I believe United Supply (Ft. Wayne, Indiana) also carries it.....Didn't see
it in my old SAX catalog and am too lazy right now to get my new one
upstairs.
And for monoprinters....The Gum Arabic listed with the Litho-Sketch supplies
does not work very well for the processes mentioned by Woody (it is too
thinned down). You will want to get a higher quality from a print supply
catalog (like Daniel Smith). Litho-Sketch uses Gum Arabic to protect the
plate after printing. It really isn't necessary as you usually only do a
small edition with students. I have found that students get the plates so
wet with the de-sensitizing solution (which you MUST use) that we only get
five prints off the plates.