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Fingerboards: DONT EVER DO THIS!!!

I was in an experimental mood over the weekend. I had recently purchased a fingerboard blank made from purpleheart. I was most excited to see what a finished neck would look like with this as the color of the wood can be quite striking.

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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Permalink Reply by Nathan King on January 20, 2010 at 11:15am

Good to know. I've got a potential p-heart fingerboard project in the works.

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)

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!
David

Let's see some pics!!

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Permalink Reply by Josh Gayou (SmokehouseGuitars) on January 20, 2010 at 12:01pm

That's an excellent question and I don't have a definite answer. It would certainly retard the process but I don't know if it would halt it outright. Exposure to air (oxidization) is certainly a factor in the process. If you're going to use it for a fretboard, you shouldn't have to worry as you'd only oil the timber and maybe rub on a little beeswax anyway. If you're using the wood for the body or the neck itself, I'd recommend working the wood right until the point where it is ready to finish/seal and then lay it aside until the color has a chance to darken up a bit. I definitely would not use purple heart for a customer that had a hard deadline. It would have to be a "you'll get it when it's ready" kind of a deal.

Nathan King said:

Good to know. I've got a potential p-heart fingerboard project in the works.

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)
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!
David

Let's see some pics!!

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Permalink Reply by Mungo Park on January 20, 2010 at 2:53pm

Sharp tools and a light touch helps to prevent darking the wood.
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.

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Permalink Reply by Josh Gayou (SmokehouseGuitars) on January 20, 2010 at 3:08pm

Good points, but I'm going to stick with my final position that it's never a good idea to expose any wood that you want to remain straight and true to any sort of excessive temperatures.

Also, regarding darkening the wood, I couldn't have said it better myself. An extremely light touch and lots of patience!

Mungo Park said:

Sharp tools and a light touch helps to prevent darking the wood.
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.

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Permalink Reply by Mungo Park on January 20, 2010 at 5:25pm

Yah, I hear Ya, good point.
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.

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Permalink Reply by Josh Gayou (SmokehouseGuitars) on January 20, 2010 at 6:38pm

Oh, wow, man. Microwave!

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:

Yah, I hear Ya, good point.
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.

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Permalink Reply by Wes "I'm Baaaaack" Yates on January 21, 2010 at 1:24pm

Josh, I have an idea (I haven't read the replies, but I'm an idiot). I have not tried this but have contemplated it.

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

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Permalink Reply by Josh Gayou (SmokehouseGuitars) on January 21, 2010 at 1:33pm

Yeah, not an option here. Because I was trying to produce color quickly, the board had already been shaped precisely - there was no extra material to take off at that point. I could have run the piece through my bench plane to get it straight again but I would have ended up with a veneer sheet by the time I was done.

Wes Yates said:

Josh, I have an idea (I haven't read the replies, but I'm an idiot). I have not tried this but have contemplated it.

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