There's not a lot of difference in practice , they both contain Ammonium Thiosulphate and Sodium Selenite. KRST contains Sodium sulphite and while it's not listed in the Ilford MSDS sheet it may be present.
Fotospeed Selenium toner is very similar to KRST but then they have ex-Kodak employees.
The formula was looking for is slightly different, I've just found it in a War-time Kodak Formulary, from Kodak Research, Harrow
Kodak T55 Selenium Toner *
| Sodium Sulphite (anhyd) |
150g |
| Selenium (powder) |
6g |
| Ammonium Chloride |
190g |
| Water to
|
1 litre |
Dissolve the sulphite in about 700 ml of hot water, then add the selenium powder and boil until it is completely dissolved. Allow the solution to cool; then add the ammonium chloride and stir until it is dissolved. Finally make up to the required bulk with cold water.
For use dilute 1 pare of stock solution with 5 parts of water.
Prints should be fixed and well washed before toning in the above solution for 10 to 15 minutes at 18° C. (65° F.). Finally wash well before drying.
CHARACTERISTICS AND PURPOSE
A single-solution toner for chloro-bromide papers and warm-tone lantern slides yielding a variety of tones from brown to red-brown cording to depth and colour of the developed image. Images toned in this bath may be further enriched by subsequent toning in T.52.
* Available as "Kodak" Selenium Toner In concentrated solution form.
Ian