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post #1 of 17 (permalink) Old 04-08-2013, 10:52 AM Thread Starter
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Default Bubbles

why is it every time I brush poly anything i get air bubbles. I used Polycrylic on a Jewelry box I built I thought maybe the finish had gone bad. I bought a new gallon strained it ans ended up with the same result. So i switched brushes then went to a cheap foam brush and got the best result.
These are my steps
lightly sand all surfaces with 120
Wipe with cheese cloth
stain the wood
apply one coat of finish
sand with 150
apply finish
sand with 220
apply finish
sand with 320
apply finish
end result finish feels like sand paper when I use a White china bristle brush or a hi quality black bristle brush

conclusion poly needs to be sprayed.
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post #2 of 17 (permalink) Old 04-08-2013, 11:28 AM
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Quote:
Originally Posted by timthetooolman View Post
why is it every time I brush poly anything i get air bubbles.
most likely it is because you are over brushing. Try going in just one direction.
It's also possible that you are over stirring or worse, shaking the container to mix.


Also consider using Enduro Pre-Cat 181 with wither the Enduro Sealer or if you like to accent the grain with BLO or any of the oil stains do so but seal the BLO in with a wash coat of Shellac which also serves as a sealer.
It's engineered to be sprayed but I brush it using fine latex grade brushes with fabulous effect. It gives you a fabulous finish that dries dust proof in mere moments and is tough as nails in service with water clean up.

Last edited by CR1; 04-08-2013 at 01:57 PM.
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post #3 of 17 (permalink) Old 04-08-2013, 01:21 PM
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Tim; "... went to a cheap foam brush and got the best result."
And that's the recommended method. Using a brush is asking for trouble. Also watch the airtemp. and temp. of the container itself...if it was stored under cold conditions, bringing it into a warmer room just in time to apply is probably going to cause problems.
Another item; give it overnight to cure before sanding and applying the next coat. It's not that it's not dry to the touch, it's not cured enough to sand. Speaking for myself, I prefer a sanding sponge wrapped with very fine (220 or 320 grit) for taking off the high points...not really sanding so much as levelling to a glass like surface...after it's cured.
Cheers,
-Dan
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post #4 of 17 (permalink) Old 04-09-2013, 07:28 AM
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I had the same problem and finally went with Minwax Wipe-on Poly with much better results. Really like the stuff, but patience between coats is a 'virtue'.
David
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post #5 of 17 (permalink) Old 04-09-2013, 10:47 AM
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I save old used up sandpaper and use it for sanding the first layer of poly and switch to super fine steel wool for sanding the second layer then I apply my finish. You must let it cure for at least 24 hrs before sandings. On larger projects you can follow with floor paste wax and then with lemon oil. It'll be so slick every single time. Good Luck!
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post #6 of 17 (permalink) Old 04-09-2013, 01:18 PM
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Default Bubbles and such

I make toys for my grandkids. Needless to say, they will be abused. Toy cars run into walls and each other. Anyway, i prefer Minwax brush on poly for it's hardness and also for the slight amber color it imparts to the toys. They make a water based version, polycrylic, that won't add color to the finished product. What i've found works best is a foam brush applying as thin a coat as possible. Don't shake the can or wipe the brush on the side of the rim as that will add air bubbles. Apply the finish but brush as little as possible. When the area is covered make one last pass, along the direction of the grain, tipping off the poly. That means running the brush over the poly as lightly as possible to help break up the larger bubbles. The smaller bubbles should disappear as it dries. After it dries, anywhere from 12 - 24 hours, I lightly sand with 320 grit, vacuum the dust and wipe with a clean lint free rag. Then apply the 2nd coat. i alway apply a minimum of 3 coats and as many as 5 for the front and back of the cars.

Unfortunately, in my tiny shop, I don't have a dedicated area to finish my projects. I try to let the dust settle as much as possible before i finish. What also helps with airborne dust is a simple trick using a cardboard box and 4 dowels. I cut the flaps off the box and tape the dowels into each of the 4 corners so, when the box is turned upside down it looks like it's on stilts. the box is big enough to cover the project on all 4 sides but the dowels leave about a 2 inch space around the bottom so there's some air flow. I keep it that way for an hour or two, until a skin forms so no dust will stick, and then remove the box to let the finish cure. I hope this helps.
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post #7 of 17 (permalink) Old 04-09-2013, 02:22 PM
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I go a much simpler route, just this past weekend I finshed-up a new dining room table for our middle daughter. After stain was dry for a couple days, I simply shook the can and used the oldest and cheapest brush that was handy. Bubbles were everywhere and I used an old trick my wife taught me several years ago: pop the thouands of tiny bubbles by very quickly going over the surface with a torch. That stuff is pretty-much self-levelling once the bubbles are out. I never sanded through four coats and now it is as slick as glass. My neighbor was over and telling me what a pain it is to get the bubbles out of polyurethane... He then watched me do this procedure and just stood there amazed!

Otis Guillebeau from Auburn, Georgia - where each project is undertaken in the most efficient and lazy manner that gets the best results.

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post #8 of 17 (permalink) Old 04-09-2013, 06:02 PM
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Nice tip Otis. Will have to try it.

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post #9 of 17 (permalink) Old 04-09-2013, 07:52 PM Thread Starter
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I know not to shake the can but was wiping the brush of excess product on the rim of the can. I do believe I will try the torch method atleast once dont really want to try Pre-Cat in my basement. Thanks for the awesome tips.
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post #10 of 17 (permalink) Old 04-10-2013, 10:33 AM
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"...but was wiping the brush of excess product on the rim of the can"
Indeed, that will definitely work air bubbles into the poly on the brush.
The stuff self-levels very nicely so it's not likely you'll apply too much product with a stroke and a backstroke. I think that's part of the success of foam brushes, and for sure there are cheap garbage ones and better quality ones. The foam doesn't tend to pick up great gobs of poly when loading it and therefore lays it down in a more controlled manner. (That's my story and I'm sticking to it...)
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