Dear Salvacion:

In the old days, chemicals and dyes did not have expiration dates because they
did not expire.  It used to be that chemical compounds were assumed to be
stable unless they were known not to be.  In recent years, the practice of
putting shelf-lives (?shelf-lifes) on everything has crept in, and now
everything is assumed not to be indefinately stable.  Philosophically, of
course, this is true.  In 5 billion years, the sun will expand, engulf the
earth, and nothing will be stable.  Buy a gallon of water from the supermarket,
and you will see it has a shelf-life.  I think what has happened is that
manufacturers are thinking "liability", and acting to limit it.  Thus, they
will test a product after, say 1 year, find it still works, and put a 1 year
shelf-life on it.  With any reasonable inventory control system, they will have
shipped it to a customer long before that, so it is still salable.  Thus,
acting on the modern philosophy, you should throw them all out.

On the other hand, you could try them all to see if they work still.  This will
probably cost you more than throwing them out and ordering new, but, at you
least you resolve YOUR liability issues on this score.  I hate to say it (I'm
from Yorkshire, where we pride ourselves on never throwing anything away; we're
even meaner than the Scots and the Dutch), but the easiest course is to chuck
(sorry, dispose of) the lot.  The only exceptions, I would suggest, are simple
chemicals, such as sodium chloride, and dyes that are no longer reliably
available (such as Alcian Blue).

Good luck,

Adrian Leek.


DeLovino, Salvacion S. wrote:

>         Hello Histonetters:
>
>         What's the usual shelf life of most chemicals and dyes when the
> expiration dates are not indicated on the container? We have a whole lot of
> old chemicals and dyes that we don't know if they're still good or not. Some
> date back to the 60's! Thanks in advance.
>
>         Salvacion S. Delovino