From: Richard Morris (richard.morris@brunel.ac.uk)
Date: 02/04/00-02:23:23 AM Z
Glass - it depends on whether you are repairing or conserving.
Richard Morris
On Thu, 03 Feb 2000 10:54:13 -0700 (MST) Wayde Allen
<wallen@boulder.nist.gov> wrote:
> On Thu, 3 Feb 2000, Richard Morris wrote:
>
> > On cleaning the glass, if you want to use the original, beware that some
> > of this glass is very "soft" and easily fractures. I actually cleaned the
> > glass of a Lerebours dag - now many thousands of dollars worth of image!! -
> > but it had to be reused and remounted. The underside of the glass appeared
> > to have a mercury deposit but very careful rubbing with a moist cloth using
> > a bit of vim did the trick. But my heart was in my boots as I did it! It
> > had to be done as the image was completly obscured by the dirty glass.
>
> I think one really should consider replacing the cover glass rather than
> just cleaning it. The problem is that the glass ages and softens. Then
> it begins to flake, droping very small pieces of glass down onto the dag.
> plate itself. I don't believe that cleaning and replacing the existing
> glass stops this process.
>
> NIST recently redesigned and built a new box for holding the United
> States Charters of Freedom (Declaration of Independance, Bill of Rights,
> etc.) due primarily to the deterioration of the cover glass. See
> http://www.nist.gov/public_affairs/Charter/charters_of_freedom_project.htm
>
> - Wayde
> (wallen@boulder.nist.gov)
>
>
Richard Morris
Brunel University, UK
richard.morris@brunel.ac.uk
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