U of S | Mailing List Archive | alt-photo-process-l | two questions about gum

two questions about gum

I have noticed that my Daniel Smith Perylene Red stains the margins fairly heavily EXCEPT when it is the first layer. Is this kind of behavior common? Am I missing something? It took me quite a few prints to determine this since I have been printing that layer 2nd or 3rd and bemoaning the stain. Then I realized my 10x10 test chart showed no stain and made a print with the Magenta layer first--no stain. I am printing on unsized Fab Aristico.
On a related topic: After determining the exposure time and curve for each of the three colors I made a test print which was WAY too dark. Cutting the exposure time by nearly 2 stops helped. Katharine Thayer confirmed off-list that it is customary to have to cut back, though if I remember right she suggested using less pigment rather than cutting exposure. Is there any rule of thumb for cutting either the pigment or the time?
Thanks. Charles Portland, Oregon