Quote Originally Posted by Ian Grant View Post
Alessandro, there are 3 silver solvents which are typically used in B&W reversal first developers, Thiosulphate, Thiocyanate and now DTOD which is C6H14O2S2 3,6-Dithiaoctane-1,8-diol. Of these Thiosulphate is the least common and it's not used in any modern commercial developers (1940's onwards), and only Ilford recommend using it, in their reversal processing data sheet.. At one time Ilford recommended using the first developer from the Dufaycolor process for B&W reversal, that uses Thiocyanate.

I've not used Dokumol but it's quite similar to Ilford PQ Universal or May & Baker (Champion) Suprol. Suprol was widely used for commercial B&W reversal processing and there was a very detailed data-sheet available in the 70's, you had to add 4 gm's per litre of Sodium or Potassium Thiocyanate to a 1+4 working solution.

So if you can standardise on a good readily available normal PQ print developer use it at twice the normal working strength, ie 1+4 instead of 1+9, and try it with Thiosulphate & then Thiocyanate but you'll almost certainly get better results with the Thiocyanate.

The Orwo/Filmotec 829 first developer is a similar PQ developer but has approx double the Hydroquinone and increased Bromide which will give give better contrast & Dmax. Potentially it looks to be an excellent First developer.

Somewhere I have a short trouble shooting guide for reversal processing, I'll post here on APUG in the next few days.

Ian
I've got excellent results, at least to my eyes, using Tetenal Eukobrom and Dokumol with 2,5g of thiosulphate in 250ml of working solution.

Dunno why thiocyanate will yield better results than thiosulphate.