jewelia (jewelia@erols.com)
Tue, 30 Mar 1999 13:08:26 -0800
generally--as far as i know--dyes are not used as opitical brightners in
paper--one reason being is that it is tough to dye something lighter than
what it already is--two methods are used to whiten pulp--bleaching of some
sort and optical brightners--almost all nice bright "white" papers are made
from bleached fibers and this process can cause some archival and
environmental concerns...optical brightener is a term used for additives
sometimes used to whiten a bleached pulp (usually) more and, perhaps moreso,
to increase the opacity of the paper...the usual optical brightner is
titanium dioxide -- a pigment, not a dye. titanium dioxide is quite stable
and is a common pigment used for white "color" paints and other mediums.
paper mills regard their recipes as trade secrets and tend to use ambiguous
terms like this...other pigments could be used i suppose but i expect
titanium dioxide is the highly prevalent choice...
the practice of using titanium dioxide began in the mid-thirties and i have
never heard of it causing any archival problems--although it could be in
papers that have archival problems for other reasons. but titanium dioxide
use in paper can have drawbacks for some---many forgers have goofed and been
caught by the presence of titanium dioxide in that "old" found piece.
regards
jewelia Margueritta Cameroon
paper femache'
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