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Wenge Weirdness

Discussion in 'Luthier's Corner' started by Rob Page, Jan 17, 2021.

  1. wenge-weirdness.jpg I haven't worked with wenge much and this just happened. I split this board to make a couple of fretboards and the inside has these really cool tan streaks through it. At first I was stoked, then I thought, maybe this is some kind of tree disease?

    Mysterious cause the outside surfaces have no sign of it (though the sides did before I split it).

    Anyone seen this before?
  2. Slidlow

    Slidlow Supporting Member

    Apr 15, 2009
    Oshawa, Canada
    First suspicion is the exposed surfaces oxidized over time and evened out the color.
    SlingBlader, pellomoco14 and Rob Page like this.
  3. GMC


    Jan 1, 2006
    Wiltshire, UK
    Wenge, when first cut is bright yellow and it’s saw dust looks like pollen. Soon it oxidises into the familiar dark chocolate brown
    Goatrope and Rob Page like this.
  4. 1958Bassman


    Oct 20, 2007
    Look at the end grain- if it's mostly parallel to the flat surfaces, the lighter color is growth ring.

    Watch out for splinters!
  5. dwizum

    dwizum Supporting Member

    Dec 21, 2018
    Yeah no kidding! Wenge splinters like nothing. And the splinters are painful for days, even after you pull them out.
    Koshchei, eddybuzzard and GMC like this.
  6. And the rash. Like poison oak. Hate working with it at all but it do look purdy when it's all done. Lots of protective gear.
  7. It should darken back up as described above
    Rob Page likes this.
  8. Slidlow

    Slidlow Supporting Member

    Apr 15, 2009
    Oshawa, Canada
    And if it doesn't darken use some "potassium permanganate" in solution to darken it. Old luthier trick.
    FugaziBomb likes this.
  9. I love old luthier tricks! Thanks!!
  10. 1958Bassman


    Oct 20, 2007
    Are you sure that wasn't Potassium Dichromate? It was used for darkening Cherry and other woods (among other applications), but it's very toxic.
    Last edited: Jan 18, 2021
    FugaziBomb likes this.
  11. Slidlow

    Slidlow Supporting Member

    Apr 15, 2009
    Oshawa, Canada
    I'm sure. Google it's use by luthiers and videos will come up.
    FugaziBomb likes this.
  12. Is this a thing? :eyebrow: :cautious:
  13. micguy


    May 17, 2011
    It is also possible that the outsides, like a lot of ebony and rosewood fretboards, were dyed darker, and splitting the board unveiled it's "inner blonde".
  14. Rôckhewer

    Rôckhewer Supporting Member Commercial User

    Feb 28, 2015
    Phoenix, Arizona
    Owner/Builder- RockHewer Custom Guitars LLC
    I've never cut into wenge and found a lighter color than the outside... but I don't doubt the oxidation thing for a second.
    I've seen how fast cocobolo turns from purple to brown.

    I was just going to add... maybe that cut was close to the outside of the tree?
    Wenge has a couple inches of sapwood that's yellow.
    Big B., TerribleTim68 and Rob Page like this.
  15. Big B.

    Big B.

    Dec 31, 2007
    Austin, TX
    Sapwood was gonna be my vote as well. Edpecially since you could see it on the edge of the board. Wenge logs can be quite large and the sapwood is often streaky like that. More than once I've found very annoying sapwood inside boards that looked perfect from the outside. Its could also be something that will oxidize as others have suggested but I haven't personally seen that with wenge. Either way its not abnormal and not a disease or anything like that.
    Rob Page and Beej like this.
  16. 1958Bassman


    Oct 20, 2007
    Never heard of Potassium Permanganate used for coloring wood but we did burn the bottom out of an Aluminum pan during a 7th grade science class when we poured it, made a cone and added Glycerine. Makes a great volcano.
    Rob Page likes this.
  17. 1958Bassman


    Oct 20, 2007
    Walnut sapwood is lighter in color and if it's dried using steam, the wood darkens, coming closer to the color of the heartwood. I would imagine other woods react similarly.
  18. Flying B

    Flying B

    Apr 29, 2018
    It does look like sap wood, but I can't see how you can get a layer of sap wood surrounded by heartwood either side, the sap wood is around the edge of the tree so that's very weird.
    Rob Page likes this.
  19. Slidlow

    Slidlow Supporting Member

    Apr 15, 2009
    Oshawa, Canada
    Hi, It does not color the wood. It is a oxidizer and reacts with the tannin in the wood. As wood ages the tannin reacts with oxygen which causes the darkening over time. This speeds it up.
    Rob Page likes this.
  20. 1958Bassman


    Oct 20, 2007
    Much like Ammonia and Oak or other species, but have you tried to remove the darkened areas? It's used to alter the apparent color- you seem to be looking at this as a chemist, rather than from the position of "I want to use this to darken the wood".

    I have also used Chlorine bleach on Cherry- it works well and is safer than Potassium Dichromate (if used properly).
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    May 11, 2021

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