Dear Kari R. Kohlhoff,

Your inquiry was forwarded to my attention by our information officer, Ann N'Gadi. Silk is very susceptible to the static charge found with many brands of Plexiglas. The record is having a silk embroidered hanging ripped apart in a mere 2 1/2 years because the free-standing hanging was a guard-custodian's favorite and he cleaned and wiped the surface of the Plexiglas daily, and because the hanging was 2 inches away. That's how strong the pull is. Pretty amazing.

 

Either the Plexiglas needs to be far removed from the silk (6 inches or more) or directly atop it (as a pressure mount). Textile conservators often prefer Plexiglas to glass because the Plexiglas is 1/3 the weight of glass, because Plexiglas does not shatter, and Plexiglas stays at room temperature.

 

Glass is cold to the touch and can help create a microclimate that causes 18th and 19th century embroideries of silk or wool to outgas fractions of soap residues that were absorbed long ago. These residues can create a fog or milky haze on the glass that is mistaken for mold. Several studies were done on this topic by the Museum Conservation Institute: "A Study of Deposits on Glass in Direct Contract with Mounted Textiles"  by Susan C. Heald, Lucy Commoner and Mary Ballard The Textile Specialty Group of the American Institute for Conservation Postprints vol 3 1994 pages 7-18 and "The Spontaneous Transfer to Glass of An Image of Joan of Arc by Tim Padfield and David Erhardt ICOM committee for conservation: 8th triennial meeting, Sydney, Australia, 6-11 September, 1987. Preprints Grimstad, Kirsten (Editor);  Marina del Rey: Getty Conservation Institute, 1987 Pp.909-913.

 

Sincerely,

 

Mary W. Ballard

Senior Textiles Conservator,

Museum Conservation Institute, Smithsonian Institution

4210 Silver Hill Road, Suitland MD 20746 U.S.A.

tel: 301-238-1210 fax: 301-238-3709

email [log in to unmask]

 

 

-----Original Message-----

From: Museum discussion list [mailto:[log in to unmask]] On Behalf Of K. Kohlhoff

Sent: Wednesday, April 02, 2014 1:40 PM

To: [log in to unmask]

Subject: [MUSEUM-L] Silk under glass vs. Plexiglas

 

Hello Listers,

 

We have a silk wall hanging that has been framed under glass for decades and exhibited in a historic house setting.  Later this year it will be removed from its location in the house and placed on exhibit in one of our museum galleries.  Prior to its relocation it will be reframed as the style and appearance of the current frame have been deemed inappropriate.  I am trying to determine if it is safe to replace the glass with Plexiglas during the reframing process.  So far I have not found much helpful information out there on whether silk is affected by static electricity.  The wall hanging is around 110 years old but appears to be in good condition.  There does not seem to be any matting between the glass and the silk, and it is impossible to tell just by looking if the silk is by this point stuck to the glass.  Would anyone have any recommendations about this or know of any resources I might consult?

 

Regards,

 

Kari R. Kohlhoff

Curator of Collections

Siouxland Heritage Museums

 

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