Poly Storage

[Jim Finn]

What is the secret to storing Poly without gettting that hard film on top of the liquid in the can? Happens when it is about 1/2 full or less. It has been suggested to me to drop stones or marbles into the can to keep liquid level full to the top to assure there is little air in the can. Anyone tried this? Any other suggestions?

[Ellen Benkin]

Bloxygen. You can get it at Rockler. Spray it into the can and it fills the empty space.

[Jim Finn]

Thanks for the info.

[Lee Koepke]

Bloxygen. You can get it at Rockler. Spray it into the can and it fills the empty space.
I wish they'd put a lead weight or something in it ... its hard to justify that kind of money for something that feels empty :D

[Jamie Buxton]

Close the can.

That's the entire secret. That's all you need to do.

Now, when I say close the can, I mean that the lid is sealed as well as it comes from the factory. To do this, clean all the finish out of the gutter where the lid closes. Use the tip of your brush to get most of the fluid out, then use a paper towel. If you do it right, the lid will close flush with the top of the can, just like it did when you bought it. If the top isn't flush, you're not right yet. If you don't clean the fluid out, the lid doesn't seal properly, and the finish starts curing in the can.

I've had half-empty varnish cans go for years, and still be film-free when I open them.

[Tom Giacomo]

I don't like the seal on cans, so I pour my poly into Mason jars with the screw on lid because they seal very good, then I store my jars lid down or upside down, then when you need poly if there is a dried layer it is on the bottom out of the way.

[Scott Holmes]

Closing the can tightly is always a good practice.

HOWEVER

It will NOT prevent the varnish from skinning over. Varnish skins over because it reacts with the oxygen in the trapped air. Oxygen is the catalyst for the varnish to cure.

Bloxygen is an inert gas that displaces the air in the can and thus prevents oxygen from reacting with the varnish.

Some people use CO2, others use Argon from the mig-welding equipment. Others use a piece of plastic wrap floating on the surface to prevent the air from getting to the varnish.

Others will pour a thin layer of mineral spirits over the surface of the remaining varnish to cover the top with MS. This will work for a few weeks as long as the can is not move or bounced around in a vehicle.

[Jamie Buxton]

...
It will NOT prevent the varnish from skinning over. Varnish skins over because it reacts with the oxygen in the trapped air. Oxygen is the catalyst for the varnish to cure..

Like I said in my first post, I have experimental evidence that this works. I've had half-full cans of varnish go for at least a year without developing a skin. I suspect that the little amount of trapped oxygen is not enough to skin over the fluid.