It should be easy enough to make a suitable substitute from basic components.
Kodak D-25 can be used at a temperature of 25*C and the suggested times are those given for Kodak Microdol-X when used at 20*C.
750ml of water at around 50*C
Metol = 7.5 grams
Sodium Sulphite, anhydrous = 100 grams
Sodium metabisulphite = 15 grams
Water to make 1 litre.
I don't believe Microdol-X contained a mercapto compound. It contained a weaker type of anti-silvering agent. Perceptol is virtually identical in its working properties. I'd go with that over a home mix.
D25 is not the same. It achieves finer grain than D23 through a decrease in activity (lower pH) which means more solvent action. Think of it as D23 but with longer development times so that the sodium sulfite has longer to work on etching the silver grains.
Microdol and Perceptol are different. They are essentially D23 with the addition of sodium chloride to give finer grain.
It is also not clear how much Metol is in Microdol or Perceptol. Most people assume it to be 7.5g/litre because that is the most common amount used in D23. However this is not necessarily the case, and there were/are other versions of D23 with different Metol concentrations, such as 5g/litre.
Michael, we had a huge discussion about this with PE many moons ago, and yes there is a mercapto which remains a trade secret. That much I was able to ferret out off that crafty wizard. I'd suggest a search but most times that doesn't find the relevant post. I think it was 'Microdol-X replacement".
To me, MDX has an ever so slightly smoother tone when used 1:0 and slightly more brilliance when used 1:3 as compared to Perceptol and D-23/25. Teeny tiny.
I've never seen a version of D23 with 5g/litre Metol but then I don't use the Photo Lab Index data or most US books that perpetuate their misprints either.
Originally Posted by Michael R 1974
All the major manufacturers have their specialist compounds that help prevent Dichroic fog, Agfa discovered and Patented their first in the 1930's a spin off from testing long chain non foamingwetting agents nto add to packaged developers. Ilford, Agfa, Fuji etc as well as Kodak hold Patents for these types of compound.
There's a version of D-23 in a BJP annual in the formulary section which uses 5 grams of Metol and 100 grams of sodium sulphite, anhydrous per litre of stock.
The formula is called Ferrania R-33.
Thanks for pointing that out. I'm definitely not going to argue with PE when it comes to Kodak :). I was under the impression the anti-silvering agent in Mic-X was not a mercapto compound. My primary source for that was Anchell/Troop but now that I think about it in Anchell/Troop there was no definitive answer on what the secret ingredient was.
Originally Posted by RidingWaves
I used a lot of Microdol-X and later used a lot of Perceptol and in my testing I never saw a difference at either 1+0, 1+1 or 1+3. That's just me though. Substituting for Microdol-X I'd still go with Perceptol vs D25, which did look different to me.
Yeah, when I finally run out of both Microdol-X and the Microdol-X replenisher (whew! THAT stuff lasts and lasts) I'll use Perceptol. Luckily I have a small supply that should last a few years, but lately I've been taken by DK-50!!!