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Dimples in varnish

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Forum topic by bygrace posted 12-09-2014 12:51 AM 1003 views 0 times favorited 7 replies Add to Favorites Watch
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bygrace

164 posts in 1431 days


12-09-2014 12:51 AM

I am refinishing an oak table for a friend. It has been stained and given a few coats of Watco oil. I let the last coat of oil dry about 7-8 days before starting the varnish. Each coat has left “dimples”, areas where I have observed the smooth varnish pull away and form a dimple. There are no dimples where the grain is nice and tight, but only where the grain seems to open up. I just put on the fourth coat, hoping they would fill in, but I watched the smooth surface give way as the varnish actually pulled away and left a depression. This is only the second time I have used varnish, the first was on a cherry table and I had no such problems. Any suggestions? Any fixes? Prevention for the future? Thanks in advance.

-- Andy, Waxahachie, Tx.


7 replies so far

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bondogaposis

4026 posts in 1813 days


#1 posted 12-09-2014 02:48 AM

It sounds like silicone contamination. Did you sand it down to bare wood?

-- Bondo Gaposis

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Rick M

7910 posts in 1842 days


#2 posted 12-09-2014 05:39 AM

It sounds like the varnish is sinking into the oak pores. Best way to prevent that is fill the pores before finishing.

-- http://thewoodknack.blogspot.com/

View RRBOU's profile

RRBOU

136 posts in 1754 days


#3 posted 12-09-2014 10:38 AM



It sounds like the varnish is sinking into the oak pores. Best way to prevent that is fill the pores before finishing.

- Rick M.

We have a winner.
The finish is sinking into the pores. Either keep adding layers of finish and sanding back or fill the pores prior to finishing.

-- If guns cause crime all of mine are defective Randy

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bygrace

164 posts in 1431 days


#4 posted 12-09-2014 11:15 AM

Bondogaposis, Yes, I did sand down to bare wood.
Rick and RRBOU, I was wondering if that was the problem, but figured I should ask anyway. Thanks for the help.

-- Andy, Waxahachie, Tx.

View Fred Hargis's profile

Fred Hargis

3933 posts in 1955 days


#5 posted 12-09-2014 12:30 PM

You can fill the pores with the varnish, but it’s a slow process. Give it 3-4 coats, let dry several days (at least, I usually wait 7) sand it back, check for the depressions. If they are still some, repeat the process. I just finished doing this on a WO table top and it took 3 repeats, and 3 weeks.But it works really well, the surface looks like glass. Oh, I should mention: before I started the above I slurry sanded the top with danish oil (twice) to get a jump on the pore filling.

-- Our village hasn't lost it's idiot, he was elected to congress.

View OSU55's profile

OSU55

1056 posts in 1452 days


#6 posted 12-09-2014 04:24 PM

The pores will eventually fill. It is a long, slow process with solvent varnishes if it is used to fill the pores. There are some clear pore fillers that are waterbased but I think would be compatible on top of dry watco and under poly or other varnish, like Crystalac. I much prefer a waterborne poly that can be sprayed for a fully filled finish – film build goes much faster, although curing/shrinking is about the same. The longer you can let the finish sit before final smoothing and polishing the better. 30 days during the summer is minimum for me, add at least a week in winter. Otherwise, imperfections from finish cure/shrinkage start showing through after a month or 2.

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Bluepine38

3341 posts in 2547 days


#7 posted 12-09-2014 04:53 PM

My high school shop teacher had us start with shellac as a starter coat, and while I have upgraded to
Zinsser sealcoat, I still start my finishes this way.

-- As ever, Gus-the 77 yr young apprentice carpenter

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