Quote Originally Posted by Photo Engineer View Post
No. The emulsion is found throughout the gelatin in the light sensitive layer, and every processing solution must diffuse to the bottom of that gelatin layer to carry out the assigned function such as development, stop and fixation. In the case of the fix step, the fixer chemistry must diffuse inward and then it must diffuse outward while carrying the extra Silver Halide salts.
I think I understand - thoroughly swelled gelatine which allows the fixer to enter and exit it fast is preferable because it's necessary for the fixer to penetrate it wholly and do it fast both ways.

In the case of FB papers, the paper itself is totally wetted with the chemistry in water in each step. Baryta has an affinity for Hypo, and thus the wash step with Baryta papers becomes much more difficult and critical.

Is baryta also pH sensitive? If it's not the role of alkaline vs acid fixer diminishes. Or am I wrong?