Biocides for leather

Susanne Grieve <sgrieve [at] marinersmuseum__org> writes

>I'd like to know what everyone uses as a biocide when working with
>submerged or waterlogged archaeological leather and wood. The
>following biocides are what I have come across in my research:
> ...
>    Adesol and Panacide ...
> ...
>    Kathon CG ...
> ...
>    Dowicide 1 ...
> ...
>Can anyone who has worked with these recommend one over the other?

Panacide is a chlorophenol and Dowicide 1 a sodium-orthophenylphenol
belong both to the same chemical family--the phenols. Kathon CG is a
isothiazolon and I don't know the chemical composition of Adesol.

Each use of fungicides requires exact knowledge of the impact on the
material. Thus I recommend in my seminars gaseous rather than direct
applications. Isothiazolone does not work gaseously, for example, as
a fungicide. My own investigations proved that. Phenols are again
frequently very poisonous for the conservator and should be
exchanged for less poisonous phenols--for example chlormetakresol.
Investigations at paper and textile fibres showed after a directly
application a pronounced damage, which does not seem justifiable
from conservation points of view.

Although I'm not a leather conservator, I do know about the problem
of preserving wet leather. In my daily practice, due to my auxiliary
microbiological qualification, I advise colleagues in handling
contaminated objects. For example we did without bringing in
fungicides in the context of the consolidation process. The leather
object was correctly dried under conservation aspects under aeration
with chlormetakresol. Thus it did not come to a growth of mold. I
think, that Panacide and Dowicide are also been suitable for an
aeration. It must be microbiologically controlled.

Another way is the direct use of isothiazolons, which can be also
very poisonous. In addition, the correct concentration here is
crucial. A possible concentration from 1% to more than 20% depending
strongly on the material dampness. Beyond that it can result in
white deposits on and in the material, and the effect on leather has
not been sufficiently investigated. I would be very much interested
in publications if anyone know them.

On cellulose fibers a treatment with Isothiazolons does not have
negative effects--in particular the azols (Clotrimazol, Thiabendazol
etc.). They are classified as innocuous for humans, in particular
Clotrimazol. In contrast to the gaseous treatment, the direct
application with Azols provide a certain preventive protection from
future infestation, which cannot temporally be defined clearly.

We examined the fungicidal effectiveness of all fungicides with a
surface defined microbiological sampling, in which the growth rates
are evaluated by the conservator and compared with the condition
before the treatment.

I hope, I have helped you and wish you much success with the choice
and the correct application of a suitable material.

Christina Meier
MicroConservation


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                  Conservation DistList Instance 20:13
                 Distributed: Friday, September 8, 2006
                       Message Id: cdl-20-13-004
                                  ***