Mold on leather

Corine Landrieu <landrieu.conservation [at] hotmail__com> writes

>I am currently looking at various possible options for the treatment
>of a leather artifact infested with mold growth.
>
>The mold appears to have been dormant for a number of years.  I am
>thinking about using an HEPA vacuum and following up with isopropyl
>alcohol applied with cotton swabs to remove as much of the mold as
>possible.

I have just supervised a thesis on this topic at the State Academy
of Art and Design in Stuttgart Germany. I hope that the results will
soon be published.

I would recommend you to use dry cleaning methods. Ethanol or
isopropanol are most efficient in killing microorganisms in a
mixture of 70-80% alcohol and 20-30% water. As the alcohol
evaporates more quickly than the water, the percentage of alcohol is
soon too low and in the end it leaves you with a wet surface, which
may enhance further mold growth or even activate the dormant fungus.
Also, the alcohol/water mixture needs several minutes to act on the
fungus, hence a fairly dry application with a cotton swap rather
acts by mechanical removal than by the action of the alcohol.
Satisfying disinfection results with ethanol were only achieved by
poultice application for several hours (the alcohol penetrated the
leather samples deeply; in a fairly dry application the disinfection
results were not satisfying) and by soaking the entire leather
sample for 10 minutes in the alcohol water solution. Both
applications were only tested on mock ups and I would not recommend
them on cultural heritage objects.

As many leather objects do not tolerate wet cleaning procedures we
tested several dry cleaning methods. All dry cleaning methods were
performed after a thorough vacuum cleaning with a soft brush. Make
sure that you clean the object in an enclosed area, as the HEPA
vacuum cleaner can never absorb all the fungal structures and you
don't want them to be spread in your work space. The best is a
microbiological laminar flow, if not available use a disposable tent
or transparent cleaning box with holes for your hands and the vacuum
cleaner nozzle. Most of the fungal structures are being removed by
the vacuum cleaner, however, further dry cleaning will remove more
of the fungal structures and hence give more safety to people and
the object itself. We tested the following dry cleaning agents:
microfiber cloth, latex sponge, Akapad, Groomstick and cotton swabs
coated with Lascaux HV 360 (an acrylic resin with a Tg of -28 deg. C
hence remaining tacky). Dry cotton swabs were indirectly tested, as
they were used for sampling the fungi for evaluation. Dry cotton
swabs proved to remove less fungal structures than the tested dry
cleaning agents. The best dry cleaning results were achieved with
the latex sponge, both on the smooth epidermal side as well as on
the fibrous flesh side. For the smooth epidermal side the best
cleaning result is already achieved after a short time, however, at
the rough, fibrous side longer cleaning significantly enhances the
result. Furthermore, make sure for the epidermal side that you move
the latex sponge with the direction of the follicle (in the
direction that the hair grew out of the skin) as this again enhances
the cleaning result.

Dr. Stefanie Scheerer
Microbiologist, PhD and Objects Conservator
Lecturer at the State Academy of Art and Designn


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                  Conservation DistList Instance 26:15
                 Distributed: Sunday, September 2, 2012
                       Message Id: cdl-26-15-003
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