Re: Paper negatives- Ink Selection
"If Keith were to increase his dichromate from pot di full strength to am di full strength, yes the curve changes and I assume he would recalibrate to make a curve for full strength. But if I remember, Keith is fairly loosey goosey about his practice and produces excellent work so he may not need to." While I do feel better that I am throwing less toxic chemicals into the environment by diluting the sensitizer, in actuality, I am not so much "diluting the sensitizer" as "thinning the emulsion" so that it will spread easier. As I think I have discussed before, I like to humidify the paper prior to coating to make it less "grabby". Masa doesn't work that way. In an interim step between humidification and thinner emulsion, I was spraying the surface of the paper with water. Since I was diluting it anyway, as a move towards More Consistancy and Less Loosey Goosey I just added the water to the mix. I'll try am di and see what that brings. If I recall, it is a bigger hassle to obtain am di. More hazardous maybe? On Thu, Oct 16, 2008 at 8:36 AM, Christina Z. Anderson <zphoto@montana.net> wrote: > 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%, > empirical). > 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). > Chris > > > > >
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