>Under no circumstances would I use the following formula for cleaning
>an original which I wished to preserve - especially Daguerreotypes. A
>paper presented at a recent meeting of the Photographic Materials
>Group (PMG) of the American Institute for Conservation of Historic &
>Artistic Works (AIC) suggested that Daguerreotypes treated using
>Thiourea have begun to deteriorate as a result of that treatment. I
>believe the current thinking, at least with regards to Daguerreotypes,
>is that unless the image is at risk of loss and requires stabalization
>nothing should be done (this includes removing cased originals from
>their cases). I'm sorry I don't have the specific reference for the
>paper I mention handy - if anyone is interested email me and I will
>send it to you when I find it.
For those interested, the paper by Edmundson & Barger referred to by Greg
is in AIC's _Topics in Photographic Preservation_, Vol. 5, 1993, pp. 14-20.
Roderick Hook
PhotoArchivist & Conservator
(Member AIC)
Roderick Hook
PhotoArchivist & Conservator