Glass window sign

Krista Cooke <museum [at] cancom__net> writes

>We recently received a glass window sign (ca. 1940s) printed with
>black and gold leaf type print.  Much of the gold leaf and some of
>the black are peeling and there are severe losses overall.  Every
>time the sign is moved or has air stirred above it, the peeling
>worsens and small flakes are lost.  It will be a year or more until
>the sign can be seen by a conservator.  As a curator, what small
>steps towards preventative conservation can I take to protect the
>piece. I am concerned about putting any kind of backing onto the
>glass for fear of crushing or creating friction against the curled
>edges of the text.

The major preventive concerns would be: orientation of the flaking
print, proper support, and control of vibration/movement, static
electricity, air flow and temperature/humidity.

Store the glass sign horizontal with the print upward to limit
losses. Do not place anything in contact with the curling, lifting
print surfaces. Although the size of the piece is pertinent (the
larger the span of glass the greater the potential for
deflection/movement), in any case, a solid, flat support is
necessary. A shelf or table can transmit vibration from the floor so
it would be helpful to isolate the support and keep it away from
foot traffic, heavy material movement or construction activity. I
would lay the sign on a soft, dense polyethylene foam or stable felt
material (avoid polyurethane foam--it is unstable) for cushioning
and to absorb vibration. This could be done with a number of foam
strips rather than one large piece of foam. The weight should be
distributed evenly over the entire frame (I'm presuming the sign is
in a frame of some kind) but if the sign is large the glass may sag
in the center so additional support may have to be provided
underneath. Soft unbuffered acid-free tissue, blotting or barrier
paper or waxed paper could be used between the sign and cushion
material if there is concern about possible reaction of  the sign's
surfaces to whatever cushioning material  is used (weight may be
significant if the sign is large).

If the sign is too large to fit into a box (the easy solution) you
could create a sturdy 3-6 inch high 'wall' around the sign from
'foam-core' or acid-free corrugated type paper board. Avoid shiny or
smooth surface plastic type materials since they can hold static
charges on their surfaces. Cover the cardboard perimeter 'wall' and
sign beneath, with a stiff, neutral pH cardboard or 'foam-core'
'lid'. Alternatively, a medium to heavy weight cotton, or other
plant-based fabric can be utilized as a cover. Synthetic fabrics can
hold electrostatic charges that may pull the separating print
material from the glass. Place weights outside the sign to hold the
fabric cover flat above the print surface. There are other possible
methods to protect the glass sign that may work better for you but
the main things are limiting air turbulence, static electricity,
dust and contact with the detaching print surfaces.

If possible, keep the glass sign in an area with a relatively
consistent temperature (on the cool side, preferably) and relative
humidity. A consistent median relative humidity (say, 45-55% RH)
will limit expansion and contraction of vulnerable materials and
limit static electrical charges promoted in a dry environment. Of
course, keep the sign away from air vents or other sources of direct
air flow. These preventive measures should keep the sign stable
until conservation treatment.

Richard Fuller
Conservator,
Doon Heritage Crossroads


                                  ***
                  Conservation DistList Instance 15:27
               Distributed: Thursday, September 27, 2001
                       Message Id: cdl-15-27-006
                                  ***