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  1. 1st June 2008, 12:24 PM #1
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    Swifty
    Swifty is offline Senior Member
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    Question An unusual phenomenum...

    Hi all,

    I'm putting together a piece using blackwood. The blackwood is well sesoned and apparently as dry as a bone. I sanded back to 240 and overnight the timber developed unusual dark brown marks along the grain, as seen in the photos. They appear to be damp as well, I can smear them with my fingers.
    Something is happening that I don't understand! It has been very damp though in Perth for the last day, with humidity over 90%. Also, the culprit seems to be boards from a single, light coloured plank of blackwood only, the other lengths are unaffected.
    Just wondering whether this will become a problem after I finish the wood, need I use a sanding sealer prior to puting on the finish (which will be wipe on poly)? Appreciate any comments from anyone who can explain...

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    Swifty
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  3. 1st June 2008, 01:12 PM #2
    BobL
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    Quote Originally Posted by Swifty View Post
    Something is happening that I don't understand! It has been very damp though in Perth for the last day, with humidity over 90%.
    I think you have hit the nail on the head there. This looks like a reaction of freshly exposed little resin grains reabsorbing water from the air and streaking. This should be fine once you seal it. Forum members who work with Blackwood should be able to comment if this is a particular issue with.
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  4. 1st June 2008, 01:20 PM #3
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    As bob said. I have seen it with some other timbers. Let it dry, sand it flush and apply the finish. May have to have the heater going in the shed for a bit.

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    John
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  5. 1st June 2008, 02:34 PM #4
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    Yes, it's not uncommon with blackwood. I reckon it's always good to apply a sanding sealer, which could just be a light coat of wipe-on poly. Just sand the marks of, clean, apply your sealers, light sand again, then finish as normal.
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  6. 1st June 2008, 04:02 PM #5
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    G'Day Swifty,
    I presume this is for the clock,
    What finish are you planning to us on it.
    The spots shouldn't be a problem as you will sand between coats, I use wipe on polly for most of my work and there are 3 - 4 coats each sanded between, or so the wife tells she does.
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