Joe
I would suggest that your two main problems are the use of 14B gum arabic.
Try 17B. I have found that 14B often leads to stainng.
17B on Bockingford paper should get rid of the staining.
I am not clear what you mean by powder pigment but you will almost
certainly find improved results using tube water-colours..
As Tom says the gelatine you are using sounds too soft. Dick Sullivan has
the 260 bloom.
Earlier this year I compared tanned gelatine with hardened gelatine, an
acrylic size and no size on Bockingford but with brush or water jet
development. There was no staining with any of them. But the acylic size
will probably give you your goal.
Gloy gives more consistent results but, I am told, will not work with
automatic development.
Incidentally why do you develop automatically ?
Terry
Terry