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Subject: Didecyldimethyl ammonium chloride

Didecyldimethyl ammonium chloride

From: Karin von Lerber <karin.vonlerber>
Date: Monday, June 11, 2007
Together with a team of 5 textile conservators we will have to treat
all church textiles from an important baroque church in Switzerland,
amongst others 45 antependia. Due to bad air circulation, the annex
in which the textiles have been kept fostered a quite serious mold
outbreak in some cupboards and on some of the objects. The building
shell and cupboards will be changed (this is not part of my
question). We have been asked to do an interventive conservation
treatment on all 45 antependia, all of them still mounted on their
wooden strainers, all of them very dirty.

The mold expert contracted by the monument preservation department
has been working in the field of heritage preservation for a very
long time. When discussing possible treatment options with regard to
their effect of promoting a future mold outbreak, we were told to
use a quaternary ammonium salt (didecyl dimethyl ammonium chloride)
in a last rinsing bath. This specific quaternary ammonium salt--we
were told--was the most pure form of the group and therefore used in
heritage preservation. As this biocide is similar to a detergent,
will bond like a substantive dye to the surface of a textile,
and--just by my non-specialist guessing from the chemical
description on the data sheet--seems to be very reactive, I am a bit
hesitant. Even more so when--in spite of the suggested widespread
use--we could find hardly any published research on the long term
effect of quaternary ammonium salts on wool, silk, linen etc.

In CAMEO we did find a descriptive entry, but nothing in regard to
the effect on objects. The only article I found (on AATA) is

    Johnson, D.G. and Reagan, B.M.
    Influence of antimicrobial agents on dye fading and fiber
    yellowing in nylon. Textile chemist and colorist 22, no. 4 (1990
    Apr), pp. 2124 [English]".

In the abstract they state that: "The quaternary ammonium
salt/organo-tin and phenol mixture caused the greatest color change
in the dyed and undyed nylon." This does not make me less hesitant,
to be honest.

Does anybody have unpublished research on the effect of quaternary
ammonium salt or could direct us to further published research? What
other options could you suggest?

The original intent of the conservator in charge of this project
was: thoroughly surface clean with aspirator (HEPA-filtered) take
off the wooden strainer, wetclean. remount. (This original proposal
is under review and will most probably be modified; this is not the
aspect of the treatment I would like to discuss here.)

During this suggested treatment, the number of spores is expected to
be reduced exponentially, as much by vacuuming as by wet cleaning
with a detergent. However, I am worried that during wet cleaning and
while drying, remaining, dormant spores might be activated (it can
take days until the fibre has really reached moisture equilibrium
content again, even though the textile seems "dry", and traces of
remaining detergent may act as activator as well).

I therefore suggested drying the object between two layers of
blotting paper, the lower one being sprayed with 70% Ethanol, which
would seep through the textile. 70% Ethanol is not *really* a
biocide, as it is not 100% effective, however the amount of living
spores can again be reduced quite drastically. (this I conclude from
Mary-Lou Florian: Fungal Facts, London 2002.) This suggestion of
Ethanol then lead to the mold specialist's proposal of quaternary
ammonium salt treatment, as in his view, Ethanol is not a biocide.

Any ideas, reflections, and especially experience you could share
are most welcome. Is there maybe an alternative to quaternary
ammonium salt providing the same biocidal effect?

Karin von Lerber
Prevart GmbH
Oberseenerstr. 93
CH-8405 Winterthur
+41 52 233 12 54
Fax:  +41 52 233 12 57


                                  ***
                  Conservation DistList Instance 21:11
                   Distributed: Sunday, June 17, 2007
                       Message Id: cdl-21-11-013
                                  ***
Received on Monday, 11 June, 2007

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