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Polyurethane Varnish

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Forum topic by Kv0nT posted 263 days ago 556 views 0 times favorited 11 replies Add to Favorites Watch
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Kv0nT

79 posts in 723 days


263 days ago

Topic tags/keywords: varnish finishing polyurethane finish table old masters

Okay, so I posted earlier that I was having difficulty finishing a table with poly varnish. I used Old Masters because I have had great success with their stains and lacquer. Unfortunately the polyurethane varnish seems to suck. I am using semi-gloss, and even with over 25% Mineral Spirits to thin, I am still having huge bubble issues. No matter how hard I try I can’t work them out, and they don’t pop out on their own. Upping the MS% and using it as a wipe on poly works fine, but I don’t want to do that for a dining table top that gets constant use.

Does anyone have a suggestion for a high quality semi-gloss polyurethane varnish where bubbles are less of an insurmountable problem?

Thank you in advance.


11 replies so far

View gfadvm's profile

gfadvm

10533 posts in 1286 days


#1 posted 263 days ago

I spray Spar Urethane undiluted and have never seen the “bubble problem”.

Do you shake the poly can to mix it?

What are you applying the poly with?

I’m trying to figure out where your bubbles are coming from- application technique or from the wood?

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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Kv0nT

79 posts in 723 days


#2 posted 263 days ago

lol no I don’t shake. I stir. And I was applying with a staining pad, but I have also tried a foam brush. I don’t have the set up to spray.

View tefinn's profile

tefinn

1199 posts in 1033 days


#3 posted 263 days ago

Use a pure bristle brush. Never use a pad or foam with poly. You can also use a polyester brush, but you’ll get better results with the natural bristles.

-- Tom Finnigan - Measures? We don't need no stinking measures! - Hmm, maybe thats why my project pieces don't fit.

View gfadvm's profile

gfadvm

10533 posts in 1286 days


#4 posted 263 days ago

I agree with Tom. Foam and those pads put bubbles in your finish.
I have wiped on up to 22 coats for a table top. Time consuming but no bubbles!

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View pintodeluxe's profile

pintodeluxe

3261 posts in 1409 days


#5 posted 263 days ago

I spray all my tables with pre-catalyzed lacquer. They have held up well to 5 years of daily family dining. That is with two coats, which you can finish in an afternoon. Spraying the finish will solve the bubble problem. It is hard to get a good finish with a brush, but almost effortless with a basic gravity feed HVLP gun. I have sprayed poly too, also with excellent results. I only use poly for exterior use though.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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tefinn

1199 posts in 1033 days


#6 posted 263 days ago

Pinto, what brand lacquer do you use?

-- Tom Finnigan - Measures? We don't need no stinking measures! - Hmm, maybe thats why my project pieces don't fit.

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pintodeluxe

3261 posts in 1409 days


#7 posted 263 days ago

I have used Magnalac, Valspar, and Sherwin Williams and they all work great. Thin 10% with lacquer thinner for best atomization.
For poly I use Deft brand.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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tefinn

1199 posts in 1033 days


#8 posted 263 days ago

Thanks Pinto! The Deft spray can lacquer’s getting very hard to find in my area as well as the gallons. I use spray cans on most of my smaller projects, on the larger stuff I use the HVLP. The HVLP is a pain to set up and clean for one small box or such . I’m thinking of getting a detail sprayer or an air brush and using that for the small stuff, but I’m looking for another brand lacquer that’s readily available so I can use it in the HVLP also.

-- Tom Finnigan - Measures? We don't need no stinking measures! - Hmm, maybe thats why my project pieces don't fit.

View Picken5's profile

Picken5

117 posts in 1288 days


#9 posted 263 days ago

When I’ve used poly, it’s usually been regular ole MinWax brand I’ve picked up at my local big box store. I don’t shake the can, but I do stir it thoroughly being careful not stir too rigorously. I’ve had very good results using foam brushes on flat surfaces such as table tops. And I don’t thin at all. I generally apply by brushing slowly with a single stroke — only stopping to reload the foam brush and continuing the stroke. I’ve also found that brushing over someplace I’ve missed can be a problem if the poly has started to set-up at all. So it’s important to watch the coverage carefully. I’ll usually see some bubbles immediately after applying the poly this way, but the go away well before it dries. And the first coat always needs to a light sanding after it’s dry. I apply the second coat the same way as the first. For me. foam brushes are a bit tricky on vertical surfaces. It’s hard to avoid loading the foam brush too heavily and I sometimes get runs that need fixing. But on horizontal surfaces, foam works great for me.

-- Howard - "Time spent making sawdust is not deducted from one's lifetime." - old Scottish proverb

View Kv0nT's profile

Kv0nT

79 posts in 723 days


#10 posted 263 days ago

Thanks for all the advice. I am going to try doing a sealer coat of 50/50 poly/thinner wiped down. Then I’ll try the narural bristle brush for another 3 coats. I can always wipe it down with ms if the bubbles in this brand still give me lip.

View Lee Barker's profile

Lee Barker

2163 posts in 1447 days


#11 posted 263 days ago

I think the brush is the main culprit here. I highly recommend investing in a good varnish brush, learning to clean it, and delighting in the quality work it permits you to perform.

Go to a paint store that sells to professionals—not a paint department—and check out what they have. You will get what you pay for. If the price tag seems too large, ponder that you’re buying a tool that can last as long as you do.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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