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Thread: Dealing with sap

  1. #1
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    Dealing with sap

    So I milled up some 3" Douglas fir last weekend for the legs on a new assembly table I'm making, got everything to specs and glued them up Sunday evening. Came home last night and one of the sections has sap oozing out along the grain. Never had to deal with sap unless it was on my car parked under a tree. Any advice? I sure cant sand it off. Was thinking about trying some mineral spirits to clean it off and then some linseed oil or shellac?
    A bus station is where a bus stops. A train station is where a train stops. My desk is a work station.

  2. #2
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    The best solvent I've found for removing sap is turpentine Jeff.
    WoodsShop

  3. #3
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    I’ve always used mineral spirits. The bigger challenge is to stop the oozing. Shellac is probably your best bet- I wouldn’t use linseed oil.
    “Pay no attention to what you cannot control..” Epictetus, 100 A.D.
    It costs nothing to be kind to others

  4. #4
    You can try to heat the wood, to set the sap, then shellac it to seal the surface. But like any soft liquid trapped inside, it may eventually ooze until fully dried over years, so plan on cleaning it off from time to time, and resealing.

    To clean, use mineral spirits. BLO is compatible and unnecessarily thick for this. If you LIKE the look of BLO, that's another story.

  5. #5
    We use a lot of reclaimed lumber. I've seen lumber that was felled 200 years ago that still have wet, gooey pockets of sap like they were felled yesterday. Really not mech tho be done about it. I usually just cut a dutchman and seal the area.

  6. #6
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    Im in the Johnny camp. If the pitch wasnt set (kiln dried) your probably sunk in that it is going to come back at some point regardless. You post says "glued up" which would likely eliminate any type of heat solution in that it will kill the glue and your probably close enough to final dimension that any chaos that will rear its head in some sort of post-heat-treat will foul you.

    Bummer.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  7. #7
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    Quote Originally Posted by Mark Bolton View Post
    Im in the Johnny camp. If the pitch wasnt set (kiln dried) your probably sunk in that it is going to come back at some point regardless. You post says "glued up" which would likely eliminate any type of heat solution in that it will kill the glue and your probably close enough to final dimension that any chaos that will rear its head in some sort of post-heat-treat will foul you.

    Bummer.
    Correct Mark, it is glued up. Funny thing is its "oozing" out of a nice straight section that was milled to 24", I see no voids anywhere but there must be something hidden beneath, it's 3" square stock so there is definitely room for a hidden void. So I was wondering if the "clean it and then seal it" trick would work.
    A bus station is where a bus stops. A train station is where a train stops. My desk is a work station.

  8. #8
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    Quote Originally Posted by Jeff Monson View Post
    Correct Mark, it is glued up. Funny thing is its "oozing" out of a nice straight section that was milled to 24", I see no voids anywhere but there must be something hidden beneath, it's 3" square stock so there is definitely room for a hidden void. So I was wondering if the "clean it and then seal it" trick would work.
    Always worth asking but I cant think of any solution that will seep into the work, mix with the sap, and lock it up. Be interesting to hear of a viable solution. Ive fought this a time or two working with softwoods that didnt see heat treat to set the pitch and now I just dont bother if the pitch hasnt been set.
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  9. #9
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    Sap in softwoods typically crystallizes at 15 degrees below the hottest temperature that it has experienced. That's why you frequently see sap oozing out of rafters in a hot attic, as attic temps can easily hit 140+ in a hot summer.

    Most high production softwood kilns heat treat the lumber to 180F at some point in the drying cycle, so it's not usually a problem. It sounds like you acquired some doug fir that was either air dried or kiln dried in a low temperature kiln.

    You can build a home sterilization chamber to heat the lumber, but since it's already glued up it will probably move/distort.

    160F throughout is usually a good temp to seek. Millwork activities such as planing and face jointing may spot heat the lumber higher than 145F (causing some sap build up on the tooling), but in general your lumber should not ooze sap if heat treated to that temp.

  10. #10
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    And considering pva will fall apart when closing in in on 130 degrees.. yeek
    Sometimes I just want to look at pretty pictures,... Thats when I go to the Turners Forum

  11. #11
    Sometimes you just have to back up and redo and get on with it. Heat treat next time. Make a new part and proceed.

  12. #12
    I've had that happen even on some fine 12/4 fir for big doors. For things that will be stained, I put the stock on a table, and use a piece of scrap from same wood to make a diamond shaped patch. For something I know will be painted ; same
    thing ,but less picky about grain match. For your project ,I would first scrape off the pitch and see what the problem
    looks like.

  13. #13
    I have only had to deal with sap from maple.

    MapleSyrup-650x450.jpg

  14. #14
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    Quote Originally Posted by Bradley Gray View Post
    Sometimes you just have to back up and redo and get on with it. Heat treat next time. Make a new part and proceed.

    +1 I will attempt recoveries of certain things but, my reaction time has gotten pretty short. You could spend many hours futzing around and end up right where you are now. If I were facing this I would just make another one and move on.
    Who knows what stands in front of,
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  15. #15
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    Heating the spot to ambient plus 15 degrees seems doable. That's maybe 115 for a garage shop in ND. A coat of shellac and it's only an assembly table. And it's a lesson for next time.

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