Quote Originally Posted by Alan Johnson View Post
I have done some testing of PC-TEA where the developer is dilute but quite high amounts of sulfite added and I could not get grain as fine as Xtol(or DS-10,Mytol,E-76).It seems to me quite likely that the high phenidone(or derivative), ascorbate and borate in these latter contributes to the fine grain.Therefore the concentrate has to be high in phenidone,ascobate and borate.The chemistry gets to the limits of what is known,esp wrt the formation of glycol borate complexes and their dissociation,when making these concentrates.It's quite a project.
My experience agrees with Ryuji. As an example, here's a formula that gives grain matching XTOL under my 22x loupe, yet has low concentrations of phenidone and other components. This formula is for a concentrate yielding either 5 liters or 1 liter of working solution:


Working volume ----------> 5L .......... 1L
Propylene glycol .............. 75 .......... 15 ml
Sodium metaborate ......... 11 .......... 2.2 g
Ascorbic acid ................... 22.5 ....... 4.5
Phenidone ....................... 0.25 ....... 0.05 g
Propylene glycol to .......... 100 ........ 20 ml (should need to add only 5/1 ml)

pH = 8.0. Use 20ml per liter (1+49 dilution) into water containing 45 g/L sodium sulfite.
Develop for twice XTOL's times.
I tried this developer for the first time yesterday, and the TMY-2 test-strip looks great. The appeal is that it uses only half the sulfite as XTOL, less other chemicals, and can be concentrated to 1+49 dilution. Of course, one must develop for twice as long, but for me, that 7-minute cost more than compensates for the benefits. This formula is similar to diluting XTOL 1+1, but with less phenidone, more buffering and a lower pH to avoid the reduction in contrast. So I'm going to tweak and test this formula some more.
Anyway, it shows that low concentrations can produce grain as fine as XTOL.

My potassium sulfite and dimezone-s are here, so I need to try those out. Man, there's too much to do! Gotta stay focused...

Mark Overton