Poly + Oil


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Old 02-06-07, 09:08 AM
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Poly + Oil

In an old post someone suggested when using Polyurethanes to add linseed oil to help flow.

"Polyurethanes and oil based primers lack the amount of oil necessary to flow and level nicely"

I'm wondering if this applies to the newer mixturers, which are Poly+Stain...can I add the oil to these as well?

Thanks
 
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Old 02-06-07, 02:56 PM
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Personally I wouldn't add linseed oil to polyurathane. If it is too thick to work properly add a little thinner.

Polyshades is better for changing the color of an already finished piece of wood. Care has to be given when using tinted poly - IT MUST BE APPLIED EVENLY with no lap marks, runs or missed spots. Applying it to raw wood is trickier. I always use stain when coloring fresh wood.
 
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Old 02-06-07, 06:03 PM
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I agree... adding anything to polyuethane can mess up the delicate balance of chemicals making up their "recipe". I've even noticed odd evaporation lines (swirls) when I have added some thinner to the poly to make it easier to spray or brush.
 
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Old 02-07-07, 07:54 AM
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Originally Posted by XSleeper View Post
I've even noticed odd evaporation lines (swirls) when I have added some thinner to the poly to make it easier to spray or brush.

Did you stir it well? While I never thin poly/varnish unnecessarily, I've never noticed any problems caused by thinner - of course maybe I need new glasses
 
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Old 02-07-07, 04:17 PM
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Yes, thanks for the thought. It could have something to do with the Valspar Poly I have been using- it's so thick. When I thin it, it seems to want to separate. That's a good point though, it could be that it just needs to be stirred more often than I was stirring it. Can't recall what the weather was like when this happened (extreme cold or extreme hot) I'm guessing that maybe it was cold (needed to thin it in order to spray) and then as it sat on the wood, the thinner must have wanted to separate. But I'm just hypothesizing.

I've since switched to using SW cab acrylic lacquer for much of my trim. I'm giving it a try to see if it's less of a headache. (even though the smell gives me more headaches).
 
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Old 02-07-07, 06:36 PM
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Originally Posted by XSleeper View Post
(even though the smell gives me more headaches)
Maybe it's time to buy a good respirator.
 
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Old 02-07-07, 07:12 PM
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Like to a gallon of poly what amounts of thinner are we talking about?
 
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Old 02-07-07, 07:26 PM
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You rarely ever want to thin any paint/poly more than 10% Don't thin it any more than is necessary to make it apply well. You can always add thinner but it's kinda hard to take it away.
 
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Old 02-08-07, 03:41 PM
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Okay...would it be better to buy the spray cans of Poly and do it that way?
 
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Old 02-08-07, 04:52 PM
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What to you plan to poly? Spray cans don't have a lot of paint/poly in them. it is also thinned down = don't go very far per can.
 
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Old 02-08-07, 09:59 PM
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I'm doing kitchen cabinents. So then poly, with a good brush should be fine?
 
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Old 02-09-07, 07:17 AM
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Yes use poly in a can with a good natural bristle brush. You may need to thin it SLIGHTLY to make it flow better. You can apply more poly with a brush and spray cans would get mighty expensive real quick. As always, sand and dust between coats.
 
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Old 02-09-07, 08:45 AM
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I'll probably buy 1 gal of poly. Is it best to thin the entire galllon and then pour into smaller container as its used over the course of a week or two?
 
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Old 02-09-07, 11:18 AM
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I'd only thin what I used at the time. Varying temps and humidity can alter the amount the poly needs to be thinned, plus if you over thin you can mix in some of the unthinned to thicken it back up.

I rarely thin varnish/poly with the exception of conventional spray. If/when it's too thick to apply properly, I'll thin.
 
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Old 02-09-07, 11:27 AM
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I guess it needs to be thin enough that any brush lap marks will spread out, before setting. Is the trick when applying poly, after spreading evenl,y go across the surface, with the grain , without lifting the brush, from one end to the other?

Thanks for all the great help. I'm looking foward to this project, just want to have many of the details, which can make or break it, worked out.
 
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Old 02-09-07, 11:41 AM
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While the poly can be applied in any direction it MUST be dressed off in the direction of the grain. Since poly doesn't respond well to over brushing I usually apply it with the direction of the grain.

It is best to lightly drag the brush the entire length of the grain. When that isn't feasable you gently, slowly lift the brush off of the wood towards the end of your brush stroke.

Applying no more pressure on the brush than necessary and keeping a wet edge helps to minimize brush marks. Sanding between coats also helps.
 
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Old 02-09-07, 03:19 PM
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Is it best to thin the Poly with, mineral spirits, turpentine or paint thinner.
 
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Old 02-09-07, 04:42 PM
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Turpentine has priced itself out of use, it did used to be the preferred thinner back when it was less than 20 cents a gal. Paint thinner is prefered but mineral spirits is ok, they're almost the same - paint thinner is just higher quality.
 
 

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