I'd like to make an addition and correct an interpretation of my remarks
on scanner light intensity.  The lamps in the scanners I measured were
the *cold cathode type.*  They put out light not electrons with
wavelengths or energies beyond visible (visible light including both
infra red and ultra violet for this discussion).  The lamps heat up
during use; they are not cold; cold cathode is a lamp type.

I did not measure UV output for two reasons: (1) the duration of maximum
output runs about 5-15 seconds, (2) it was too difficult and expensive
to for me get a UV sensor to make the measurement, for such a small
amount of potential UV output.  I'm sure the UV output of the cold
cathode lamps is not greater than that of the sun.  Therefore the UV
exposure would have to be the equivalent of 1300-2500 lux (about 6% of
the average sunlight exposure, 40,000 lux, through most of the US) in a
fraction of a minute (5-15 seconds) of sunlight.  To me, this is a very
small amount of UV energy.

Timothy Vitale
Preservation Associates
831-684-2731