I have a partially used can that had a film on top when I opened it after 5-6 months. Took it out stirred and used it. 3 days later opened can and film was back. I was unaware I needed to protect product from air in the can.. do I? Thanks brian
[OP]
Contributor
I have a partially used can that had a film on top when I opened it after 5-6 months. Took it out stirred and used it. 3 days later opened can and film was back. I was unaware I needed to protect product from air in the can.. do I? Thanks brian
Brian
Contributor
Yes, of course. Oil based varnish reacts with oxygen in the air to cure. That air space in a partially used can has enough oxygen to cause the film to form on top of the varnish below. If the level of varnish in the can gets low enough there will be enough air (oxygen) for all the remaining varnish to gel, rendering it worthless.Originally Posted by Brian Runau
Get a can of Bloxygen or some Stop Loss Bags to remove the air/oxygen and your partially used cans of varnish will remain good to the last drop.
John
[OP]
Contributor
Thanks, I do this with waterlox, but did not know to do it arm r seal. Brian
Brian
Contributor
All varnishes behave the same in this regard.
John
Moderator
^^ This. And that's why it's always a "kinda good idea" to only buy enough oil based product for the project at hand as much as possible While smaller containers do generally cost more per unit, that's still less expensive than throwing out half of a larger container if it goes bad. Different products seems to be more susceptible to "going bad" than others, but I prefer the conservative approach here, especially since I rarely used oil based products other than BLO. (for that I use Tried and True which in my experience has a pretty good shelf life, given how little is used for a typical application)
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The most expensive tool is the one you buy "cheaply" and often...
Contributor
I've taken to buying ARS by the gallon and then transferring it into pint glass jars filled to the brim. I've opened some after 2 years and they are as good as new. A friend of mine keeps his True Oil in small jars which he stores in the freezer. He claims you don't even need to displace the air between uses. Apparently, at that temperature the reaction rate with the oxygen in the air is really low.
No matter how you go about it you need to prevent air from reacting with varnish before use and between uses.
John
Moderator
Yes, that can work, John. But I suspect the majority of folks "out there" don't do things like that because they don't know any better. Hence, there's a lot of bad/wasted material on shelves. Hopefully, a lot of folks will see your comment and learn from it!
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The most expensive tool is the one you buy "cheaply" and often...
Moderator
I do this with Waterlox. I decant from the 32oz tins into 4oz glass bottles. I also have product that has lasted years. And anyone who has used Waterlox knows that in a vessel that is less than 60% full, it will gel up in a day or two.
Contributor
Bloxygen has worked well for me in ArmRSeal containers.
I have also pulled off the skin and used the liquid underneath. I guess time will tell if using the stuff under the skin was a good idea, but I have some 4 year old projects that show no problems after doing so.
I'm a huge fan of ArmRSeal. That's probably a bad thing because it prevents me from wanting to try anything else.
Mark McFarlane
Contributor
Mark, if you remove the skin and the product underneath has a low viscosity and pours easily and w/o lumps then it's still OK to use, but if it's thick or gelled and is lumpy when poured it's bad.
John
Contributor
Thanks John, I have experienced both symptoms and discarded when thick , lumpy,...
Mark McFarlane
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