Quaternary ammonium salt - Didecyldimethyl ammonium chloride

["Karin von Lerber, Prevart GmbH" <karin.vonlerber@xxxxxxxxxx>]

Dear Colleagues,
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 hesitating. 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 ammounium salts on wool,
silk, linnen 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Does anybody have unpublished research on the effect of quaternary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:
thorouhly surface clean with aspirator (HEPA-filtered)
take off the wooden strainer
wetclean
Remount. (This originial proposual 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 amount of spores is expected to be
reduced by exponentials as well 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 is
most welcome.
Is there maybe an alternative to quaternary ammonium salt providing the
same biocidal effect?

Sincerely,
Karin
--
Karin von Lerber
Prevart GmbH
Oberseenerstr. 93
CH-8405 Winterthur
Tel. +41 (0)52-233 12 54
Fax. +41 (0)52-233 12 57
e-mail: karin.vonlerber@xxxxxxxxxx
www.prevart.ch