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Sanding varnish-- looks white and uneven

Posted by hellobowser (My Page) on
Mon, Jun 15, 09 at 11:43

The last 2 pieces of furniture that I've sanded down, stained, and varnished have been left with a streaky look.
I've been using fine grit sandpaper to lightly sand the varnish, but I'm not sure what I'm doing wrong. Everything looks great up until the final sand. Does anyone have any tips? Thanks!


Follow-Up Postings:

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RE: Sanding varnish-- looks white and uneven

Varnish can take a long time to cure before it's possible to sand/rub it out properly. Like, weeks. How long did you wait? What grit are you using for the final sanding?


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RE: Sanding varnish-- looks white and uneven

there are other things to keep in mind as well, if that streaky look is white and cloudy, then its probably unabsorbed stain that's been left on the surface of the wood. With most stains you have a fixed period to wipe off anything thats going to be wiped off. usually about fifteen minutes. if you wait any longer than that and apply a topcoat, the unabsorbed stain will try to cure through your clear coat- resulting in the cloudy appearance you're likely seeing now. another factor is if you're using a water based clear coat over that stain. now it's a genral misconception that you cant apply a water based product over an oil based one, or vice versa, you can certainly do it, in fact I can only think of a few exceptions, but if you applied a water based topcoat over that oil based stain before that stain has had a chance to outgass (usually 72 hours) then you may also see some streaks. Also it helps to be specific, these are some general rules, but since I don't know what exactly you used, I couldn;t tell you exactly what to do, any specifics?


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RE: Sanding varnish-- looks white and uneven

"Varnish can take a long time to cure before it's possible to sand/rub it out properly. Like, weeks."

Varnish cures by polymerizing, not just drying out.

If you try to work the surface before it is hardened all the way through it will make a horrible mess of the finish.

The bottom layers are soft and the sanding residue from the harder top layer simply embeds in them.


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