# preserving spar urethane



## drew37 (Jul 19, 2012)

Every Summer when I go to use my Helmsman spar urethane I've noticed it thickens
either due to moisture in the air or because of the warmer temperature ...does anyone know of a way to preserve this finish so I don't have to continue throwing away half containers of my supply and the money I've invested? I have ideas but an already proven technic would save me from the cost of trial & error.


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## Fred Hargis (Apr 28, 2012)

I've tried several things, none of them worked well. I've tried exhaling into the can slowly (CO2 in my breath), I've tried making my own CO2 (baking soda and vinegar in a 1 gallon pitcher, then "pour" the CO2 into the can). I've also tried sucking the air out of the can (using one of those Ziplok vacuum bag pumps and a port from one of the bags). I've not tried Bloxygen (aerosol CO2) and I've not tried filling the can with marbles to raise the lever of the varnish, though some say it works well. Some day I may try putting the whole can into a 1 gallon Ziplok Vacuum Seal bag and suck the air out to see how it works. Until then, about the only thing I've done that helps is either (or both): put wax paper on top of the varnish, and 2.) store it in a refrigerator (small one in the shop). The wax paper is cut out using the can's lid upside down as a pattern and cut it out with a utility knife. This works a lot better on oil based paint than varnish but still seems to help. The refrigerator really slows down the curing but if you put the varnish in with food, it may come out tasting like, well, varnish. Good luck, I hope someone has some better ideas.


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## cabinetman (Jul 5, 2007)

Fred already gave you several things to try. Any canned media that gets used...opened...closed will sustain some evaporation contributing to the "thickening". You may try adding a small amount of mineral spirits. There are better spar urethanes than Helmsman.









 







.


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## Steve Neul (Sep 2, 2011)

I normally keep some different size containers and pour the left over finish in a different can to where it fills to the top. If you are having to break the skim off the top of the varnish it probably needs to be poured through a strainer anyway. The Sherwin Williams store I use sells a variety of sizes of empty cans I keep on hand.


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## drew37 (Jul 19, 2012)

*thanks guys.*

Good ideas...I think I will try the different size containers...along with a small shop refrigerator thats pretty much what I was thinking before hand also I've found where someone has tried enclosing propane in with the urethane to keep it from thickening being that the gas is heavier than air.. sounds likely to work but then I'd be dealing with another bad smell and an igniteable gas. Not sure if I want to take it that far but you never know...thought I would put it out there in case someone else might like the idea. :detective:


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## Fred Hargis (Apr 28, 2012)

I forgot about the propane, I've also tried it and it didn't do any better than the other additives; your mileage might vary. I do know that my cans keep longer when almost full (just a little bit used) than when they are,say, 1/2 empty. Seems to me that supports the different size container approach (or maybe using the marbles to raise the liquid level). I've also seen, but never tried, plastic containers that have a bellows built into their side so you can collapse them to the height of the liquid. At some point the cost of trying to save the varnish exceeds the value of the varnish.


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## Hammer1 (Aug 1, 2010)

Smaller containers with tight fitting lids filled to the top are the way to go, leave no air space in the containers, just make sure you date and label the new containers. And you wondered why the Mrs. saved all those empty jelly jars.


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## beerdog (Mar 13, 2009)

I was just going to post a thread and saw this one. Does spar urethane expire? A friend of mine has some old cans that seem OK that he does not want. I would not use them to seal a boat or anythig critical, but figure I could put them to use on less demanding projects..


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## dougj71 (Jul 31, 2009)

I have tried bloxygen and it does work.


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## Fred Hargis (Apr 28, 2012)

beerdog said:


> I was just going to post a thread and saw this one. Does spar urethane expire? A friend of mine has some old cans that seem OK that he does not want. I would not use them to seal a boat or anythig critical, but figure I could put them to use on less demanding projects..


Unopened varnish can keep for a long time, especially if it's stored in a cool place. The problems occur once it's opened and exposed to oxygen. But if that varnish has been kept, say, in the attic it may be just a thick, gooey, mess.


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## rrich (Jun 24, 2009)

First you need to understand how the lid of a paint can actually seals.

If you look at the inside of the lid, there is a raised berm. If you look at the top of the can there is a depression to fit the berm. It is the part of the berm that is closest to the center of the lid that actually seals the can by coming into contact the smaller circumference of the depression in the can.

So what can cause the can to seal incorrectly?

Do you put nail holes in the bottom of the depression to allow the varnish to drip back into the can? These holes allow air into the can.

Is the depression laden with varnish? This prevents the lid from completely sealing. Use a paper towel to clean the depression immediately after getting varnish into the depression.

There are two other options to storing Helmsman, etc. 

If the depression is clean and dry, then place a plastic shopping bag (HD or Lowe's bags work great.) over the top of the can. Gently depress the center of the bag into the can about 1/2". Now install the lid. I use a rubber mallet to tap the lid into place.

The second method is to transfer the Helmsman to a canning jar. (Mason or Ball brand) Use one with a screw on lid. Make sure that the top of the glass jar is clean and has no varnish on it. The shopping bag here also works well, especially if you intend to open and close the jar multiple times.


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## Billy De (Jul 19, 2009)

Something I`v done like for ever,when sealing the lid
is to tap it home along the lip with a hammer. Turn it up side down leave it for a while then turn it the right way up, finished.:boat:


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## Mike123 (Jul 22, 2014)

*store urethane in plastic bottles*

I came up with this and it seems to work (although I've not tested it over 4 months currently). You take a bunch of different sized plastic soda bottles and then figure out, as close as you can, the volume of what you want to store. You then experiment with water of the same volume to figure out which of your plastic bottles comes the closest to filled when you put your water in. You then pour your (in this case, spar urethane) into the bottle. You then squeeze the bottle until the liquid just starts running out the top then cap it and, presto, you can store it as long as you want. I was worried about oil based urethane possibly dissolving the bottle but, so far (several months) that has not happened. I also successfully store thinned spar urethane and reuse it over and over, pouring it back into the bottle and squeezing all the air out when I'm done. Simple!


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## Steve Neul (Sep 2, 2011)

Mike123 said:


> I came up with this and it seems to work (although I've not tested it over 4 months currently). You take a bunch of different sized plastic soda bottles and then figure out, as close as you can, the volume of what you want to store. You then experiment with water of the same volume to figure out which of your plastic bottles comes the closest to filled when you put your water in. You then pour your (in this case, spar urethane) into the bottle. You then squeeze the bottle until the liquid just starts running out the top then cap it and, presto, you can store it as long as you want. I was worried about oil based urethane possibly dissolving the bottle but, so far (several months) that has not happened. I also successfully store thinned spar urethane and reuse it over and over, pouring it back into the bottle and squeezing all the air out when I'm done. Simple!


Just one question. When it comes time to use the finish how do you stir it?


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## fire65 (Apr 27, 2013)

Stretch plastic, like a garbage bag over the top, hammer the top on and store upside down.


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