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Re: silk velvet



thanks to all for the clarifying details on my rather hasty statement about silk velvet.
 
Judith  Andrewartha
Textile Conservator
National Museum of Australia
GPO Box 1901
Canberra, ACT 2601
Australia
 
phone   + 61 (0) 2  6208 5153
fax  + 61 (0) 2 6208 5167
email   j.andrewartha@xxxxxxxxxx


>>> karin.vonlerber@xxxxxxxxxx 30/06/2005 4:41:42 pm >>>
I am astonished silk would offgas sulfur. Where would the sulfur come from? From dyeing or from sizeing? Or could it be, you might have mixed that up with wool, where the polymers are interlinked with sulfur bonds? The only amino acids containing sulfur are cystine, cysteine and methionine, if I am not mistaken. Of these, only thwo amino acids are present in low concentrations in the amorphous regions of silk at an amount of 0.2% (cystine) and 0.1%(methionine) (c.f. A. Timar: Chemical principles of Textile Conservation, London 1998, p.43). Even with wool, you would have to strongly illuminate so as to liberate hydrogen sulfide from the molecular structure of wool (cf. Jean Tetrault "Airborne Pollutants in Museums, Galleries and Archives...." CCI, Ottwa 2003, p.11).
I would be very interested to know, if these small amounts of sulfur containing groups in silk have proved to cause degradation by liberating sulfur containing volatiles in any reasearch/test situations I might not be aware of.
As far as MDF is concerned, I am not sure about precise levels of various compounds in the US, but in general your regulations are more strict than ours; therefore I dare making the following statement: long times ago, MDF offgased considerable amounts of formaldehyde and acetic acid. Nowadays - at least in Europe - this offgasing is below detection limit, if the boards are left in a well ventilated room for 2-4 weeks prior to use. Depending on risk evaluation (humidity will warp acidfree board, water damage can be deleterious with acidfree board, MDF might pose some risk if not properly sealed or if the wrong type is used, PE-type boards pose considerable problems in the context of fire....) MDF might be more or less appropriate than other materials. So, as always, it depends on each single case.

Karin von Lerber
--
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 


Jane Hammond schrieb:
Thank you for the suggestions. I'm sure the objects conservator is not planning to use a product that would be so detrimental - perhaps I misunderstood, and I'll suggest an alternative. As for silk off-gassing, I should have thought of that myself rather than being so focused on being "historically accurate". Your reminder is well-taken and appreciated.

Jane

From this perspective, it should be a bit easier to find something suitable.

Than
On Jun 29, 2005, at 7:35 PM, Judith Andrewartha wrote:

hello Jane
By MDF I'm assuming you are talking about Medium Density Fiberboard?
Are you aware that MDF off gasses both formaldehyde and acetic acid, both used as part of its production?
In the sealed environment you have described this would be quite detrimental to the objects.
Also silk velvet off gasses sulphur products; I would be using a synthetic velvet as it is inert and more stable over time.
regards
Judith Andrewartha
Textile Conservator
National Museum of Australia
GPO Box 1901
Canberra, ACT 2601
Australia
phone + 61 (0) 2 6208 5153
fax + 61 (0) 2 6208 5167
email j.andrewartha@xxxxxxxxxx
>>> janehammond@xxxxxxx 30/06/2005 8:58:15 am >>>
I am looking for a source of silk velvet (light-weight), suitable for
use as a backing in an enclosed frame containing ivory/gilded metal.
The velvet will be use to cover the backboard of a shadowbox frame
which houses three ovals of carved ivory set in gilded frames.
Because of extensive mold growth the original wood backboard will be
replaced, mostly likely by MDF covered with ragboard, over which
new velvet will be placed. The original velvet can not be salvaged.

Can anyone recommend fabric sources that will sell small quanties ( a
yard?) of silk velvet suitable for conservation use? The original is
of a caramel color, so I am prepared to dye, if a white or ecru
velvet can be found.

Thank you for your recommendations.

Jane Hammond
Adjunct Textile Conservator
The Intermuseum Conservation Association
Cleveland, Ohio

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