Paint question

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Once opened, does it react with the air that gets inside the can, and thus it's just inevitable that it'll "go bad"?

Have a quart of Rustoleum Rusty Metal Primer that I use for, well, painting over rusty metal. Had it for I dunno, at least 6 years. I noticed at beginning of summer it was now making a hard layer at the top of the can and thought it was from a bad seal (no surprise, it's got all the crustiness) so I dropped into a freezer ziplock baggie.

Having to buy a new quart of paint every 5 years is no biggie, and in the future I'll just make sure to clean out the sealing surface more, but I'm just curious, is this normal and expected? Back when I had a house that needed to be painted every few years, the paint can was fully used up when done or needed the following year. :)
 
With all of the modern technology we have today. Computerized modeling, CAD-CAM, etc. You would think that someone would have come up with a better design for a paint can. Because they sure as hell couldn't come up with one that's much worse.
 
It happens. Here's what I do with oil base primers and paints such as the product you mentioned, when storing cans that were used. The best thing to do is make sure the lid rim and mating surfaces of the paint can are clean.Then take some paint thinner, or mineral spirits and pour in just enough to leave a very thin layer covering the primer or paint. Seal the can and store it on a level surface with the lid up. When you open the can the next time there will be no skin over. All you have to do is mix that little bit of thinner into the product and it will be GTG.

Some people store paint cans upside down, then you end up with that hard layer at the bottom of the can. Not good.
 
I have always put a sheet of plastic kitchen wrap on top of the paint in the can. Put the wrap right on top of the surface of the paint, work the air bubbles out and be sure that it is tight against the can around the circumfrence. Keeps paint fresh for a loooooong time!
 
Once opened, does it react with the air that gets inside the can, and thus it's just inevitable that it'll "go bad"?

Have a quart of Rustoleum Rusty Metal Primer that I use for, well, painting over rusty metal. Had it for I dunno, at least 6 years. I noticed at beginning of summer it was now making a hard layer at the top of the can and thought it was from a bad seal (no surprise, it's got all the crustiness) so I dropped into a freezer ziplock baggie.

Having to buy a new quart of paint every 5 years is no biggie, and in the future I'll just make sure to clean out the sealing surface more, but I'm just curious, is this normal and expected? Back when I had a house that needed to be painted every few years, the paint can was fully used up when done or needed the following year. :)
Yes.

There is a product called “Bloxygen” - http://www.bloxygen.com/

It displaces the air, using inert gases, to preserve wood finishes. Even nearly full finish containers will suffer the degradation you’ve seen.
 
How you open the can is important. Use a paint can opener because a screwdriver can warp the lid. Use a rubber mallet and 2x4 when putting the lid on to prevent the lid from warping. Also use a paint can spout to prevent paint from getting into the rim .
 
All Alkyd Enamel will skin you should see how it skins in a 275 gallon tote.
 
I have some oil based paint, thats went from white to almond white. I assume it was due to age, even with resealed cap.
 
Don't get paint on the rim of the can or carefully clean it all off, and as already mentioned, be careful not to mangle the rim when opening or closing it, or another option after using some is to repackage the remainder into a smaller plastic container that seals well.

At the same time, I wouldn't consider it unreasonable to get new paint every 5 years.
 
How do you use it? Do you squirt a shot in the can, then quick hammer on the lid?
Basically that. Once a year touchups on the car, random jobs, like in spring I wirewheeled the mower deck and slapped a coat on to see if it would make it last longer.
 
I have some oil based paint, thats went from white to almond white. I assume it was due to age, even with resealed cap.
That's because of the VOC laws which forced paint companies to lower VOC in oil based paints. In doing so white oil base paints didn't stay white for very long. Even when painted onto a surface and dried, they'd yellow in a year sometimes less.
 
That's because of the VOC laws which forced paint companies to lower VOC in oil based paints. In doing so white oil base paints didn't stay white for very long. Even when painted onto a surface and dried, they'd yellow in a year sometimes less.
No absolutely not
 
Argon? interesting. I wonder if nitrogen would work—I don’t think I can get that anymore but we have plenty at work.
 
I've opened up years old paint that has basically turned into water. Same with shampoo. Seems it eventually turns into water.
 
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