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Thread: Fixing small defect in poly finish

  1. #1

    Fixing small defect in poly finish

    Morning All,

    After filling all knots with epoxy and sanding down to final finish I found 2 small tight knots with a gap about 1/4" long X 1/32" wide. Hard to tell the depth of such a narrow defect but it seems like it could be deeper than 1/8". Hindsight being 20/20 I should have addressed it at that point.

    I've now put on 8 coats of oil based wipe on poly (miniwax brand) and the table looks great but these defect still exists; they might be ever so slightly narrower. I had thought that allowing the poly to pool there each coat while finishing the rest of the table would eventually fill it in and level it out but that hasn't been the case.

    I think I'm going to vacuum up the floor real good and do one final coat for good measure but I was hoping someone might have a suggestion of something I could fill this gap with before (or after) applying my final coat. It would be nice to put something in there that won't interfere with my ability to refinish down the road. I was thinking about using wax but it seems like that might cause major problems when/if I try an refinish at a later date. Maybe I just try to touch up this spot w/ wipe on every evening for the next week or two after the table has been put into service?

    I should mention I'm on a tight timeline as my daughters birthday is next week. Normally we would use a sheet of plywood ontop of our existing table to seat some additional guests but I've cut it up to use for jigs, sleds, ect in the process of making this table .

    Colin

    20180923_111516.jpg

  2. #2
    Colin

    The classic method is French polishing the specific defect until it is filled. I have found that this is very tedious, but it does work. The shellac tends to build up around the defect, however, which will show as a "bump" unless you very carefully flatten it with a sharp card scraper. A second approach is to use a burn-in stick (often shellac). I have an electric putty knife sort of thing, but you could use a hotplate or blowtorch to melt the filler. This may also need some cleaning up. Finally, you could mask the top with tape and try dripping shellac or clear nail polish into the defect. Any minor changes in surface appearance (gloss) will disappear when you apply your final coat of finish.

    These all require some skill and should be tried on scrap.

    Frankly, given your time crunch and the fact that you are one coat from being finished, I would let it go. I honestly doubt that it would ever be noticed, or that it would detract from the appearance of a very nice looking table top.

    Doug

  3. #3
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    Matching wood filler such as Timbermate, let it dry for an hour, pencil brush your poly on just the putty for 2 or 3 coats then apply your full final. Leave overnight before final coating. Don't worry about the full cure time between coats. Let it get touch dry. Only multiple coat the filler which is tiny so a pointy pencil brush is required, not a cotton tip. Fix it now and you will have no regrets. Leave it at peril to your peace of mind. It will take an hour's work tops. Cheers

  4. #4
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    A second approach is to use a burn-in stick (often shellac). I have an electric putty knife sort of thing, but you could use a hotplate or blowtorch to melt the filler. This may also need some cleaning up.
    I used a burn-in stick to fix a gouge in a table with a dark finish. It was simple for an unskilled finisher (moi). A light finish might be more challenging, dunno.

  5. #5
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    The challenge with filling now is that you need to use something that polyurethane will stick to...and it doesn't particularly like to stick to itself sometimes it seems. So to my mind, that rules out anything that's wax related. I'd probably try to dribble a little clear epoxy into the gap, and very, very carefully level with a sharp blade before that final coat or two of the finish.
    --

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

  6. #6
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    For this fix I would use those wax filler sticks, after your final coat is thoroughly dried. Same color as the wood or slightly darker. Put a lighter to the wax for a couple seconds and move it back and forth across the gap until it's filled. Wait a few minutes and then buff off the excess with a shop towel. It'll stick to the poly just fine.

  7. #7
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    Shellac based burn in sticks ought to stick to poly, and are available in many colors, including some that are translucent. That would be my choice, Wood filler would be hard to get to a matching sheen.

  8. #8
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    Steve, what about his stated additional final coat of the polyurethane adhering to the filler? That's what I meant by my concern above.
    --

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

  9. #9
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    I think shellac burned in--especially with a 320 grit sanding as you would do between any poly coats unless the manufacturer has a specific burn in window. I would be doubtful that even with a roughened surface that poly would stick to wax. Besides wax filler is really pretty soft, best for nail holes in trim, and not blemishes in surfaces that will be used.

  10. #10
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    Quote Originally Posted by Wayne Lomman View Post
    Matching wood filler such as Timbermate, let it dry for an hour, pencil brush your poly on just the putty for 2 or 3 coats then apply your full final. Leave overnight before final coating. Don't worry about the full cure time between coats. Let it get touch dry. Only multiple coat the filler which is tiny so a pointy pencil brush is required, not a cotton tip. Fix it now and you will have no regrets. Leave it at peril to your peace of mind. It will take an hour's work tops. Cheers
    This is not speculation. It actually works in a cost effective time frame and does not compromise the durability of the finish. Cheers

  11. #11
    Wayne,

    I did not think this was speculation at all. I think it was the best solution, so far at least, to the OP's problem. I tend to be biased against wood fillers in general but I have looked into this product and I have opened my mind.

    It would be a kindness for people who post questions here and receive advice to tell us what they did.

    Doug

  12. #12
    Thank you for all the replies everyone.

    I went with Doug's advice about leaving it be given my time crunch. They are pretty minor defects and I think they will only bother me. It's a family table and I imagine the surface will start to show abuse even with the hard coating I've put on. When I eventually re-finish I can fix the problem at that point.

    Wayne your solution sounds great; If I had seen it a day or two earlier I certainly would have tried it and applied another coat. Given the table needs to be in service on Wednesday I'm concerned if I do the repair and put the final coat on this evening it won't be hard enough in time.

    I like the idea of fixing it with a wax product which would be easy to apply now or a week ror two down the road but I'm worried it would give me problems should I try and refinish at a later date.

    Thanks again for all the input everyone.

    Cheers,

    Colin

  13. #13
    Colin

    That's very good to know. Thanks for the feedback

    Doug

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