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. ...

In a museum, all containers with liquid contents present a leak
hazard, and must be packaged to contain the leak when it happens.
And I mean when, not if.  Museum are tasked with storing objects in
perpetuity, so containment will eventually fail.  Glass containers
might last 1000 years or more before containment fails, if they are
never dropped or broken.  Metal containers won't last nearly that
long before corrosion perforates them.  Especially metal containers
of acidic aqueous liquids under pressure.

You must consider how historic is the value of the contents in situ?
If the label and the container are the historically interesting
part, and the liquid contents add little value, then you're better
off draining the containers, and avoiding an explosion of Coke all
over your other artefacts.  You can store the contents separately if
you don't want to get rid of them (again storing for leak hazards).
A glass bottle will survive with the liquid contents far longer than
the metal, but you'll have lost the fizz (who knows if fizz survives
for centuries if the container remains unbroken?  Even a microscopic
crack or hole would allow the fizz to offgas over
decades/centuries).  The contents add little display value because
you can't see them when in situ, but they have research value in the
future (1000 years from now inquiring minds may wish to know what
the mysterious historic beverage "Coke" was composed of, and want to
test some original contents?)

The varying methods of draining the containers are:

    Break the seal and empty them conventionally

    Drill a small hole in the bottom and drain the liquid

    Use a fine blade to cut just under the rolled over rim of the
    can and cut the end off.  Using a jig you can get a uniform cut
    that is hidden by the shape of the rim, and you can attach the
    end back on

It would be a good idea to rinse out any residues inside, as that
might enhance corrosion if left.  Other people may have some more
suggestions for emptying cans, but those are the ones I'm familiar
with.  With that information you can then decide how important is it
to keep the contents in place, and proceed from there.

Hope that helps

Valerie Tomlinson
Conservator
Auckland War Memorial Museum
Tamaki Paenga Hira
The Domain
Private Bag 92018
Victoria Street West
Auckland 1142
New Zealand
+64 9 306 7070ext 7304


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                  Conservation DistList Instance 29:45
                 Distributed: Saturday, April 16, 2016
                       Message Id: cdl-29-45-006
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