From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Tire storage
Date: 15 Dec 1998 17:30:24 GMT

Bill Yoder writes:

> However, given that tires don't get better with age, wasn't the
> question how to prevent a supply of tires from getting worse with
> age?  I'll stand by my sealed bag with dessicant suggestion.  BTW,
> they even make zip-lock bags for tanks (as in M-1 Abrams) designed
> to preserve rubber seals, wiring harnesses, etc. in storage.  Except
> in this case, they throw in several pounds of dessicant before
> sealing them up.

Don't toss any desiccant in there, it only encourages the rubber to
out-gas by absorbing volatile components of the tires.  Desiccant is
merely a substance with an enormously enlarged surface area on which
vapors can condense.  What is generally not recognized, is that
anodizing creates a desiccant surface on aluminum.  This effect is
easily demonstrated in a sealed anodized aluminum container that was
previously exposed to room atmosphere.  A humidity probe will show
that upon heating, humidity increases as the desiccant walls desorb a
large amount of moisture, and other species, adsorbed on the enormous
area of the porous aluminum oxide.  Normally, reduces its relative
humidity in a closed container decreases with increasing temperature
but with desiccant it does the opposite because moisture desorbs from
the enormous surface area.

Jobst Brandt      <jbrandt@hpl.hp.com>