Thinning polyurethane to make a wipe-on

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Forum topic by Christopher posted 08-26-2009 12:55 AM 34472 views 0 times favorited 8 replies Add to Favorites Watch
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576 posts in 4160 days

08-26-2009 12:55 AM

Anyone know if I can do this? I really don’t see why I couldn’t but I figured I’d better ask my fellow LJ’s as I am sure someone has tryed this. Would I just use laquer thinner?

8 replies so far

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Scott Bryan

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#1 posted 08-26-2009 12:58 AM

Of course. You could use lacquer thinner to do so but it tends to flash off pretty quickly. I generally use mineral spirits since it is less volatile than lacquer thinner. I generally mix oil base poly and mineral spirits 50:50. You will have to add more coats to build a finish since (1) you are only putting it on at half strength and (2) wiping deposits a thinner coat as opposed to brushing.

-- Challenges are what make life interesting; overcoming them is what makes life meaningful- Joshua Marine

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576 posts in 4160 days

#2 posted 08-26-2009 01:02 AM

Hey Scott! I appreciate your prompt response! I figured that was the case but I needed some reassurance. I will go with mineral spirits then!

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3902 posts in 3937 days

#3 posted 08-26-2009 02:07 AM

Scott you should know this what do they use on furniture you buy like a dining table (light).

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3902 posts in 3937 days

#4 posted 08-26-2009 02:22 AM

Scott I mean the finish (varnish)

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1381 posts in 4367 days

#5 posted 08-26-2009 12:15 PM

Note: Polyurethane is an ingredient not a product.

Wood finishing products that contain polyurethane can vary greatly between brands. The amount of polyurethane actually used is not consistent across all brands. It is not uncommon for finishes that denote “polyurethane” in their label to contain other resins such as alkyds.

Other components, such as oils, flatting agents, levelers and driers can also vary greatly.

I use a polyurethane varnish that is 50% solids and is manufactured with pure oil-based polyurethane. Most consumer brand varnishes contain half that amount of solids and may contain a blend of cheaper ingredients.

If you dilute a consumer brand varnish and an artisan brand varnish with the same amount of mineral spirits you may get different results.

Start your wiping varnish recipe with a blend of about 1 part mineral spirits and 2 parts varnish. Only prepare enough to test and experiment on scrap wood until your technique achieves the results you want. Slightly increase the amount of mineral spirits if the mixture is a little too thick. Decrease the amount of mineral spirits if it is too thin.

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8135 posts in 4007 days

#6 posted 08-26-2009 02:06 PM

You can also add either tung oil or BLO to the recipe. Turpentine can be used instead of mineral spirits and will give you better flow and a higher gloss. The introduction to oils and or turpentine will slow the drying time.

-- My favorite piece is my last one, my best piece is my next one.

View PurpLev's profile


8548 posts in 3888 days

#7 posted 08-26-2009 08:56 PM

I also use mineral spirits to dilute poly oil varnish for wiping applications, and like Barry, I brush the first 1-2 coats in order to create a thick uniformed surface on which you can wipe poly for faster/cleaner additional coats (with no brush strokes)

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Max10's profile


1 post in 3430 days

#8 posted 02-18-2013 02:09 AM

Years ago I read an article by a professional finisher, Jeff Jewitt I think, who recommended a 1:1 mix of naphtha and PU. I tried it and liked it a lot. One of it’s great features is that it dust dries so fast, about two minutes. As a result of the quick dry time is that it greatly minimizes dust imperfections. You’ll have to apply probably six coats to attain is good sheen, but the application is so easy, you might enjoy it. So far as I can tell the finish sets up after a few days to be as hard as PU can be. By the way, if your front wooden door is a bit weathered and needs a coat or two of PU, no need to procrastinate thinking it’ll be a bear to take the door down and finish it in the shop. With this recipe you can finish the door in place and even close the door after twenty minutes after each coat.

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