Zip lock bags yellowing

Emanuele Marconi <emanuele.marconi<-at->usd<.>edu> writes

>Have you ever had similar experiences with (old or new) polyethylene
>bags yellowing?  I am wondering if this can be caused by a
>plasticizer or any other additive used in the production.

As a polymer chemist in the past and a current chemist keeping up on
various industry practices I can tell you that you'll never know.
There are dozens of possibilities because there are dozens of
additives in these things.  And while one baggie will yellow with
age, another will get sticky, and third will get crisp.  There is no
control over these products and the only consistency you can expect
of any common plastic material is acceptable behavior in the short
term.  And now you have to worry about the "biodegradable" versions
that will not only yellow, they will fall apart--a nice quality if
the baggie is in a landfill, in a collection, not so much.

Monona Rossol, M.S., M.F.A., Industrial Hygienist
President:  Arts, Crafts and Theater Safety, Inc.
Safety Officer: Local USA829, IATSE
181 Thompson St., #23
New York NY 10012
212-777-0062


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