Storing Paint

[packers#1]

I recently purchased some Polly Scale paint, but now due to unforeseen circumstances, I've had to push that project back.
However, the paint I received is in really super shape (doesn't seem that much, if any, of the pigment is goo). I'll be thinning the paint for airbrushing with iso alcohol, and this has worked to preserve some of my other paint.
However, I'd like to hear what some of y'all do to store your paint. I know there are some things you can do, but can't remember them because it's been so long and I didn't need to store paint back then.

[Philip H]

turn the bottle over after you cap it tightly.

Or, if you are DKS< flood it with argon then turn it over after you cap it tightly.

[peteski]

I don't like the upside down storage because no matter how well you shake it after long-time stroage, some of the settled pigment will remain in the lid/bottleneck.

I'm very anal about cleaning the jar lip and the lid gasket before closing all of my paint bottles. After I tightly screw the lid back on, I give the bottle a little shake to get the paint to go in the lid. That will seal any possible crevices.  I also use a fine permanent marker to mark the paint level and write down month/year of when I closed the bottle. 

I store all my paints that way and I have 25 years old which are still fully usable.  Is that long enough of a storage for you? 

[pnolan48]

I've stored paints for long periods of time by being careful, along the lines Peteski's methods. But, if there are safer, modern replacements for the old Floquil paints, I now buy new ones in acrylics or safer enamels that don't attack plastics. The old Floquils were quite nasty, and the thinner was nastier still. I bought a gallon of that thinner at an auto paint store in about 1985 for $10 (when the hobby store pint was perhaps $3.49), and the counterman at the store asked me if I really wanted to use the stuff in a spray gun, as even the auto industry had moved on.

Without careful attention to seals and storage, the newer formulations do deteriorate within months, especially as the bottles get empty.

[DKS]

I've found paint stores quite a time as long as the seal is good. Unfortunately the lids on all paint bottles is inadequate for the job (at least not without a lot of fussing), so I replace all of my bottle caps with Polyseal caps. These are thick, hard plastic, with a soft, cone-shaped inner seal. You can get replacement Polyseal caps online from commercial bottle suppliers.

[pnolan48]

I've found the old trick of covering the mouth of the bottle with several layers of plastic wrap helps seal the bottle. Removing the cap after the paint or fumes melt some of the plastic wrap might require pliers, and then some moderately yucky cleanup of melted residue, but the method has worked for me--just remember I started in 1972, err, 1962 with flying model airplanes, err, 1954 with plastic model ships. I'm not sure plastic wrap was popular in 1954 or 1962.

Question: is nitrogen nearly as effective as argon? Nitrogen is the opposite of inert (think of tetra-nitro-triglycerine), with the exception of N^2, I think--my last chemistry class was--gasp!--47 years ago.

[Zox]

Question: is nitrogen nearly as effective as argon? Nitrogen is the opposite of inert (think of tetra-nitro-triglycerine), with the exception of N^2, I think--my last chemistry class was--gasp!--47 years ago.

Nitrogen gas--N₂--is quite inert, about as much so as you'll get short of the noble gases. The reason some other nitrogen compounds are explodey is because nitrogen really wants to get to that N₂ state...

[peteski]

Yes, nitrogen is quite inert. The latest craze is to fill your car tires with nitrogen (google for more info).  It has already been used in aircraft tires for a a long time.

[Jeff AKA St0rm]

I use my Digitrax decoder bags and cut them in to little squares that cover the bottle mouth before I cap them. The decoder bags work better than handy wrap because it is a thicker plastic and will not rip when the cap is screwed on.  I have had no problems with them drying out just put them in the paint shaker and ready to go in 3 min.

[peteski]

I've found paint stores quite a time as long as the seal is good. Unfortunately the lids on all paint bottles is inadequate for the job (at least not without a lot of fussing), so I replace all of my bottle caps with Polyseal caps. These are thick, hard plastic, with a soft, cone-shaped inner seal. You can get replacement Polyseal caps online from commercial bottle suppliers.

Those do work well but they are major pain in the  to clean before closing the bottle (as I always do).

[pnolan48]

Nitrogen gas--N₂--is quite inert, about as much so as you'll get short of the noble gases. The reason some other nitrogen compounds are explodey is because nitrogen really wants to get to that N₂ state...

Nicely put, Zox! N₂ is also cheap!

[packers#1]

Thanks for all the responses guys!
What I wound up doing was thinning the paint, and then painting the lip of the jar lids with some of the original full-strength paint. I should be able to break that bond later. I also have stored the paint jars upside-down, per the suggestions here.

[Hyperion]

Painting the lid seems rather counter-productive.  As I always thought that making sure it was completely clean was the key to a good seal.  But since the applied paint shouldn't have dried bits and other semi-solids on it to prevent a good seal, I guess it doesn't hurt.  Seems like removing the cap could be a pain later though.  I would think just sealing it with a clean lid, and then shaking it would insure that any tiny gaps between the lid and bottle may still exist get filled with paint, without having to fill the entire space up with paint before closing.