Purpleheart has two major flaws. First, the more heat you apply to it the darker it gets, going from purple to almost black. This is really bad if you're doing any shaping using power sanders.
The second flaw is that purpleheart will loose its color the more you work it. The color of the wood comes about due to this resin that occurs naturally in the wood and how it reacts to air exposure and heat. More exposure = more purple color. So if you sand or plane off material, the wood that you expose underneath will be more of a dullish purple-brown color, which is way less attractive.
So I spent a weekend trying to think my way around this so that I could have a fully radiused and polished fretboard while retaining a deep purple color.
From my experience in making bridges out of this wood, I know that you can bake it in an oven to bring out the color rapidly.
I'm not a dumbass, I know that exposing wood to heat causes it to warp. What I became curious about is 1, how much would it warp and 2, could I control that amount by very slowly increasing the heat. I basically entered into experiment mode (halfheartedly as I was afraid I was about to ruin a fretboard).
I worked the board to a point where it was ready to be fretted. It was slotted and sanded down to 400. I then set it in my oven and began to cook it, moving in extremely small heat increments over time.
Needless to say, the wood was rendered completely useless as I feared it would be. Before I began, I defined the minimum amount of bend or twist that i was willing to accept (basically, what I thought I would be able to counteract with the truss rod without impacting playability and neck life). Once I got the thing out of the oven (having stepped the heat back down to cool just as slowly as I had driven it up to avoid rapid contraction) I knew I was in trouble. The thing wasn't just warped; it had freaking waves in it. The peaks and valleys on this thing were so pronounced that I got seasick just looking at it!
Sighing but not surprised, I walked it out to my garage and pitched it into my recycle bin, offering a silent prayer to the wood gods in apology for ruining such a lovely piece of stock.
Things that I've taken away from this whole fiasco:
1. Don't screw with your neck woods. If you can't achieve the look you want at a stable room temperature and moisture level then the wood is not for you. There is no substitute for perfectly straight timber and anything less must not be tolerated.
2. The optimum heating temperature for intensifying the color of purpleheart appears to be right around the 300 to 350 degree range. Again, don't leave it in too long as it will go black over time.
3. Only bake very small pieces of purpleheart. The more surface area it has the more susceptible it will be to warping. So if you make pup rings, bobbins, control knobs or something equally small out of the stuff you should be okay. The thicker the piece is, the safer it will be to bake. Though small, thin items like pickup rings should be watched very closely as it will likely curl like paper given too long.
4. Any large items made from purpleheart, such as guitar necks, fretboards, or bodies, must be allowed to color naturally over time, which means that you'll need to let them lay around in sunlight (keep them cool and ventilated though) for a good amount of time. Because of this, I would expect anything made with a large amount of purpleheart that is deeply colored to be quite expensive.
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Replies
Wes Yates said:
Ok, so if its warped, make sure you have enough material to do this. Use a hand plane to make one side as flat as possible. That will be the 'back' of the fingerboard. Lightly tack that down to a really flat surface with a few dots of glue. Enought to break free but good enough to hold. Plane the front, Yeah, your wood will get lighter but that's the least of your worries now.
You mentioned you have a spokeshave. Use that to rough out a radius OR get a block ~6" long and ~3" wide. Hollow out a inverse radius (concave) and apply 120 grit 3M Sandblaster paper to it. That's the best I've ever used. Sand the shiznit out of it until you have the radius over the face of the fingerboard. No heat to damage the wood. It will take some time as I remember purpleheart is hard as a brick.
now you have flat, relatively non-warped fingerboard that you can apply to the neck. Bad news -- it will be off color as you mention. Leave it to the elements under cling wrap or plastic (don't want warping humidity). Let the sunshine in. Should darken. Might have to do these way ahead of time.
-WY
It's that exact kind of stuff that you have to try at least once though you know? Everybody is always so damned convinced that they know exactly what they're doing but half the time, most of the stuff that they think they know was told to them by someone else who claimed to be an expert. You can't be afraid to screw up. You learn ten times more from your screw ups than you do your successes.
Mungo Park said:
I have put a purpleheart knife handle in the oven once.
I have also microwaved a block of wood to dry it out, bad news their as well it burnt a black hole in it.
Well it might have a new life as about 50 bridges or something else. Thanks for sharing.
Cheers Ron.
Also, regarding darkening the wood, I couldn't have said it better myself. An extremely light touch and lots of patience!
Mungo Park said:
If you let the wood sit in the sun for a day or two before finishing it will darken evenly.
If to have a warped finger board it might be wort a try to iron it, sometimes you can straighten it out. Yes a clothes iron.
I am thinking the slits for the frets were the demon in this project. it might come back a little with time and ironing might get it the rest of the way, by then it should be nice and purple.
Cheers Ron.
Nathan King said:
I'm assuming that if you seal (tung oil) the wood when it's brown, it won't become purple over time like it would had it been left natural?
Josh Gayou (SmokehouseGuitars)
Let's see some pics!!