Soda cans

Carrie McNeal <cmcneal<-at->museumofplay<.>org> writes

>I am wondering if anyone has experience storing unopened soda cans.
>We have recently acquired several limited edition Coca-Cola cans and
>are considering the best way to store them and whether the liquid
>should be drained prior to storage. ...

Funny you should ask, I just finished treating one.  Our issue was
perhaps slightly different, but I would consider it similar enough.
We acquired an aluminum soda-type can filled with carbonated mineral
water some time after it was made in 1993.  We collected it because
it commemorated the 3000th hit of Dave Winfield, who at the time was
a member of our local Major League Baseball team, the Minnesota
Twins.  At some point, the can had begun to leak, probably because
of the nature of the water inside and the pressure.  Originally it
would have contained 12 ounces of water, but by the time this was
discovered, only about 7 ounces remained inside.  Near the pull tab
there was some whitish powdery corrosion products, possibly in
addition to some salts from the water inside.  No evidence was found
of water puddling in the vicinity, so I am assuming that at some
point, the pressure inside was released due to corrosion, and then
water slowly evaporated out over a period of years.

The solution I followed was to drill a small hole in the underside
in order to drain the remaining contents.  I used a small tube the
vent air into the can as fluid was being added or removed from the
can.  I rinsed out the interior with water and allowed the can a few
days to dry out.  I am fairly convinced that this type of problem
will eventually occur with almost any aluminum soda over time.  I
think the cause would usually be corrosion due to the water inside,
and also the pressure.  I would think it is probably advisable to
drain the contents before this type of problem arises.

Tom Braun
Senior Objects Conservator
Minnesota Historical Society


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                  Conservation DistList Instance 29:45
                 Distributed: Saturday, April 16, 2016
                       Message Id: cdl-29-45-007
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