Mold on paintings

Charlene Muscat <charlene_muscat [at] hotmail__com> writes

>I am a post graduate working in the conservation-restoration sector
>here in Malta.  I came across this 20th century painting that is
>infested by mold. On removal of the very thin recent varnish layer
>the mold can be seen rooted in all the paint structure (probably due
>to organic nature of the black pigment used by the artist--a
>recurrent problem found on the black pigment in his works ). I am
>removing the mold mechanically by scalpel under UV light and using
>ethanol after to 'kill it'. Except from the usual RH/T control in
>this case, I would like to ask if anyone knows of any
>material/treatment that can prevent regrowth of mould (for example
>anything that can be added to the varnish maybe). Note that this
>painting is not very old canvas and pigment used are by their nature
>very sensitive.

"Mold is everywhere", they say--even in space.

The fact that we do not see it with the naked eye most of the time
is that it only comes alive when:

    *   The relative humidity raises above 55%
    *   The temperature is around 20 deg. C
    *   and preferably in darkness

These are the perfect conditions under which mold flourishes.

To get rid of it:

    *   Create a controllable environment
    *   Get the humidity below 55%,
    *   Keep it relatively cool
    *   Switch on the light

The introduction of thymol or mothballs isn't a bad idea either.
They emit fungus killing properties best in a ceramic dish under a
light bulb.

Ethanol and killing the fungus: I've made test and alcohol seems to
make mold go completely crazy and actually furthers growth within
the long term. Genuine turpentine--gently applied--however kills it.

I treated a large collection in the early nineties here in Cape Town
And there was no re-growth ever since

Varnish and additives: Don't go there. Rather put emphasis on
eliminating the mold, removing of surface dirt and discoloured or
disintegrated varnish layers or over-paint, give the painting a thin
layer of traditional varnish and start whatever you usually do then.

Mold is no fun. Get it out of there and more than half the job is
done already. And, keep it in a sunnier environment

Thomas Rebok
Fine Art Restorer
Cape Town


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                  Conservation DistList Instance 20:30
                 Distributed: Friday, December 1, 2006
                       Message Id: cdl-20-30-007
                                  ***