Antifungal/Biocide additive for surface cleaning wall paintings

Alice Tate-Harte <alice.tate-harte [at] english-heritage__org__uk>
writes

>I would like to find a suitable anti-mould or biocide agent to add
>to a surface cleaning mixture (either water or water with a
>chelating agent such as triammonium citrate).
>
>I will be surface cleaning some 19th century oil(?) paintings on
>canvas, stuck to a chapel wall which have been varnished. The
>paintings have mildew and mould growth so I would like to add
>something to the cleaning mixture, or apply something after surface
>cleaning to prevent further mould growth in the future. ...

As a start I'd like to say that it is usually best to put as few
chemicals onto art as possible as we do hardly know how they react
when ageing. With this in mind a first "treatment", which has helped
in various occasions all over the world, is air movement. Mildew and
mold like a stable environment, air movement is something that they
absolutely don't like. It doesn't have to be fresh air, just the air
around them is fine. If you keep venting the piece of art for a
couple of days periodically, they will die off.

Second is, that mildew and mold are in some way an expression of
changes in the environmental setting, meaning if they haven't "been
there forever", then something changed. It may be a change in staff:
The last guy always opened the window for half an hour daily, the
new guy doesn't, or something similar. Or, a change in the buildings
structure as of a current renovation. A new paint has been applied
to the walls that seals of the surface and moisture exchange is
blocked. Maybe it's a new varnish on the painting itself that
nurtures the mildew just fine. There are literally hundreds of
causes that can be determined very easy without using any chemicals
at all and maybe can be changed back or altered to make the mold go
away. One essential thing is to talk to the people using the
building, starting from cleaning personnel and janitor to the
reverend whether something changed, if it is not obvious.

As a sanitizer: the easiest thing to apply and the least harmful for
paintings and people is a mixture of isopropanol (70 vol-%) and pure
water (30 vol-percent).

I'd recommend before asking for the hard stuff to try it without
chemicals or with the least powerful ones.

All information come from a class Dr. Thomas Warscheid held at the
Technical University Munich. Dr. Warscheid is a microbiologist who
does a lot of research on mold, mildew and bacteria in and on art
and is very successful with "harmless" methods as he has the proper
understanding of how these organisms live. Maybe you want to contact
him, if you want to try this approach and ask for some further
advice.

Alex Grillparzer
Student, Chair in Restoration, Technology of Arts and Science of
    Conservation (Prof. Emmerling)
Technical University Munich, Germany


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                  Conservation DistList Instance 24:51
                  Distributed: Thursday, May 12, 2011
                       Message Id: cdl-24-51-005
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