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Thread: Any tips on sealing MDF?

  1. #1
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    Any tips on sealing MDF?

    Iím looking for tips on how to seal the edges of borg bought MDF to achieve a glass smooth paint finish. Iíve heard of mixing yellow glue & water. Are there alternative methods?
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  2. #2
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    I've used lightweight joint compound several times and it seems to work fine. Just smear it on with your finger or flexible plastic spatula, let dry, then sand. Inspect, repeat where needed.

    John

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    "The Danish government believes that if we train 5,000 designers, and produce
    one Hans Wegner, the money is very well spent." - Ole Gjerlov-Knudsen

  4. #4
    +1. Shellac is perfect for this.

  5. #5
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    Iíve tried Zinsser spray on shellac and it never has worked for me, maybe I needed more coats. Iím going to try the joint compound and see if that works on some small signs for my daughters church.
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  6. #6
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    The spray shellac, while handy to have around, has never really been a replacement for Seal Coat in my shop. I use it for many things. A shellac primer like Zinsser BIN may do two jobs at once for you prior to painting.
    "The Danish government believes that if we train 5,000 designers, and produce
    one Hans Wegner, the money is very well spent." - Ole Gjerlov-Knudsen

  7. #7
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    Something that's now on my radar for this kind of thing as well as grain filling on guitar bodies is Z-Poxy.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  8. #8
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    Quote Originally Posted by glenn bradley View Post


    Does shellac really seal the edges?

    John

  9. #9
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    I have used Zinsser's Sealcoat and wipe-on poly.
    Ken

  10. #10
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    I can't answer for Glenn but I've done the same. Shellac sealed the edges but it took multiple coats. Just kept at it until it looked right.

    And the magical BIN primer also worked.
    Don't sweat the petty things and don't pet the sweaty things.

  11. #11
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    Back when I was making painted pedestals all the time, regardless of the material - ply, solid lumber, MDF - my process was the same: assemble with carefully aligned joints, either joint compound or Rock Hard Water Putty, sand, KILZ, paint.
    "Live like no one else, so later, you can LIVE LIKE NO ONE ELSE!"
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  12. #12
    If you are painting, I think it's easier to veneer tape the edges. I haven't seen any in a long time but they used to make a paper tape that gave the edge the same surface as the face. If you are putting a clear finish on I just use number of coats of sealer.

  13. #13
    I use Bondo or a similar type of body filler - the brand is not that critical.
    It works well on plywood too.

    Regards,
    Phil

  14. #14
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    I use shellac for my MDF jigs

  15. #15
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    Quote Originally Posted by Jim Becker View Post
    Something that's now on my radar for this kind of thing as well as grain filling on guitar bodies is Z-Poxy.
    Jim - this is a new one to me. Can you tell us a bit about your experience with Z-Poxy?

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