I found this recipe on the net.
distilled water -- 75 ml
potassium dichromate -- 9 gr
hydrochloric acid -- 6.5 ml (more to reduce intensity)
add cold water to make 100 ml
I tried it and it works quite well. My question would be how long would this stuff last on the shelf?
This formula is intended for one-time use. As such it has little reserve capacity and should not be saved. For safety reasons not something that should be kept on the shelf.
What I stated is the stock formula. It is then mixed 1:10 for use, and that is one time use.
Outside of it containing dichromate and hcl, does it create an additional combined hazard?
What would be the advantages of this formula over the more standard selenium-toner, for negatives? (I'm assuming that you were using it on film, rather than paper).
It's very much stronger in it's intensification.
Originally Posted by MartinP
+1 and you can repeat it. I also had everything to make it.
In two parts the Chromium Intensifiers last decades. Ideally you need a Bichromate solution Part A and a weak HCl solution as Part B.
I guess the magic approach is to split them up and do 1:1:20. Thats workable. It's just not something you would use every day, hence my question.
That formula is for a ready to use, one-shot intensifier. It works well. You bleach the negative in the solution and then redevelop in something like Dektol.
Kodak IN-4 chromium intensifier
Water 1 l
Potassium dichromate 90 g
Hydrochloric acid (conc) 64 ml
Dilute 1:10 for use. Bleach negative thoroughly in the above solution. Wash 5 minutes, then redevelop in room light in a non-staining developer without excess sulfite. Degree of intensification may be controlled by degree of redevelopment. After redevelopment, rinse negative, fix, and wash. Repeat process for greater effect.