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Thread: Spots on maple

  1. #1
    Join Date
    Dec 2011
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    Spots on maple

    The furniture retail store (unfinished) I work for just got a maple topped island from one of our wholesalers and it has several greyish spots on it. There are ten to twenty, smaller than a dime, roundish but irregular. They don't sand out. One in particular is a cluster of about 8. The top has been well sanded by the makers and these spots are somewhat faded but visible and can not be sanded any further.

    I feel like I have seen this type of spot before on maple. Does this description ring a bell to anyone.

  2. #2
    Sounds like "spalted" or "ambrosia" maple? Basically a mild form of decay in the wood.

  3. #3
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    Sounds like moisture damage during the sawing/drying process to me. We see this sort of spot on boards that have surface damage/holes that look like the result of logging and sawing equipment used to lift and move logs. Often they look like crush marks and are regularly spaced. Moisture seems to saturate the wood under and around the defect and becomes a permanent stain - like sticker stain but without the fungus or tannin. No remedy other than cut around them.
    JR

  4. #4
    Post a picture. Soft maple can sometimes have these grey streaks.

  5. #5
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    Not spalting or the typical maple streaks but spots. One person here thought wood stain but it just doesn't look like that to me. J.R., I think you might be on the right tract.
    I'll try to post a picture tomorrow if possible.
    Thanks.

  6. #6
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    Yesterday I would have guessed it was mildew but, just today, I learned that the gray splotching in maple is probably an enzymatic oxydation (chemical) reaction in the wood that occurs when the temperature and humidity are high and there is little air flow. There is no good way to fix it only to prevent it from happening in the first place.

  7. #7
    Hey Yonak!

    Right on. Gray stain. Given that it is a chemical reaction in the wood, it is irreversible. Here is a pic of some on a drawer side.IMG_0549.jpg

  8. #8
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    Quote Originally Posted by Danny Hamsley View Post
    Hey Yonak!
    Right on. Gray stain. Given that it is a chemical reaction in the wood, it is irreversible. Here is a pic of some on a drawer side.
    I should be right. I got it from you.

  9. #9
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    Quote Originally Posted by Danny Hamsley View Post
    Hey Yonak!

    Right on. Gray stain. Given that it is a chemical reaction in the wood, it is irreversible. Here is a pic of some on a drawer side.IMG_0549.jpg
    The coloring and shape is right here, sort of, but much, much smaller. One grouping in particular has about seven spots in a cluster about 4" in diameter, each spot smaller than a dime. Whar are you saying causes the chemical reaction?

  10. #10
    Maple will also stain dark if wet iron is left in contact with the surface.
    Lee Schierer
    USNA- '71
    Captain USN(Ret)

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  11. #11
    John,

    The reaction occurs when the wood is above 40% moisture content, the air temperature is high, and the humidity is high with little air flow. The water that is evaporating between the layers of wood increases the humidity between the drying layers in a stack of stickered lumber if there is insufficient air flow. This high humidity triggers an oxidation reaction in the wood with the sugars stored in the parenchyma cells in the wood forming chemicals that stain the wood an ugly gray color.

  12. #12
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    This is a mineral stain. You will find it often in soft maple lumber.

  13. #13
    Join Date
    Feb 2003
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    The spots that I'm thinking of are not gray - more like several shades darker amber color. They often have tiny surface defects associated with them, though the stain goes deeper than the crack so it can be planed away and still leave a spot.
    JR

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