Corrosion

Rhea DeStefano <rdestefano [at] folger__edu> writes

>... These collages are
>composed of coated metal foils (tinsels) and fabric adhered to a
>printed portrait of an actor or actress and then attached to a
>medium weight card stock.
>...
>In some cases these metal foils have corroded extensively along the
>edges or allover. To prevent further corrosion and seal the tinsels
>would the acrylic polymer B72 in a low solvent solution be the only
>option? Does anybody have any other recommendations with what to
>seal these foils to slow down the corrosion process?

Storage in a closely controlled microclimate might help. This could
be as complete as a storage environment that is free of oxygen,
moisture and corrosive gases.

Surrounding the objects with a layer of material that would trap
corrosive gases would prevent external sources of gases from
reaching the objects, but would not be effective in stopping off
gassing from the paper and boards.

I would hesitate about sealing the objects without considering
possible off gassing from the documents. In particular, I doubt that
the B72 would be of much use as an effective barrier for external
sources of the factors above, and might even delay the diffusion of
any corrosive off gassing from paper or glues beneath the metals.

I might suggest using transparent barrier film envelopes (eg Escal)
and moisture-neutral oxygen and corrosive gas scavenger packets (eg
RP-K type).

More information about oxygen-free storage and these products is at
<URL:http://www.keepsafe.ca>

js


                                  ***
                  Conservation DistList Instance 19:25
                Distributed: Thursday, November 10, 2005
                       Message Id: cdl-19-25-008
                                  ***