What is the shelf expectancy of model paint?

Thanks for digging this up....
Has anyone used the "life extenders"? Ive seen available from Micro Mark for enamels and Acrylics?....Supposedly you just shoot or squirt some in before you store it for a prolonged period and it helps keep the shelf life....just curious.

^ bump

A lot of good information worth bringing back up to the top again.

There's a lot of good advice, here, and I'dlike to add some:

The enemies of paint, cured or otherwise, are:

sunlight, particularly UV.
freezing and thawing (this is true for all paints, not just acrylics)
oxygen
excessive heat
incompatible solvents
contaminants.

Absent the results of poor storage practices, covered in previous posts, the shelf life of a paint depends on its formulation. A well fomumlated, modern paint can last for decades if kept in a tightly sealed container, protected from sunlight, oxygen, and excessive heat and cold.

High heat causes polymerization (partial curing) of the liquid resins (binder) in the paint. Cold effectively changes the formulation of the paint (it is actually the warming or thawing afterward that causes the problem).

UV changes the characteristics of the binder molecules, changing the way they interact with the pigment and each other.

Oxygen and incompatible solvents effectively change the formulation, possibly making it less stable.

How can you tell if old paint has gone past its usefulness? Stir it up by hand, initially. Don't use a powered stirer. If portions of the paint stay stringy or lumpy after thorough hand mixing, throw it out. If not, get out the power stirer, and mix it thoroughly, then let it stand overnight, and stir again. It should then be ready to use. It is always wise to strain or filter old paints before use.

Thanks for the support jcarlberg, but I must confess. I too have a rather large, my wife would say "out of control", paint collection. I know that some of it dates back to the late 80's easily.

That feels better.

Darren

Well, on balance I have to agree with darrenbb that if the results are important to you, and you're building a fifty-dollar kit, then three bucks for a new bottle of paint might be a wise investment.

Shelf life expectancy? That's like trying to figure out how ball lightning occurs.
I've had polly scale last anywhere from 2 months to 4 years, sometimes 5 depending.
I still have a polly scale paint from when I first bought it 5 years ago. I also have Gunze fron 4 years ago.
Itr's hard to say how long some paints last. I'm guessing the paint will last practically forever, as long as you properly store the paint.

I'm all too happy to provide such information.

I had no idea about acrylics and freezing temperatures until I studied graphic design and illustration in college.

All acrylics are dead in the water and unsalvageable if they freeze

That's good to know about acrylics and freezing temperatures. So I'm guessing that it would also be good advice not to leave your paints outside in the car when it's freezing cold outside. That's something I'd probably have done without realizing it's not good for the paint - visit the hobby store with a friend, go back to his house for a couple of hours and leave the paints in the car.

Excellent information upnorth! Thank you!

A lot of what governs the life and death of paint, any paint, not just model paint, is how the retailer you bought it from keeps it in their shop displays.

There was a hobby shop that I used to frequent (its long since closed down) that had a rack of Polly S acrylics for as long as I can remember. The rack sat directly in the path of the sun near the front window of the store. The labels on the bottles were faded and the pigment was totally settled out in the bottoms of the bottles and there was a good layer of dust on them as well.

I needed two bottles of a particular FS colour, the shop had a rack of Model Master acrylics towards the back of the shop (out of direct sunlight) but only one bottle of the colour I needed. There was another bottle of that same FS colour in the Polly S rack, so I mindlessly bought it.

What a mistake that was! The Polly S was a fraction of the intensity that the Model Master paint was. It was too much of a difference to say it was the way the two companies put their paints together. It could only have been caused by direct and prolonged sunlight exposure.

Pay attention to how your retailers display their paint (and aftermarket decals for that matter) in their stores. Are they kept in direct sunlight in a window? or are they kept in an area of the shop with a bit more controlled lighting conditions? Are they kept away from both heat and cold air return ducts in the shop?

If the shop you go to keeps the conditions that their paints and decals are displayed in, controled and consistent and doesn't put them in places where they will experience extremes in light and temperature levels, the you'll probably get a product that will last for a while, providing that you give it equally controlled conditions when you get it home.

One final word of advice for those who like acrylics; if you live in an area that has genuine winter with snow and sub zero temperatures for extended lengths of time, DO NOT buy acrylic paints from a shop that keeps them right near an outside window. Acrylic paints are dead and useless once they've been frozen, even if only slightly touched by frost they are still dead. You stand a good chance of wasting your money buying paints kept under such circumstances.

Oh, but we are a thrifty lot! I am reluctant to throw away paint unless it rattles in the jar!

I too have never heard of any kind of shelf life for hobby paint. Here are a few things I take in to consideration when preparing to paint:

1. If it's a big project then a new bottle of paint is the way to go. why risk the finish of something I've spent hundreds of hours on because of a three dollar bottle of paint.

2. The older the paint gets the harder it becomes to get all the pigment stirred up. So you don't have an accurate color match. Every time you thin old paint you alter the ratio of pigment to solvent / carrier. In theory this means you will not get a consistent drying time or finish. The paint may also start to yellow or crack prematurely due to the altered ratios. I'm pretty sure that most manufactures would reccomend disgarding paint after a year or two.

I try to buy paint in small amounts as needed. That way I usually have a fresh supply on hand.

Darren

I have some paint that is 20 years old... some testors and Humbrol cans... and it is all still good. It needs a good stiring, and sometimes a little thinning, but it works like new!

naplak.com/modeling

Clean jar threads and lids are the most important things to get a good shelf life from paints. I have noticed that after there is some air space in the jar (about 1/3), the shelf life gets shorter. I have some Pactra Authentic paints which are about 20 years old, and some Compucolor, about 15 years vintage, but they are starting to goo out.

I'm with the guy who's paint is more than 10 years old. I have some Gunze paints which are 10 years old and they still look Ok.

Thanks for the information!

Keeping the jar and the lid clean is probably the most important thing to do.

Storing the bottle upside down actually sounds like a very good idea. I would have never thought about doing that, but thinking about it makes sense.

That's a good question. One that I've never seen addressed by any of the manufactures.
Personally, I have several bottles of Tamiya paints that are at least 10+ years old that are still good. One of them died not too long ago perhaps the way it was closed.
My bottles of MM's acrylics are too new to determine how long they'll last.
I've heard that some store their bottles upside down to prolong shelf life. It keeps air from coming into the bottle, sort of like the way wine bottles are stored.

I'm not sure what the shelf life for paint is unopened. I'm thinking that it should stay pretty long as long as air isn't getting to it and that the air temp didn't heat the paint in the bottle causing it to dry. I use Humbrol and Model Master paints and have never had a problem with a new/old bottel of paint as long as it was stored properly. After they are opened I try to keep the lid and jar clean to keep the lid from sticking and to keep air out from getting in. A bent cap will let air in to.
I spent a year in Korea and came home to a few dried out or almost dried out bottles of paint. I found most were from not having a good seal. But as far as the paint being good in other bottles. I really didn't have a problem, some I just had to add some thinner to and mix really good. Funny, I have had this one bottel of silver for at least 4 years and it still looks good on modelsand figures.
Happy Modeling,
Pat