Ouch! This hurts!

[John Layton]

Paul that's a beautiful image - and that test is meaningful to a degree...but there are some differences - specifically apparent print color and brightness/contrast, which you could likely manipulate further in the PMK image to bring it a bit "closer" to the Thornton 2-Bath image.

My gut says you can get them closer...but that the Thornton image would still have some qualities (high value smoothness and delicacy) which makes it very special. Its been a long while since I've souped in any sort of 2-bath soup...and your image inspires me to give this another try! Thanks!

[Michael R]

Yes, D23 in general relies on a lot of solvent effect. There might be a way to tweak it with sodium chloride to improve acutance; but I've never tried that.

Sodium chloride would increase solvent effect - that's what Microdol/Perceptol use in addition to sulfite.

In any case, these divided metol-sulfite developers will generally all do the same thing unless the differences in formulation are massive. The Thornton versions are superfluous. Adams is functionally identical. Actually you don't even need metaborate. The Stoeckler formula with borax in the second bath does the same thing. One could also use a Perceptol first bath with borax or metaborate second bath. The concentration of alkali in the second bath makes no difference as long as you have at least a few grams.

One thing this type of two-solution development tends to do from a sensitometry/tone reproduction standpoint is give a somewhat straightened curve - ie short toe and long straight line with little shoulder. Some people prefer that linearity for negatives destined for scanning/digital editing.

[paulbarden]

Paul that's a beautiful image - and that test is meaningful to a degree...but there are some differences - specifically apparent print color and brightness/contrast, which you could likely manipulate further in the PMK image to bring it a bit "closer" to the Thornton 2-Bath image.

My gut says you can get them closer...but that the Thornton image would still have some qualities (high value smoothness and delicacy) which makes it very special. Its been a long while since I've souped in any sort of 2-bath soup...and your image inspires me to give this another try! Thanks!

Thanks!
RE point 1) Yep, I agree - my test is of limited utility and only somewhat meaningful. So many variables, so many ways of interpreting a negative.
RE point 2) It's mainly the high value rendering I find of value (to me) with the 2-bath negative. Grain structure and sharpness don't matter a while lot, since my 8x10 negatives are created primarily for contact printing. But I've observed this effect with divided developers before, and they do seem to impart something special as regards the tonal scale and value separation/luminosity.