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Subject: Colorimeters and densitometers

Colorimeters and densitometers

From: Karen Potje <kpotje>
Date: Wednesday, June 13, 2001
I would like to know if many institutions have turned from
densitometry to colorimetry to monitor the effects of exhibition on
photographs. Among the many advantages of colorimetry we like the
fact that measurements taken with one colorimeter can be compared
with measurements made by another instrument at another institution.
This would make it easier and less costly to monitor for changes
throughout the course of a number of loan venues.

We presently work with a densitometer which is not portable.  Since
comparisons of readings taken by different densitometers cannot be
trusted, we have, on occasion, required that a photograph which we
suspected to be light sensitive be unframed and monitored on arrival
at the borrowing institution with the borrowing institution's
densitometer.  Then, at the end of the venue, it had to be unframed
and monitored there again in order to ascertain that there was no
change in the photograph and it could be exhibited at the next venue
on the tour.  We have also had photographs shipped back here for
densitometric monitoring between venues when no densitometer was
available at the borrowing institution.  This has proven to be very

It would be easier to justify the purchase of a colorimeter if,
instead of always having to send a conservator to the borrowing
institution to take after-exhibition colorimetric measurements, we
knew that we could occasionally save some money by relying on
borrowing institution to carry out their own after-exhibition
colorimetric measurements which we could compare with our own
before-exhibition measurements taken here.  Are many institutions
adopting colorimetric monitoring?

Karen Potje
Canadian Centre for Architecture

                  Conservation DistList Instance 15:3
                  Distributed: Thursday, June 14, 2001
                        Message Id: cdl-15-3-019
Received on Wednesday, 13 June, 2001

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