Shelf Life of Aluminum Cans

Say I buy a can of Mountain Dew, with a Star Wars character on the side. If I never open the can, and it just sits on the shelf in my room, how long should I expect it to last? Do any of the ingredients of soda react at all with aluminum?

(My cousin is trying to assemble the whole collection. He claims that the cans should be empty, because over time, the soda will eat holes through the aluminum. I say he should leave them full, because the cans are less subject to unsightly crinklage that way.)

I’m not a warlock.
I’m a witch with a Y chromosome.

Soda cans are coated on the inside with a type of plastic judged safe for food use.

When I worked for the local Coca-Cola bottler, I was told the useful shelf life (the period in which the product would taste the best) was 60 days; after that time there was a deterioration in taste/quality.

As to what causes that deterioration, they didn’t say and I didn’t ask. Could have been the plastic migrating into the soda; could have been just the fact that Coca-Cola gets stale after a while. It doesn’t age well; it’s not like wine.

your humble TubaDiva
“Bring me a Coca-Cola, vintage 7/31/99”

PS Oops, hit the button too soon.

I’d leave the can as is. I don’t think it’ll leak. Besides, if you open it, your Mom will think you’re just a slob and throw it out.

your humble TubaDiva
“My collection of can tabs! GONE! MOMMMM!”

Don’t leavethe full cans near a heat source or in the sun. the sun will fade the printing any way. Have you ever seen a coke that has been left in a car a few months? “Don’t touch it! It’s about to blow!” Over time (several years) the carbonation will leak out. the plastic may completly disentegrate and the acids will oxidize the aluminum. A neat thing about Al is that when it oxidizes, it forms a layer of aluminum oxide which acts as a protective coating. The only cans I collect are beer cans and a full can don’t last very long around here.

Even though aluminum cans looks like their sealed tight to our eyes, they still have tiny holes in them. These are enough that, given enough time, the CO2 in the soda will escape and leave you with flat Coke/Dr. Pepper/Mountain Dew.

You also run the risk of anaerobic bacteria wreaking havoc on the contents. But I am pretty certain that soad eating holes in the can won’t happen.

Also, if the cans get hot, the acid in the soda can react with the can itself and the resulting chemicals can mess you up a bit. I had a friend who’s father had to drop out of flight school along with a few other guys back in the '60’s because of this. They left out cans of Coke in the sun for a few hours as they did their excersizes and work, and later on started having nasty headaches and vision problems. Bad enough to make them have to leave flight school. This might not be the case anymore if the alloys used to make the cans have changed though.

>>Being Chaotic Evil means never having to say your sorry…unless the other guy is bigger than you.<<

—The dragon observes

I have a Coke can (un-opened) that I got during the 1984 Summer Olympics. It has been sitting on a shelf (with other stupid little doo-dads that I’ve collected) for years. I do notice, however, that the can is still very “stiff” (it doesn’t give at all when I try to squeeze it’s sides). I would have thought that if the CO2 was leaking out, that the pressure inside would not be strong enough to keep me from squeezing it. But the pressure is strong enough. After almost 16 years, it doesn’t seem to have lost much CO2. This was also back when they used real sugar, not sucrose/fructose/corn syrup/etc. that they use now. Maybe that makes some kind of difference.

Certain metals form a protective oxide film such as stainless steel, titanium, and copper this film acts as a barrier to the electrolyte. The corrosion products of these metals adhere tightly to the metal. The corrosion products of aluminum do not adhere tightly to the metal and does not form a protective oxide film

The american people are very generous people and will forgive almost any weakness, with the possible exception of stupidity.—Will Rogers