I SHALL NOT WANT...
DEAR LIST, My kitty litter buckets runneth over! At Eric's prodding I finally bought a 55 lb bag of oxalic acid and a 50 lb bag of potassium carbonate, the smallest quantities I could get over 1 lb at a time. As they come in flimsy bags I am storing them in old but clean kitty litter buckets with tight lids. Sooooooooooooo, I shall not want for Pot Ox PT/PD developer! However, here are some qualitative comparisons between paper (Cranes Platinotype) coated and exposed exactly the same but developed in my former favorite, sodium citrate dev, and the pot ox dev. Same neg, coating chem same, re-humidification process same, dev temp same 40 C, everything the same except the devs: 1) Pot ox gives more contrast. 2) Pot ox gives a little more speed. 3) Pot ox definitely gives a warmer print color. 4) Pot ox compresses the shadows, i.e. they go to a solid black with less separation even when highlight densities of prints in both devs match. *********Next, I will coat some paper, cut it into test strips, expose them in my Nu-arc with the same step tablet, process them identically except for the dev, read reflection densities with my X-Rite, and plot D-logE curves. I will do a sample size of at least two for each option. If there is, indeed, a compression in the shadows, this should be obvious in the curves. I will report results when I (finally) get around to doing this. CHEERS! BOB
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