'Speaking of personal choices, my printing procedure is as follows. I coat Arches Platine paper with a Pd/Pt sensitizer (3:2). I use more FeOx than metal: a 4x5 print, for example, is coated with 6 drops FeOx Sol.1, 3 drops of Pd, and 2 drops of Pt. I control contrast not with the sensitizer, but the developer, specifically Potassium Oxalate developer with Sodium Dichromate as the sole contrast agent. I use Kodak Hypo Clear for three clearing baths of 5 minutes apiece. Processing is done in a Jobo drum at 25rpm. After 25 minutes in an archival washer I dry the prints face up on fiberglass screens and then soak each for one minute in an 6% solution of Liquitex Acrylic Gel Medium which increases the Dmax and tonal separation, cools the print color slightly, and also gives the print a slight amount of glossiness.'
I have never heard of this being used in the platinum printing process let alone used to modify dmax, tonal separation, print color or the glossiness of the final print. I think the article was written some time ago. I should recieve some in the next day or so and will be testing it out.
Further info on Liquitex Acrylic Gel Medium
Liquitex Gel Mediums add body to thinner paint for impasto techniques as well as extending colour volume and adding transparency. Gels also add “open time” as they dry slower than thinner films. These mediums also modify acrylics in a variety of ways and tend to improve adhesion and durability.