Hi Paul,

I see what you mean about there being similarities between formula; they are all using the same components for the most part. I wouldn't say they have identical quantities, though. Dupont LD-1, for example, has less paraformaldehyde than Kodak D-85. That's going to have an effect on the working solution's alkalinity, won't it?

I wish I could find the source - I dug through all my books in the darkroom - but I remember once reading that an optimal alkalinity for hydroquinone was ph 12. In one of the formaldehyde free formulas that Ryuji Suzuki posted ("Burning Lith Developer") he used a 1% solution of Trisodium Phosphate as the alkaline, giving it a ph of 11.3% (as per the darkroom cookbook - I don't have a ph meter). I assume that was a good working alkalinity for hydroquinone. I was hoping to determine an optimal dilution by keeping things like that in mind. Does that make sense? Maybe not!

It's harder to understand that relationship between paraformaldehyde and alkalinity. I gather that it converts sodium sulfite to sodium hydroxide, which is pretty ingenious. To what extent, I don't know. Maybe a chemist can chime in.

If you ever dig up that spreadsheet, I'd love to have a look at it! Formulas aren't that easy to come by. There's Rudman's 2nd book, the Unblinking Eye site, and this fellow as well. There are a lot of repetitions, for sure.