Silica gel

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. It must be
disposed of as hazardous waste, EEC list II substance and cannot
contaminate soil or water. Gloves lab coat and effective dust mask
(FFP2 or 3) should be worn. (I did anyway because I was worried by
the silica.)

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. It would also
be much cheaper. Of course, it does mean that if the silica gel is
ever disposed off, the amount of waste is more. Your comments
colleagues please,

Paul Harrison
Metals Conservator
Hong Kong Govt


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                  Conservation DistList Instance 14:16
                 Distributed: Sunday, September 3, 2000
                       Message Id: cdl-14-16-021
                                  ***