Hi Chris,
The combining of startch and the salts is just a variation on a theme. I
normally do not use starch for sizing, but I would assume that you could
use this combination method because a starch solution will last much longer
than a gelatin. Two or three heatings of a gelatine based sizing or salting
solution and the gel will no longer set. I also have found that after
about a week, the gelatin starts to break down and becomes very smelly.
The starch solution will keep for a almost a month if kept in a sealed
container and refridgerated. I use gelatin sizing because I prefer the color.
Just as a side note, I tried using aerosol laundry starch last week with my
standard negative to see how it would work. When the salting solution and
later the sensitizer were applied, the starch loosened up. I mixed them
together for the heck of it. After the mess was dry, I exposed for the
print as normal for me. To my surprise, the print (although streaky from
too much goofing with the chemicals) turned out to be a stop and half
faster and a good deal contrastier than I usually see. I haven't followed
up on this...yet.
I am sorry that I can not help with your bromoil and POP questions, I
haven't had much experience with these processes.
Good Luck
Joe P.
Tucson, AZ