alum as paper size
Deborah Derby (dderby@getty.edu)
Tue, 25 Jul 1995 12:54:46 -0800
Sorry to jump in so late, but in responding to the alum issue in
general: Alum is in disfavor as a paper size because it is acidic and
therefore catalyzes the deterioration of paper. So, when David
Soemarko refers to the "yellowing" of Chinese watercolors as due to
the acidity he is correct, except that the acidity is most likely due
to the alum. I realize that there are numerous references to the use
of alum in the historic literature (Judy Seigel), but alum was a
regular additive in the papermaking process at that time and the
concept of acidic/poor quality paper (as we know it) was relatively
new. While alum can have disasterous effects on poor quality paper,
it is debatable as to the "real life" effects it can have on good
papers (like BFK and other cotton rag artist papers) regardless, I
would recommend that if the longevity and archival quality of your
work is important to you, you should avoid using alum in place of
gelatin size.
One other note on 20 x 24" negative production and the xerox machine,
you can run polyester sheet through some xerox machines, so it may be
worthwhile to investigate that as an option if you are willing to wax
or oil paper negs.
Deborah