Reversibility of fusible polyamide

Following a query to the PSG List regarding the reversibility of
fusible polyamide (Lascaux Textile Welding Powder) not much info has
been posted regarding people's experience reversing welded
polyamide. I am turning to the Cons DistList to see if it will yield
better results and more information.

Part of the reason for the lack of response may be because *fusible
polyamide is not reversible*! Nylon is a successful resin in the
textile industry because of its mechanical durability and chemical
resistance. According to industry standards, Nylon 12 presents fair
resistance to alcohols, good-fair to ketones, good to aromatic
hydrocarbons

    <URL:http://www.goodfellow.com/
        csp/active/STATIC/A/Polyamide_-_Nylon_12.html>

    **** Moderator's comments: The above URL has been wrapped for
    email. There should be no newline.

The only response I have had of personal experience with Lascaux
polyamide from a conservator reports solubility tests consistent
with these generalizations: slow, slight solubility in alcohols;
insoluble in hydrocarbons and acetone. This does not bode well for
solvent reversal, especially when the material is infused into the
original structure.

The gross resin does not appear to bond well to natural fibers in
some initial tests I am doing in the studio. When cool, after
fusion, the gross resin does not bond well to the surface of
unprepared cotton duck. Even at fairly high temperatures, when
molten, it does not penetrate the original substrate like wax. That
is because it requires such high temperatures to melt, raising the
original structure to temperatures high enough to permit
impregnation could pose serious risks to the artifact being treated.
That may be why the powder form has been selected for use in
conservation: to effect penetration. I am guessing at this point
that like wax, it is not such a good adhesive, but bonds by
encapsulation and fusion. Will let you know when I get more results.

Should we be using this material for conservation? Especially under
circumstances where it is intimately introduced into the structure
of original materials?

Having said that, I am also looking into other, more convenient
forms of fusible polyamide: two commercially available threads and a
fusible web, 5mm wide. Will let you know more when we have had some
time to test and get additional info from the makers re materials
and manufacture.

Please post additional information and experiences regarding
removal/reversibility of fusible polyamide. Any textile conservators
have experience with this material?

Steven Prins
Santa Fe, NM


                                  ***
                  Conservation DistList Instance 21:3
                  Distributed: Thursday, May 10, 2007
                        Message Id: cdl-21-3-020
                                  ***