Roasting for the first time Purple Heart

Discussion in 'Luthier's Corner' started by thebassbuilder, Oct 21, 2021.

  1. thebassbuilder


    Mar 7, 2012
    Spartanburg SC
    guitar builder, Meyers Guitars
    I tried my first attempt at roasting wood. I had a Purple Heart fingerboard that as been sitting around for probably 10 years now. It was not a bad looking peace but pail compared to what I normally like. So I put it in the oven at 300 degrees. I started off at 30 minutes and could tell a small difference and then tried another 15 minutes and it really started to look better and then went another 15 and now it is beautiful. See pics below and hopefully they come out in order. It now has a luster to it and I have not done anything to it other than roasting. I am starting a bee build and it will have a poplar body and I think I may roast it as well. May do the maple neck blank as well. Let’s just roast it all, lol!

    Attached Files:

  2. Beej


    Feb 10, 2007
    Vancouver Island
    Looks good! :thumbsup: Did you note any dimensional changes? In my roasting, everything tends to shrink in all directions, but then again I'm roasting at a higher temperature for much longer, and it's mostly been raw lumber.
  3. dwizum


    Dec 21, 2018
    Sushi Box FX and thebassbuilder like this.
  4. skycruiser

    skycruiser Supporting Member

    Jan 15, 2019
    Does a short duration roast like this really alter the color of the wood uniformly through the body of the piece? I figured that was a longer term, lower temp process, but I haven't really looked into it. I would be worried about just getting a surface roast, and once you go to shape the piece reveal the inner lighter colored wood.
    TerribleTim68 likes this.
  5. This was my thought too. Especially with purpleheart. It's been my experience in woodturning that the surface color isn't what lies underneath and you quickly get a totally different color as you get down into it.
  6. thebassbuilder


    Mar 7, 2012
    Spartanburg SC
    guitar builder, Meyers Guitars
    I am kind of worried about that but it being 0.25” thick I feel it will be ok.
    skycruiser likes this.
  7. thebassbuilder


    Mar 7, 2012
    Spartanburg SC
    guitar builder, Meyers Guitars
    No changes that I can tell. Looks like everything is staying stable so far. I am sure you doing it from raw is the biggest issue with removing so much moisture so fast. You should try a lower temp but for a longer timeframe. This may allow it to dry with less shrinking or twisting.
  8. Beej


    Feb 10, 2007
    Vancouver Island
    I've done it quite a bit and have a reasonable workflow at this point. It starts at very low temp and goes up incrementally in 20-30 min intervals until 360f, then roast for around 5 hours. I'm starting with raw lumber, but it's well seasoned and not green. It tends to shrink up to 15% in all directions and turns a uniform colour throughout. :thumbsup:

    Here's a roasted black walnut fretboard:
  9. arbiterusa


    Sep 24, 2015
    That is spectacular. What’s the inlay?
    Beej likes this.
  10. Beej


    Feb 10, 2007
    Vancouver Island
    wraub likes this.
  11. Plain Old Barry

    Plain Old Barry Supporting Member

    Mar 1, 2018
    Sand shading maple is also a cool way to color inlays. It's been done for centuries on furniture.

    It's pretty simple to do...
  12. Sushi Box FX

    Sushi Box FX Supporting Member Commercial User

    May 23, 2020
    Chicagoland, USA
    Sushi Box FX, owner
    Well I just read through that entire thread, completely worth it. Thanks for giving me something to drool over.
    ctmullins and Beej like this.
  13. Thumpin6string

    Thumpin6string Supporting Member

    Apr 25, 2013
    Shoals Indiana
    I guess either my laptop or my eyes are not working correctly. I see no difference between all the pictures, but I'm glad you are happy with it.
  14. What physical trait are you hoping to change by roasting purpleheart?
    You want to weaken it and make it less dense?

    Or are looking to change the appearance to more of the oily burn from working on purpleheart with tools?

    I don't at all understand the roasting trend, especially in dense woods if the wood is properly dried.

    Can someone explain the rationale?
    TrustRod and Beej like this.
  15. Beej


    Feb 10, 2007
    Vancouver Island
    For me, the roasting is purely aesthetic. A goal of mine is to use local, found and reclaimed woods, and since I live in North America, there are few choices for dark woods. I started the roasting process to test out whether or not I could get walnut to darken up a bit. It does darken a lot, and also gains instant chatoyance through the grain, greatly enhanced over a unroasted piece. It also gets burnt in the process and so sanding gives it a sheen at much lower grit levels than unroasted. It can get almost shiny just being sanded to 400. It's also more brittle, but no more than say pau ferro. I've used it on several fretboards so far and those necks have performed about the same as a regular walnut fretboard.

    Also, and this is out of character for me... it changes how the piece rings when tapped. The sound goes up in pitch and has more "ping" when tapped. I'm not a proponent of this, however I know many use a method like this to help them select what appear to be more resonant woods. It does change this way though for what it's worth. :D
    dwizum and Flying B like this.
  16. Philip McAdam

    Philip McAdam Supporting Member

    Feb 24, 2021
    Gabriola Island, BC.
    My understanding was that roasting is a two step process. The first shorter roast is up to 212 degrees. The wood is then allowed to have the moisture evaporate out. After that the wood is brought up to 470 degrees and roasted for five hours or more. Of course I could be wrong. Kind regards.
    Beej likes this.
  17. Are you going to leave the board unfinished? I'm sure you're aware of how much darker unfinished purpleheart gets over time. It will be interesting to see if your board also gets darker. Neat project!
  18. RichSnyder

    RichSnyder Columbia, MD Gold Supporting Member

    Jun 19, 2003
    I thought lack of oxygen was a big part of the torrefaction process. Are the boards placed in foil envelopes or something like that to keep the oxygen out?
    Rôckhewer and Beej like this.
  19. Hey Beej,
    thanks for the honest answer on aesthetic choice, I totally get that.

    I suppose the tap test proves something, like making things more dense perhaps?
    Personally for my thinking, tap tone is maybe beneficial for acoustic instrument wood choice, solid body electrics I have serious doubts about it's usefulness.

    Interesting in any case thanks for the info.

    To the OP, I see the board has been sitting around for 10 years, I'd be amazed it would actually dry it out any more.
    Good luck.
    Beej likes this.
  20. Beej


    Feb 10, 2007
    Vancouver Island
    You guys are bang on when it comes to "torrefaction" as developed in Europe with specific goals for improvements in performance for construction. It's a slow roasting process in an oxygen controlled environment so that "burning" is minimized in the roasting process.

    What I'm doing (and what the OP has done) is more akin to burning the wood in an accelerated drying process. The wood definitely oxidizes in this process, but I've found the burning that occurs is on the surface, but not throughout.

    I've compared my own home-roasted maple with commercially torrefied maple and I cannot tell them apart. As I've said, I'm sure there is a difference on a microscopic level, but for our low-load construction purposes in musical instruments, there does not seem to be any significant difference.

    I'm doing it for aesthetic reasons, so I'm sticking to woods that really look more beautiful when roasted. I know this will sound dickish, but I don't use home-roasted maple in my builds, as it looks very similar to cherry, and I have lots of beautiful cherry already. :D
    Philip McAdam, RichSnyder and dwizum like this.
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