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Iroquois MkII
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241 Posts
Discussion Starter · #1 ·
If I was making champagne I'd be thrilled. But I'm varnishing...

So I stir the can carefully. No bubbles at all. Dip in the foam brush and apply some varnish to the wood. Bubbles! Tiny little bubbles everywhere!

Maybe they'll disappear by morning, but I doubt it.

What'd I do wrong? Is a foam brush not the thing to use?
 

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994 Posts
No.

Use a very good quality regular bristled brush - badger's hair or the equivalent will produce the best results.

Foam brushes are okay for bottom paint.
 

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Telstar 28
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993 Posts
poor bastage... you're varnishing with a foam brush... Get a good bristle brush at least and save yourself some headaches.. :)
 

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ex-Navy
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224 Posts
Varnish without bubbles

Agree with everyone that you should be using a bristle brush, preferably badger hair.
Also get a clean coffee can, punch a hole on each side near the top of the can and run a wire through the holes. After you load your brush with varnish from the can run each side of the brush gently over the wire. This will remove any bubbles you may have picked up. When you're finished varnishing for the day pour the varnish from the coffee can back into the varnish can.
Another trick, if you're doing multiple day's varnish jobs. At the end of the day load your brush with varnish then suspend it in a jar/can of water so bristles are completely covered. The next day remove the brush and paint out all the varnish on some scrap wood and you're good to go. Saves a lot of time and brush cleaner over cleaning your brush properly at the end of each day. Never tried leaving the brush in water for multiple nights before using it but as long as the brush is really loaded with varnish see no reason why it shouldn't work (within reason)
 

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Okay, here I am the contrarian again, but I varnish with cheap foam brushes and achieve good results.

The trick is to use the "point and tip" method just like when applying nice finish paint.

Apply the varnish in short up and down stokes, then tip it out with long opposing strokes, from the wet edge back to the already finished area. Keep moving quickly to maintain the wet edge.

Don't try to re-use the brushes. Once you're done for the day, dispose of it properly and use a new brush for the next coat.

P.S. Another source of bubbles can be a hot surface. MAke sure you're not varnishing in direct sunlight, and it's preferable to have ambient temps falling rather than rising.
 

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Tartan 37C
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501 Posts
Foam brushes all the way, but I've found some brushes are better than others, I buy them by the box from Jamestown Foam Brushes

Make sure your not applying pressure when you applying the varnish as that will create bubbles.

 

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SaltwaterSuzi/CapnLarry
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609 Posts
John Pollard was spot on in every point he made.

I would add (and I've done this professionally for many years so I know whereof I speak) there are two qualities of foam brushes (that I am aware of). The cheap variety is usually black and is very coarse. It does not hold up well. The better ones are grey and are very fine textured.

You can get an equally good finish with either the better quality foam brush or a good quality badger brush. The badger brush will put down thicker coats with longer brush strokes because it holds more varnish.

However, it is time consuming to clean them. We often superficially clean them and then suspend them in thinner when we're doing a job and have to leave them overnight for several nights in a row. I've actually had mine in thinner for months at a time when we're doing a lot of varnishing - but you have to keep an eye on them and change out the thinner frequently.

BTW the bubbles will usually mostly go away when you 'tip it out'. If you're not in direct sunlight, they will all disappear. If you get 'fisheye' somebody has waxed your varnish or gotten silicon caulk on it. If that happens, remove what you've put on and thoroughly clean the surface - several times with Comet, Ajax or similar and plenty of scrubbing and water.
 

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Last season I made a new leg for the dinette table. After staining it to about the shade I wanted, I finished it with three coats of polyurethane. I used foam brushes throughout. No problem. In addition to the points already made: Don't try to put too much on at once.

I re-used my brushes by using a trick The Admiral discovered: Stick 'em still wet (-ish) in a baggie, seal it up and stick it in the freezer. Don't forget to let it "thaw" (it won't really freeze, per se) before using it again.

Jim
 

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One of None
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8,040 Posts
I've always used cheap foam brushes too, I never wipe the foam brush on the edge of the can. When I do things that really must have a perfect finish I make sure every coat is 100% dry then 220 or 600 grit sand between coats. the final coat/s I often spray on then really buff it out with super fine grits like 1500 and or compound. it takes about a week indoors. id'd never try that kind of results outdoors.
 

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Iroquois MkII
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241 Posts
Discussion Starter · #13 ·
Well I switched to a more expensive brush. And of course, I got bubbles.

During my experimentation I went and used varnish with the expensive brush on a piece of smooth pine. No bubbles at all.

The bubbles seem to be a result of the material the varnish is being applied to, as well as the brush. Brushing on very thickly also seemed to relieve bubbles, but created bumps at the edges of the wood where it pooled and ran down.

So, I sanded bubbles off with 320 grit and did a 2nd coat, still bubbles. But less. And now I'm stopping because I hate varnish.

Next year I'll add the stereo to this bulkhead, I'll see how a 3rd coat performs then... or maybe just buff vigorously... dunno. Stupid hateful little bubbles.
 

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Back to just the Jon boat
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941 Posts
I've actually had mine in thinner for months at a time when we're doing a lot of varnishing - but you have to keep an eye on them and change out the thinner frequently.
Foam?? Tried it once or twice and bought the brush.

I have had my varnish brush suspended in thinner for over 20 years.

I take it out and use it when I need to.

I change or add thinner when I need to.

I don't remember how much it cost but 20+ years ago, in them dollars it was a LOT of money.

Works fine, lasts a long time, very few moving parts!
 
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