One thing that came to my mind, you haven't mention sodium citrate in the formula, it is not essential but it decreases contrast and affects the color as well as the gelatin ratio. When I tried to increase contrast of the print without adding potassium bichromate, and keeping the negative density a constant.
I completely eliminated sodium citrate and increased gelatin ratio to %3 the resulting prints color were according to a painter friend of my mine was diarrhea brown even when dry. The worst I have ever seen. I like the salt print colors without gelatin very much but I use gelatin anyway. BTW I am fairly new to the process myself.

You should take a look at Young's applied science thesis on the color of Salt Prints, I find it a bit more comprehensive than the Salt Printing Manual.
http://researchbank.rmit.edu.au/eser...7850/Young.pdf

Bleach is as stated by the others is probably related to exposure, but the final color might be a combination paper, gelatin ratio and salt formula.