Passepartout tape

Does anyone know of a supplier for the black passepartout tape that
was generally used for binding glass lantern slides and other
photographic formats? I know it was still being sold within the last
few decades, but it seems to have disappeared. In default of this
material, what would others recommend as a binder for lantern
slides? I need to replace several cracked cover-glasses, and am
planning to try edging the slides with silversafe paper and either
methyl cellulose or hydroxypropyl cellulose. Any advice welcome.

                                  ***
                  Conservation DistList Instance 12:59
                Distributed: Wednesday, January 20, 1999
                       Message Id: cdl-12-59-009
                                  ***