Halogen lamps and filtering

My question relates to halogen lamps, specifically the PAR 36 sealed
beam type.  My understanding is that halogen versions (Sylvania,
Phillips) of this lamp emit a higher level of ultraviolet light than
non-halogen incandescent version (GE).  We  don't use the halogen
type without filtering for that reason.  The problem I have is
two-fold:

    1.  The only non-halogen par 36 is made by GE, and all the types
        of these have proven to be defective, i.e. premature failure
        engendering greatly increased light changing activities in
        the museum and all that entails.

    2.  The only decent filter I have found is the Optivex filter
        developed by the National Gallery London and Bausch & Lomb.
        I informally tested these and found they do reduce the uv to
        what seem to be negligible levels. These filters are now
        very expensive ($35.00 apiece if 400 are purchased is the
        best price I have found).

Does anyone have any specific information about the uv emittance of
the PAR 36 halogen vs non halogen bulbs that they can share?  The
literature I have seen has been vague as to what kind of halogen
bulbs they were testing.

We are also interested in any information about viable alternatives
to the Optivex filters (or what you pay for them) as well as
information about what your institutions policies are in regard to
halogen bulbs in general.

James H. Whitelaw
Preparator and Facilities Technician
The Phillips Collection - America's First Modern Art Museum
1600 21st St. NW
Washington DC 20009
202-387-2152 ext. 250

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                  Conservation DistList Instance 10:65
                 Distributed: Friday, January 17, 1997
                       Message Id: cdl-10-65-001
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