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Thread: How to fix polyurethane/varnish drips

  1. #1
    Join Date
    Feb 2007
    Location
    augusta, GA
    Posts
    319

    How to fix polyurethane/varnish drips

    I brushed on a coat of satin poly on a walnut box without any problems and then sanded with 240 grit paper and then brushed a second coat. The second coat dried slowly and several drips formed at the bottom of the vertical sides. I am sure that I can sand these out, but is there an easier/better way to get the "big pieces" off? Perhaps with a sharp chisel or small hand plane?

    Also, how old is too old for polyurethane? This can was opened in Sept 2008, but showed no skinning or turbidity. It seemed to dry too slowly.

    Thanks

  2. #2
    Pick up the latest issue of WOOD magazine. They have an article on fixing this.

    A pro will chime in, and I defer to their advice, but if it were me, I'd use a sharp chisel or razor taking care to not gouge the rest of the surface. Then I'd sand. The marks will disappear under a few more coats.

  3. #3
    Join Date
    Mar 2003
    Location
    Southport, NC
    Posts
    2,943
    The key to repairing blemishes like drips and sags is to let them fully dry and cure. Effectively what you have done is created a very thick film of finish in the blemish spots. These spots will take a full 3-4 weeks to cure completelythrought the whole blemish. It may feel dry but inside will still be very soft. Keep testing it by lightly pressing with your fingernail until it no longer leaves a mark.

    Once it passes the fingernail test you can begin to fix the blemish. I much prefer using a newly sharpened scraper but 220 sandpaper mounted on a flat sanding pad is OK. Work slowly. If you are not getting fine, dry dust, let the blemish cure longer. The objective is to get the blemish flattened to the same level as the surrounding surface. Then sand the blemish with 320 paper and scuff sand the rest of the item. Now you can apply a new coat of finish and you should be OK.

    You might want to consider applying your finish coat using a spray can poly varnish. It is easier than brushing and you are less likely to apply too much. It's a big mistake to attempt to apply too thick a coat of finish.
    Last edited by Howard Acheson; 03-23-2009 at 3:57 PM.
    Howie.........

  4. #4
    Join Date
    Mar 2006
    Location
    Northeast Ohio
    Posts
    320
    Jim,

    I like to wipe on poly. It goes on a little thinner so may need an extra coat or two but have not had trouble with drips. To my eye, it also flattens better.

  5. #5
    Join Date
    Feb 2007
    Location
    augusta, GA
    Posts
    319
    Thanks for the advice guys. I ultimately used a wide sharp chisel and shaved off the drips the next morning. I sanded flat with 320 grit paper on a block, and then put two more coats on the piece, and it turned out fine. I think I'll use wipe on next time!

  6. #6
    sand, then buff with steel wool 000 and reapply lighter coat....best to spray on. Even buy a can off spray on and just do the section with the touchup

  7. #7
    I concur with Howard on the scraper. I wrap some blue tape on each end to begin the repair, then take it off an carefully finish it.

    I have also had good luck burnishing a single edged razor blade into a scraper of sorts by a stopping like motion on some very fine wet or dry emery paper. I knock off the corners with a diamond hone stick and use it like a scraper to remove the raised portion.

    Finish up with rubbing compound or other polishing procedure to match the rest.

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