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I have a wipe on poly question...

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Forum topic by Mark posted 02-21-2011 05:26 PM 1754 views 0 times favorited 21 replies Add to Favorites Watch
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Mark

1801 posts in 2148 days


02-21-2011 05:26 PM

Topic tags/keywords: question finishing

Hey there gang, I have a question in concern with my wipe on poly. When I buy my wipe on poly, due to its small pouring tip on the tin can, I buy a paint can to pour it in but what my question is about is when I am finishing a project and the lid has been open either for too long or just too many times and the poly gets tacky and thicker slowly. So instead of wasting the rest of it can I thin it out at all and get the same results? I hate buying a new can of it every so often when I dont have to.

-- M.K.


21 replies so far

View nailbanger2's profile

nailbanger2

997 posts in 2018 days


#1 posted 02-21-2011 05:30 PM

It seems to me, since wipe on is simply poly cut 50-50 with mineral spirits, that you can thin it out again. I just use regular poly in a gal. can, then mix what I think I need for a job. I have a special coffee can dedicated to wipe on.

I’m curious, why do you get the pre-mixed?

-- Wish I were Norm's Nephew

View CharlieM1958's profile

CharlieM1958

15923 posts in 3093 days


#2 posted 02-21-2011 05:31 PM

Some expert will probably refute me, but here is my guess. Your poly starts getting thick when the solvents start to evaporate out of it. So by adding a little more solvent, you are basically just getting back to where you were. In other words, no problem.

-- Charlie M. "Woodworking - patience = firewood"

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Mark

1801 posts in 2148 days


#3 posted 02-21-2011 05:34 PM

I get the premixed just because when I was introduced to it I stuck with it. I’m not too good at mixing thinners in half the time.

-- M.K.

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Mark

1801 posts in 2148 days


#4 posted 02-21-2011 05:35 PM

so what kind of thinner should I use? mineral? paint thinner?

-- M.K.

View smitty22's profile

smitty22

636 posts in 1821 days


#5 posted 02-21-2011 05:41 PM

Hi Mark, As a good starting point, the product info on the can usually specifies what to use for cleanup, and I’ve always found that works fine for thinning as well.

I use Paint Thinner for poly and varnishes.

Cheers!

-- Smitty

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Mark

1801 posts in 2148 days


#6 posted 02-21-2011 05:42 PM

thx dale :)

-- M.K.

View John Ormsby's profile

John Ormsby

1283 posts in 2611 days


#7 posted 02-21-2011 05:46 PM

Here is the trick to keep your varnishes good for a much longer time. Buy a large bag of small glass marbles. Fill the can with marbles every time you use the poly. This will keep the air to a minimum. You can them just wash the marbles with thinner to clean them when the can is empty and you a ready to use them again.

-- Oldworld, Fair Oaks, Ca

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Mark

1801 posts in 2148 days


#8 posted 02-21-2011 05:52 PM

funky but cool..thx :P

-- M.K.

View Don's profile

Don

510 posts in 2117 days


#9 posted 02-21-2011 06:00 PM

what about one of the collapsing containers from Lee Valley to store it in?

-- -- Don in Ottawa, http://www.donebydon.ca

View Mark's profile

Mark

1801 posts in 2148 days


#10 posted 02-21-2011 06:05 PM

never heard of them :S

-- M.K.

View 747DRVR's profile

747DRVR

199 posts in 2231 days


#11 posted 02-21-2011 06:15 PM

I just want to make sure you are pouring the amount of poly you are going to use in a seperate can.You should never work straight out of the original can.That way the original can is only open during the pouring.

View Scott Bryan's profile

Scott Bryan

27251 posts in 2696 days


#12 posted 02-21-2011 08:12 PM

Mark, once the poly starts to thicken and skins over it is beginning to polymerize and there is nothing you can do to reverse the process since this is a chemical reaction between the urethane resins and oxygen in the air. When my poly gets in this shape I will generally toss it since it is not worth screwing up the finish on project to save a few bucks.

You can’t stop this process but you can slow it down by limiting the headspace over the poly once you open the container or pour it into another can. This can be done by pouring into smaller containers. John’s suggestion is also a good one for limiting the headspace. Another way to help forestall this is to use bloxygen. This is simply a can of argon gas which is heavier than air. Spraying it in the container of poly is supposed to displace the air in the container and thereby slowing any further polymerization of the urethane resins.

I would recommend staying away from a plastic container and use only metal or glass for storage of your poly mixture. And, as always, I usually suggest making your own wiping varnish by cutting poly 50:50 with mineral spirits. This will save you some money since by buying commercial wiping products you are paying a premium price for mineral spirits.

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

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Scott Bryan

27251 posts in 2696 days


#13 posted 02-21-2011 09:01 PM

Mark, as is usual, I occasionally get in a mind set about a topic and forget to think about other angles. It is possible that your poly is thickening due to solvent evaporation and adding more solvent will correct the problem, particularly if the wiping product was formulated with a solvent such as naphtha, which evaporates much quicker than mineral spirits.

But, in general, I have found that once poly begins to thicken and reaches the viscosity of honey, for instance, it has begun to polymerize with oxygen and this process is not reversible. I feel it is better, as I said, to simply toss it and start with fresh poly rather than ruin the finish. For what it is worth, I have found that a wiping poly will last far longer than the concentrate. I have kept wiping mixtures as long as two years without any evidence of skimming or thickening. This is generally enough time for me to use them up (I generally mix it in 2 gallon batches) and mix up a fresh batch.

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

View Steven H's profile

Steven H

1116 posts in 1935 days


#14 posted 02-21-2011 09:26 PM

That is why you pour in a separate container and use that. Don’t work out from the wipe on poly container.

View Mark's profile

Mark

1801 posts in 2148 days


#15 posted 02-22-2011 12:25 AM

thx alot fellas, especially your novel scott ;) lol

-- M.K.

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