U of S | Mailing List Archive | alt-photo-process-l | Re: Paper negatives- Ink Selection

Re: Paper negatives- Ink Selection

Loris said:
10% AD is about equivalent to saturated PD, which is something like 13% at
room temperature. PD solubility in 20C / 68F is 12% (according to MSDS),
at 22C / 72F (room temperature) should be slightly more (about 13%,
AD molar mass = 252.07g, 100 (10% in a liter) / 252.07 = 0.39M
PD molar mass = 294.19g, 130 (13% in a liter @ 22C) / 294.19 = 0.44M
and 120g PD (12% in a liter @ 20C) / 294.19 = 0.40M
Accepting there isn't any factor affecting speed (chemically) other than
molarity of dichromate ion in solution(!?), then in theory, due to
slightly stronger concentration (0.44M > 0.39M), 13% PD should be slightly
faster than (or about equivalent to) 10% AD.

Chris says:
Thanks for this again, Loris; will file it in my "to know" file. My next "to do" for education would be to take a series of chemistry classes so I can understand what the hell molar mass is, but it looks good to me!

Loris said:
What a pity! For how long it will stay? Good luck in rehabilitation...

Chris says:
Well, what was supposed to be 10 days ended up being 6 weeks when I awoke from the operation. So you can imagine how grumpy I am. Can you imagine having to have your husband drive you everywhere? Well, no you can't, it'd be your girlfriend...But it has been a great experience because I am VERY understanding now of people's "minor" surgeries which are only "minor" to others (and also student absences due to surgery--I actually missed a week of school for the first time in my life).