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Thread: finish bubbles

  1. #1
    Join Date
    Dec 2013
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    omaha, ne
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    7

    Default finish bubbles

    I am using Minwax Helmsman spar urethane and have a lot of some bubbles in the finish of wood windows and window frames. How do I prevent this? I use a natural bristle brush, clean the surface with mineral spirits, put 1 light coat of urethane on, wait 48 hours, wet sand with 220 grit or extra fine sanding sponge, allow it to dry, wipe down with mineral spirits, apply urethane, wait 1 day, sand, spirits, and last light coat.

  2. #2
    Join Date
    Aug 2007
    Posts
    7,050

    Default Re: finish bubbles

    Sorry to say, this is the way it is with Minwax top coats. Minwax stains are great, it is their finish coats that are complete garbage. No amount of good tools or good technique can compensate. I would suggest sanding out the bubbles and switching to McKloskies polyurethane. General Finishes (brand name ) makes good quality top coats as well. If you switch finishes, do a test in an inconspicuous spot to make sure there won't be any incompatibility issues with the two top coat brands. This isn't usually a problem, but it's always best to play it safe and test first, the last thing you want to do is have to strip/sand an alligatored finish.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  3. #3
    Join Date
    Aug 2007
    Location
    Maryland
    Posts
    1,586

    Default Re: finish bubbles

    Unlike James Bond's martini, any varnish should be stirred not shaken. Small bubbles will become suspended and take a long time to dissipate.
    In addition even scr-aping the brush too hard on the can to get rid of excess varnish can cause bubbles to form. Better to tap the brush gently on the side of the can.
    I'm not familiar with minwax urethane, but I'd take spruce's assessment and try another.

  4. #4
    Join Date
    Dec 2013
    Location
    omaha, ne
    Posts
    7

    Default Re: finish bubbles

    Quote Originally Posted by A. Spruce View Post
    Sorry to say, this is the way it is with Minwax top coats. Minwax stains are great, it is their finish coats that are complete garbage. No amount of good tools or good technique can compensate. I would suggest sanding out the bubbles and switching to McKloskies polyurethane. General Finishes (brand name ) makes good quality top coats as well. If you switch finishes, do a test in an inconspicuous spot to make sure there won't be any incompatibility issues with the two top coat brands. This isn't usually a problem, but it's always best to play it safe and test first, the last thing you want to do is have to strip/sand an alligatored finish.

    yeah, I will try one of those, test it and get at it again, but if it looks better than this I will be so happy - thanks

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