Quote Originally Posted by nworth View Post
Wrong! DTOD is HOCH2CH2-S-CH2CH2-S-CH2CH2OH (1,2-di(2-hydroxyethylthio)ethane). It was substituted for 9.1 ml of sodium thiocyanate (51% solution) (not thiosulfate) to turn D-94 into D-94A.

D-94 is very different from D-76. D-76 does not have the energy to make a good reversal first developer, although variants of it have been used for some special purposes. Reversal first developers are normally high contrast negative developers, like D-19, with some thiocyanate added as a silver solvent to keep the highlights clear. D-67 is another popular first developer. It is simply D-19 with 2 g per liter of potassiun thiocyanate added. Dektol is fairly close (but not the same) as D-19; diluting it 2+3 and adding thiocyanate may (but only may) work decently.
nworth. Thank-you. I understand the difference between D-94 and D94a. I was only saying that I thought that in place of the DTOD in D94a which is its hypo we could use instead, sodium thiosulfate which is also a hypo when tyring out another substitute developer. I didn't mean to suggest that I thought D94 contained sodium thiosulfate itself.

Anyway, Mr Red's Dektol work suggests that it's a good developer for reversal.

Would you know whether D-19 or Dektol are higher contrast than the PQ Universal that I'm currently testing with?