Seems that not only did the top of the container not seal, but the plastic itself was permeable to oxygen. Or, the solvent in the primer weakened the plastic enough to make it permeable.

I do know paint thinner if stored in many types of plastic containers will eventually disappear. Which may be what happened here.

If I'm on my game, I store oil paints/primers in mason jars with a layer of argon gas on top.

Where does one get argon gas - at a gas supplier where you get tanks of nitrogen, etc.? How do you get the gas into the jar?

No, the plastic itself is permeable to the paint thinner, same as leaving the lid off, but from all sides. Whatever liquid paint was at the center of the dry mass was still good, if you scraped it into a metal or glass container and added paint thinner.

Buy empty quart cans at the paint store, or save glass spaghetti sauce jars, the ones that don't taper are perfect.

Casey

Yep, same place. I bought a tank at the welding store, and got a regulator off of amazon for about half the cost the tank store wanted.And then a piece of vinyl hose hooked to the regulator.

Essentially I just got tired of throwing away product. I'm sure my initial investment has more than saved me in materials than it has cost. It's sort of nice to open an old gallon of oil based product with 2 inches of paint at the bottom that is still fresh and not having to deal with decanting it into a smaller container. Although, I still do that too as well depending on how on my game I am.

You can also vacuum pack latex paint in a bag, then insert the bag in the can. I haven't tried oil since I don't use oil.

You can buy small cans of argon as "Bloxygen". Fabulously expensive on a per liter basis, but cheaper than a tank and regulator if you don't use much of it. With the cost of finishes going up it does pay for itself with the first pint you save from going bad.

So you have a tank, regulator and hose. How do you get the argon into the can? Just slightly lift the lid and blow it in? Is the idea that you are not trying for a complete removal of the air in the can and are just adding some argon?

Would argon work with acrylic latex paint? I once swamped a FoodSaver with cherry juice trying to vacuum pack a quart of cherries, so I am leery of trying that with paint.

Decant your paint into small containers filled to the top, add paint thinner on top, do not stir or shake. With so little air the thinner cannot evaporate, paint stays exactly as when you poured it in. With glass, you can visually check the paint w/o opening.

Casey

just lift the lid, stick the hose in the, and fill it up. I usually count to about 30 seconds. The argon itself is so inexpensive, I'm not concerned with whether ten seconds is enough or 30 seconds is too much.

The above method works as well with using thinner. I just prefer to not to do that since I don't like adding thinner to oil paints. And I don't want to always have to decant. From my experience thinner changes the sheen on oil paints. I prefer penetrol for making it flow better. And there is an oil spar varnish I use, which absolutely will not mix with paint thinner. And there is an interior oil varnish I use that the thinner will not just sit on top, it will mix readily with that resin..

I've tried the bloxygen stuff, but found that the cans really have very little product in them. When my argon tank is empty, I can fill it for less than twenty dollars and have at least 500 dollars worth of argon for what bloxygen charges.

I just make sure I pound the lid on tight, it normally lasts as long as it's going too.