Antifungal/Biocide additive for surface cleaning wall paintings

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.  I would
normally use IMS, but I want to avoid potentially
solubilising/disrupting the varnish.

I've been recommended Metatin as an antifungal agent for adding to
varnishes, but this is now banned by the EU as it is very harmful to
human health and the environment. Can anyone recommend an
alternative?

I'm also concerned about the residue any similar product might
leave. When cleaning with triammonium citrate I would clear any
residue by swabbing afterwards with water. If I added an antifungal
reagent to the cleaning mixture, would clearing with water
effectively remove the residue, or would this also remove the active
antifungal agent and stop it working? It would also be useful to
find a reagent which can be added to non water soluble varnishes and
consolidation media.

Alice Tate-Harte
Collections Conservator (Fine Art)
English Heritage
+44 2088584982


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                  Conservation DistList Instance 24:50
                    Distributed: Monday, May 2, 2011
                       Message Id: cdl-24-50-023
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