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Subject: Ozone


From: Doug Nishimura <dwnpph>
Date: Sunday, October 10, 1993
I must have missed seeing Pat Smith's posting about ozone.  It was
brought to my attention by someone else on the list.

Ozone may indeed be "stronger than chlorine", but what does that say?
Actually, according to the reduction potentials listed in the 72 ed of
the CRC Handbook of Physics and Chemistry, ozone in acid is much
stronger than chlorine gas, but ozone in a neutral environment is
slightly weaker than chlorine.  However, consider a common chemical that
is much weaker than ozone -- chlorine bleach (like Chlorox).  Now
granted, ozone is not a wet alkaline solution (and therefore is a little
slower to react and less damaging in some ways), but even so, you really
wouldn't want to pour Chlorox on your library collection (even if it was
dry and neutral.)

In general ozone bad for everything. A few years ago, Ilford had a
problem when one night a custodian at one of the research labs decided
that there was a funny smell in the air.  As the story goes, he wanted
to get things taken care of at night so as not to be bothering the
research people.  The building was ozonated (ozonized?) and sure enough
the smell disappeared. The research people were rather perplexed to find
that many black-and-white photographs in the building (including test
materials) were turning orange. They eventually did track down the
problem (which made a good story at the ANSI meetings.)  Of course, the
photographs were turning orange because of colloidal silver formation.
This deterioration had become visible within only a few days of the
ozone being used. (Ack!!) Other materials may be more robust (although
we have found in our pollution chamber that color photographs/hardcopy
prints (i.e. T2D2 prints) are more sensitive to such gases than silver.)
Consider what happens to cotton fabrics with chlorine bleach and it
gives you an idea how oxidants behave with paper.  Proteins such as
gelatin also undergo oxidation.

One of the class demonstrations that I do to show the "accelerated"
effects of oxidants (like ozone) on photographs is to dip a piece of a
print and a negative into dilute Chlorox.  You can watch everything
disappear until you only have a piece of bare film support or paper.
Everything else is either in solution or sitting in the bottom of the
container.  It happens in minutes.

We have also found that synergistic effects are extremely strong so that
ozone with minute quantities of say H2S is extremely aggressive.

I would suggest that you try to find something else to use other than

Good luck.

-Doug Nishimura
Image Permanence Institute

                  Conservation DistList Instance 7:32
                Distributed: Wednesday, October 13, 1993
                        Message Id: cdl-7-32-003
Received on Sunday, 10 October, 1993

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