The Woodturning Forum - Woodturner's Resource - Problem using water bassed Minwax poly

merle ward WR Noob Offline WR Rocks! Posts: 17 DeRidder Louisiana USA Gender:	Problem using water bassed Minwax poly Sep 9^th, 2018 at 3:43pm I'm having a problem with little bubbles forming when I brush poly on my bowls. Tried using a light coat or a heavier coat, but same thing. Thanks, Merle
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Ed Weber WR Administrator WR Patron Offline Posts: 8,998 Wilton California USA Gender:	Re: Problem using water bassed Minwax poly Reply #1 - Sep 9^th, 2018 at 5:19pm What species of wood are you applying it to?
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merle ward WR Noob Offline WR Rocks! Posts: 17 DeRidder Louisiana USA Gender:	Re: Problem using water bassed Minwax poly Reply #2 - Sep 9^th, 2018 at 6:58pm Its mimosa. I looked and it seems the ones turned from mimosa are the most problems. I'm down to about 1/2" or so of poly in the qt can. Maybe its time I need to get a new qt. Merle
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Don Stephan

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Re: Problem using water bassed Minwax poly
Reply #3 - Sep 9^th, 2018 at 7:45pm

A first suggestion would be to apply in the same way to a clean piece of glass or plastic, to see if the bubbles are coming from the wood or brush. If no bubbles on the glass or plastic, I'd try applying in the same way to a scrap piece of maple or cherry, a very smooth wood, that has been prepared in the same way as the mimosa.

Several years ago I finished mimosa with a 50-50 mix of mineral spirits and alkyd varnish, applied with a cloth and immediately wiped dry, with no problems I can recall. But after 5 or so applications the open grain structure was still noticeable.

If the can is almost empty can we assume you've applied to wood in similar fashion with a similar brush in the past with no bubbles?

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merle ward WR Noob Offline WR Rocks! Posts: 17 DeRidder Louisiana USA Gender:	Re: Problem using water bassed Minwax poly Reply #4 - Sep 10^th, 2018 at 11:04am I wonder if part of the problem is the poly has gotten a little contamination after using it right out of the can. I looked at some maple and birch that had a very small amount after three coats. Will be off to Lowes in a bit to get another qt. Thinking part of the problem is the mimosa and part the poly.
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Tom Coghill

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Re: Problem using water bassed Minwax poly
Reply #5 - Sep 10^th, 2018 at 6:15pm

I always thin down my initial coats of water based finishes with 50 % water. After the first couple coats, I apply the other layers 66/33 (dilute 1/3 with water). I find this thinned finish allows the bubbles time to get out of the finish. I also apply the finish with a squeeze bottle (like a squeeze Catsup bottle). I apply the finish and smooth it with a very soft brush (all done on the lathe at low speed).

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merle ward WR Noob Offline WR Rocks! Posts: 17 DeRidder Louisiana USA Gender:	Re: Problem using water bassed Minwax poly Reply #6 - Sep 10^th, 2018 at 7:40pm Tom, what brand wb poly do you use? I can't apply it like you do while on the lathe since these are all winged bowls I'm finishing. Has anyone used Stays Clear wb poly?
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Frank Padden Active Member Offline WR Rocks! Posts: 109 Hudson Massachusetts USA Gender:	Re: Problem using water bassed Minwax poly Reply #7 - Sep 10^th, 2018 at 8:02pm Have you tried applying it with a cloth instead of a brush?
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merle ward WR Noob Offline WR Rocks! Posts: 17 DeRidder Louisiana USA Gender:	Re: Problem using water bassed Minwax poly Reply #8 - Sep 11^th, 2018 at 7:09am Went to Lowes and got a new qt. and will try using a cloth. If I still have a problem, will dilute with water and try again. Will have to wait for better weather as I do finishing outside. Too much dust floating around in my shop.
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Don Stephan WR Addict Offline WR Rocks! Posts: 2,666 Cincinnati, Ohio Ohio USA Gender:	Re: Problem using water bassed Minwax poly Reply #9 - Sep 11^th, 2018 at 8:07am Merle What does customer support for the product have to say about bubbles on some woods?
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Ed Weber

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Re: Problem using water bassed Minwax poly
Reply #10 - Sep 11^th, 2018 at 9:41am

When polyurethanes bubble it's usually due to air being introduced during application. It can sometimes be due to surface contaminants or moisture in the wood. OR It can be caused by the application method. Using the wrong brush or over-working the finish van cause finish issues.
merle ward wrote on Sep 9^th, 2018 at 3:43pm:

I'm having a problem with little bubbles forming when I brush poly on my bowls.

If you're brushing WB poly, you should be using a synthetic bristle finish brush. (not foam)
If you need to thin WB poly, use distilled water.

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merle ward WR Noob Offline WR Rocks! Posts: 17 DeRidder Louisiana USA Gender:	Re: Problem using water bassed Minwax poly Reply #11 - Sep 11^th, 2018 at 4:58pm Don, I didn't go to customer support, I did google it and it seems some aren't happy with it for the same reason. Ed, I'm using a 2" sash brush with soft bristles. I don't have any foam brushes. Thanks for the tip for using distilled water when thinning WB poly. Didn't know it would matter.
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Tom Coghill

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Re: Problem using water bassed Minwax poly
Reply #12 - Sep 12^th, 2018 at 10:50am

I use General Finishes water based finishes. I start with the sealer then change to the satin or gloss finishes after that. I build between 6 and 20 coats (they dry quickly so I can build 10 coats a day if I were to stick to it). I sand between every 3 coats with a wet 600 - making sure I get any grit off the piece before the next coat.

The results are very good, - very durable and nice to feel in your hands Thumbs Up

I apply with a very soft, wide synthetic bristle brush that I find at the craft stores ($5 for 3). I ALWAYS wet the brush with water before using it.

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« Last Edit: Sep 12^th, 2018 at 10:52am by Tom Coghill »

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Ed Weber

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Re: Problem using water bassed Minwax poly
Reply #13 - Sep 12^th, 2018 at 12:55pm

merle ward wrote on Sep 11^th, 2018 at 4:58pm:

Didn't know it would matter.

Anything that's in your water will be in your finish when you thin it.
Distilled water doesn't have any contaminants in it.
Municipal water can have additives, softened water has salt (sodium chloride or potassium chloride) and well water has who knows what depending on where you live.

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merle ward

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Re: Problem using water bassed Minwax poly
Reply #14 - Sep 12^th, 2018 at 9:08pm

Well, I didn't get to do anything to my bowls today. Heard a loud noise this morning, went outside to find dead oak limb sticking in the roof. Spent most of the day repairing the roof.

Tom, where do you get the General Finishes? I've never used a sealer before, so how do you use it? I do like a shiny gloss finish even if some say it looks like plastic. My wife says she likes it too so that settles it. Thanks for the info.

Ed, we are on a rural water system for the house and also have a well that we use to water plants and other outside use. Thanks again for the distilled water tip.

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