Flameproofing velvet curtain

Katharine Untch <kuntch [at] getty__edu> writes

Karin von Lerber <karin.vonlerber [at] prevart__ch> writes

>    *   has somebody had experience treating historical cotton
>        (velvet) with fire proofing chemicals (and with cleaning
>        cotton velvet before doing so)?

Although it is obviously expensive, I would suggest a replica curtain:

    *   I am not optimistic that you could find a fire retardant to
        apply that would not deteriorate the historic fabric (see
        case study abstract below). An inherently flame resistant
        fabric might be preferable.

    *   Application of a liquid to an old velvet is very likely to
        affect the even appearance of the nap.

    *   Would the organization's insurance company cover injuries if
        the curtain tore and fell on someone?

    *   A new curtain could be provided through a fund-raising
        campaign, preferably to special benefactors (it's quicker).

This may give you some ideas:

I was asked to consult on the yellowing of a cotton fabric used to
line the walls and ceiling of a reception room in an official
residence. (This was a striped fabric, originally yellow, white, and
pale blue, in which all the colours had shifted to yellow/ochre/rust
tones. The curator wished to replace the fabric but sensibly wanted
to determine the cause of yellowing first.)

After an initial examination and discussions with caretakers ruled
out contaminants from an old oil heating system, food preparation
and service, pest control sprays, candles, previous cleaning
attempts, water infiltration, and acidic adhesive and/or backing
materials, a number of observational factors (including darkening of
the reverse as well as obverse, and comparison to non-installed
samples) suggested the possibility of a fire retardant as the cause
of yellowing.

Analyses through the kind auspices and expertise of Parks Canada and
CCI of the backing and adhesive materials, as well as of the
installed and stored fabrics, led to the conclusion that the main
culprit was ammonium sulfate, an applied (acidic) fire retardant.

Dr. Nancy Kerr, of the Dept. of Human Ecology at the University of
Alberta provided valuable advice:

   "The article by Bonnie Halvorson (Flame Retardant Finishes for
    Textiles ) in the TCN (Fall 95, No. 29) is very good. ..."

   "The best solution for the wall covering is to buy a fabric that
    is inherently flame resistant (FR). Modacrylic is good and some
    polyesters are as well. Suppliers of fabrics for the Interiors
    trade like Maharam sell fabrics which have an FR rating. The
    fabric specs will say what flammability tests have been passed
    like "complies with NFPA-701". Maharam sells Trevira polyester
    fabrics that meet various fire codes and the brochures show a
    wide variety of fabrics. Their headquarters: Box 6900, Rasons
    Court, Hauppauge, NY 800-221-5619. [Note: this was in 2000, so
    sources may change.]

   "There is no way to guarantee 20 years of service to a wall
    covering unless you buy a fabric that is inherently FR. If the
    designer uses a fabric which must have a finish on it, I don't
    know which finish to recommend. Many of them have ammonium
    sulfate or phosphate and other related salts. The topical
    finishes that Bonnie Halvorson reviews in her  paper all have
    ammonium salts. Borax/boric acid is an old finish that also
    causes yellowing of fabrics and loss of strength. The ammonium
    sulfate that was extracted from the current wall covering is
    responsible for the colour change and any tendering. Light is
    part of the reaction. If acidic breakdown products are formed
    over time cellulosic fibers will become weak but acidity doesn't
    cause yellowing of cotton. The yellowing is a different
    reaction, usually a light-induced oxidation of a molecule in the
    finish and the creation of a yellow/brown chromophore."

    [reproduced by permission of Dr. Kerr.]

hope this is helpful,

Lisa Mibach


                                  ***
                  Conservation DistList Instance 17:41
                 Distributed: Monday, November 3, 2003
                       Message Id: cdl-17-41-002
                                  ***