd say(use your imagination) the bottom of the one end is as high as the other ends top;did i explain that right?

im use to 4/4 and 8/4 stock of PH so ive never really seen a twist in it either

thanx guys

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So it is a little over 1/2" thick. It is cupped approx 1mm(1/32"-ish), and the board has twisted so that from corner to corner it is about 1/2" out. The cupping sounds like it is nothing, but thats a bit of twisting going on there. You said it was leaned up against a shelf- so it should have had pretty even air flow. It is odd that it would do that to you if it was fairly stable when you stored it. RH of about 65 is just a little high, but not bad. Oh well, I would try to sticker it under weight and see if you get any improvement. The flatter you can get it the better. Flattening a twisted board is a pain. Good luck with it :D


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  • 4 weeks later...

I'm still fairly new to woodoworking, so this is kind of a dumb question, but what is stickering when you get new wood?

Literally stacking wood with sticks(say 1/4" to 1/2" thick) of wood to space them. This allows the wood to lay flat, and allows air to flow to all sides evenly (this helps to stabalize the wood as it acclimates to your humidity levels). Weight can also be added to help keep the wood flat. It is also a good practice to seal the end grain (with wax, wax paint, shellac or what have you) to slow the transfer of moisture in that area (endgrain realeases and accepts moisture quickly compaired to side grain). Sealing is very important if it will be stored for long periods or during radical changes in humidity.


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what if you seal it in a plastic bag?

Im going to lay a piece on it but I dont want to wax the ends..

Plastic == not so great. Unless you want to do the 'kiln in a rubbish bag' trick (black bin liner, piece of wood, The Sun). And even then you need to let the moisture OUT afterwards. Just get some end sealer, heck, even just latex paint or shellac if that's all you've got, sticker and stack with plenty of air flow. You want the moisture OUT, not kept in, and letting your wood cycle through the seasons (Stored without good humidity control until short-ishly before you actually want to build with it) is a good thing. As long as it's stickered.

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