Silica gel

Paul Harrison <paulehar [at] netvigator__com> writes

>I heard on the British archaeology discussion list of work conducted
>at the Institute of Archaeology, that the indicating part of
>blue/pink silica gel, the cobalt chloride should be treated with
>care, as it is a potential carcinogen by inhalation. ...
>...
>I was wondering why do we not dilute the problem? If we added a
>small percentage of 'blue' silica gel to non indicating plain white
>silica gel, it would indicate for the rest of the silica gel and our
>exposure to the cobalt chloride would be much reduced....

I have always used the non-tinted version.  Small relative humidity
indicator papers are available which can be placed on the silica gel
to indicate when it needs regenerating.  It should be possible to
order these from any conservation materials supplier.

Tessa Ramseyer
Archaeological Conservator
Hong Kong


                                  ***
                  Conservation DistList Instance 14:17
                Distributed: Tuesday, September 12, 2000
                       Message Id: cdl-14-17-006
                                  ***