Results 1 to 15 of 15

Thread: epoxy in knot swelled

  1. #1

    epoxy in knot swelled

    Hi, I filled a knot in a walnut top with total boat epoxy. I waited about a week and then put a coat of boiled linseed oil and then it sat in my shop for a couple of months. I went to take a look at it last night and the epoxy in the knot swelled a bit.

    I'd like to proceed with a coat of shellac and then em8000 from target coating.

    Any idea why the epoxy swelled? Should I worry about it happening again? I have included a pic but I am sure its hard to see.



    IMG_20220613_185106891.jpg

  2. #2
    Join Date
    Aug 2021
    Location
    Redmond, OR
    Posts
    414
    Maybe the board shrunk do to seasonal variations? Maybe the shrunken knot hole made the epoxy bulge even though the epoxy didn't change in size at all?

    Just tossing out the possibility for further discussion, not saying this is what actually happened.

  3. #3
    Quote Originally Posted by Michael Schuch View Post
    Maybe the board shrunk do to seasonal variations? Maybe the shrunken knot hole made the epoxy bulge even though the epoxy didn't change in size at all?

    Just tossing out the possibility for further discussion, not saying this is what actually happened.
    I think you're onto something. I put the epoxy in the knot in early spring when humidity was low. Now we're in the throes of Summer and it's super humid.

    Does that mean I shouldn't sand it down? If this theory is correct and I send it down, it will have a void when the knot goes back to its original size.

  4. #4
    Join Date
    Mar 2010
    Location
    Somewhere in the Land of Lincoln
    Posts
    2,221
    From the little research I did linseed oil acts as a drying agent. If I read it correctly. So maybe it caused the wood to shrink. Also is the epoxy still hard and solid? Some products will react with it. Alchohol for one.

  5. #5
    Join Date
    Nov 2009
    Location
    Peoria, IL
    Posts
    3,021
    Wood swells in the spring and summer, so the knot hole should have gotten wider. How thick was the pour? Deep pores take days to cure and it may not have been fully cured when you sanded it.

  6. #6
    Join Date
    Aug 2021
    Location
    Redmond, OR
    Posts
    414
    I haven't used boat epoxy but the epoxies that I have used have been very stabile as far as keeping its size. That is why I suggested it might be the wood instead of the epoxy.

    I don't know what to advise you as far as sanding it down.

  7. #7
    The wood moved. Even if the shrink happened in the winter, the epoxy may not settle back when the wood later expands. Also it is possible the slab was not dry when the epoxy went in.

    It happened to me as well. If you sand it you will have to sand the wood and refinish as well. I left mine.

  8. #8
    Join Date
    Nov 2006
    Location
    Atlanta
    Posts
    1,203
    Looks like it wasn’t mixed thoroughly. It’s difficult to tell from the pic, looks more like it shrunk which is typical during curing.

    But not afterward, neither is expansion. Your wood moved.

  9. #9
    Join Date
    Apr 2013
    Location
    Okotoks AB
    Posts
    3,398
    Blog Entries
    1
    The wood shrunk. I've never heard of epoxy swelling. Agree with insufficient mixing. Did it all cure solid?

  10. #10
    I think you guys are correct, I don't think I mixed the epoxy well or I didn't have the correct ratio...I did something incorrectly because I just went out and stuck my nail in it and it is not as hard as the other knots that I filled around the same time.

    This was my first time mixing and using epoxy so lesson learned.

    Question is what do I do now? Should I try to dig it out the soft epoxy and put another layer of properly mixed epoxy on top?

  11. #11
    Join Date
    Mar 2010
    Location
    Somewhere in the Land of Lincoln
    Posts
    2,221
    Quote Originally Posted by Julio Vargas View Post
    I think you guys are correct, I don't think I mixed the epoxy well or I didn't have the correct ratio...I did something incorrectly because I just went out and stuck my nail in it and it is not as hard as the other knots that I filled around the same time.

    This was my first time mixing and using epoxy so lesson learned.

    Question is what do I do now? Should I try to dig it out the soft epoxy and put another layer of properly mixed epoxy on top?
    Alcohol will soften it. Whether it will be enough to remove I don't know. For those unfamiliar Total Boat is a brand of epoxy. They do obviously make resins for marine use but also for other applications. Jess Crow Makerpoxy is one of their epoxy products intended for uses like this. Just curious what one you used Julio. As the Makerpoxy is 1:1 ratio and pretty simple.

  12. #12
    Quote Originally Posted by Ronald Blue View Post
    Alcohol will soften it. Whether it will be enough to remove I don't know. For those unfamiliar Total Boat is a brand of epoxy. They do obviously make resins for marine use but also for other applications. Jess Crow Makerpoxy is one of their epoxy products intended for uses like this. Just curious what one you used Julio. As the Makerpoxy is 1:1 ratio and pretty simple.
    I used total boat high performance with their fast hardener.

    All the other knots I filled are good, its just this one. I probably either made a mistake in the ratio for this particular knot or I didn't mix the epoxy and hardener enough for this particular knot.

    I filled a bunch of knots over period of two days so I was mixing up different batches.

  13. #13
    I try not to just fill through knots with epoxy. They never stay flat. I usually rout out the underside of the knot, leaving less than 1/4" of thickness. I then patch it with a matching piece of regular grain material. The resulting veneer of a knot is much less prone to issues related to seasonal movement and the amount of movement is greatly diminished.

  14. #14
    Join Date
    Nov 2021
    Location
    Columbia MO and Howard County MO
    Posts
    865
    My guess is that the Knott "took up" the linseed oil and expanded enough to squeeze the epoxy. Trying to get some data on this theory could be fun. If the epoxy remained soft something went wrong with the glue. I use a carefully placed low watt incandescent light bulb to warm up epoxy that is curing too slow. Epoxy can go bad. Proper mixing and ratio are important.

    The board shrinking is a very real possibility.
    Last edited by Maurice Mcmurry; 06-15-2022 at 8:45 AM. Reason: Re read OP timeline
    Best Regards, Maurice

  15. #15
    Join Date
    Mar 2010
    Location
    Somewhere in the Land of Lincoln
    Posts
    2,221
    Quote Originally Posted by Julio Vargas View Post
    I used total boat high performance with their fast hardener.

    All the other knots I filled are good, its just this one. I probably either made a mistake in the ratio for this particular knot or I didn't mix the epoxy and hardener enough for this particular knot.

    I filled a bunch of knots over period of two days so I was mixing up different batches.
    As I recall when using the Makerpoxy they said to mix for a minimum of 4 minutes. Mix by hand and not with any sort of power tool. That keeps any air infusion to a minimum. If you do much with epoxy then I recommend getting silicon mixing cups. When it dries you can then flex them and the epoxy will come loose.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •