Re: Paper negatives- Ink Selection
heh - Change it to what? 2008/10/16 Don Sweet <don@sweetlegal.co.nz>: > I for one am grateful for this informative and useful dialogue. But it's > going to be hard to retrieve in the archives under its present subject line. > Is it possible for to edit the subject line for archiving purposes? > Don Sweet > > > > ----- Original Message ----- > From: "Christina Z. Anderson" <zphoto@montana.net> > To: <alt-photo-process-l@usask.ca> > Sent: Friday, October 17, 2008 2:29 AM > Subject: Re: Paper negatives- Ink Selection > > >> Loris, >> I never get dichromate stain with a 15% solution, even with 5-12 minute >> exposures. >> >> 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. >> >> However, my real reason is to ask why pot di, which only saturates to say >> 10-13% at best, and falls out of saturation if temps fall below 70 >> (something I discussed LONG ago on the list relative to Kosar's chart) > when >> using a 15% am di which would be faster than a saturated pot di and would >> never fall out of solution unless he were working outside in winter I > might >> suppose because am di saturates at 30%? I remember one BJP article >> discussing this very fact that in England back in the day of no central >> heat, the pot di would actually only be about a 5% solution! >> >> I find that people into pot di are dyed in the wool pot diers and people >> into am di can become the same, just because we all build our practice >> around our practice, you know? BUT if long exposures were an issue I just >> don't see why anyone dyed in the wool pot dier wouldn't switch. >> >> What I should really do is just force myself to use pot di for a year and >> see if there is any benefit to it. >> >> Now let's throw another monkey wrench in here for you to test, Loris, > since >> you are fast becoming the expert as you are: at a certain point of >> percentage, am di doesn't produce a speed gain ENOUGH to warrant the >> increased percentage. This is why I settled on 15% tho I used to use 7.5% >> down south where the humidity was always 50% or greater. It's not a truly >> linear exposure thing, such as in the darkroom when you expose a print > half >> a stop more or less you can expect half a stop more or less exposure > (given >> the characteristic curve of paper this is true only to an extent, of >> course). >> >> If I remember correctly, Suzanne Izzo even uses only 5% di concentration, >> and the interesting question is how low a di concentrate you can go and >> still have acceptable times. It's pretty amazing to me, actually. BUT >> again this has nothing to do with Keith's issue of long exposures with > paper >> negs, just a thought I'd throw out there... >> Chris >> __________________ >> >> Christina Z. Anderson >> http://christinaZanderson.com/ >> __________________ >> ----- Original Message ----- >> From: "Loris Medici" <mail@loris.medici.name> >> To: <alt-photo-process-l@usask.ca> >> Sent: Thursday, October 16, 2008 2:52 AM >> Subject: Re: Paper negatives- Ink Selection >> >> >> Using 2A:1B indeed gives a speed gain (w/o any significant quality loss). >> What does it to the characteristic curve of the process I can't say, since >> I never compared... >> >> Keith uses oiled negatives, whereas I don't. But still can get a good >> image and a nicely exposed gum layer (which develops in about 30 - 40 >> minutes, sometimes 60, which can withstand erasing another layer on top of >> it) with only 6:30 exposure. It looks out of the line compared to mine, >> and that's what makes me tend to think that it's something about DR and/or >> calibration. >> >> Full strenght AD would definitely increase speed considerably. But then >> (as a note) I personally don't like the characteristic curve (and results) >> I get with high dichromate. I was using 20% with plain paper negatives, >> then switched to 10% with translucent inkjet bond and the shadow >> separation seems to be better now. >> >> BTW, speaking about high dichromate concentration, comes to mind something >> interesting to mention about dichromate stain: >> >> I was getting dichromate stain (in darkest shadows) with plain paper >> negatives, exposed for 15 minutes, 20% AD. Then I switched to translucent >> inkjet bond, which - according to visible light measurement - is exactly >> 1.5 stop faster than plain paper. That makes 5:20 equivalent exposure time >> (with 20% AD) for the new negative media. I decided to halve the >> dichromate (to 10%) and increase exposure by 1/3 stop to offset the weaker >> concentration (not measured, just was testing if +1/3 stop will be >> enough). Therefore new exposure time became 5:20 + 1/3 stop = 6:40 (which >> was cut to 6:30 later), for translucent inkjet bond, 10% AD. I don't get >> dichromate stain anymore. That can be attributed to the fact that I'm >> giving less exposure to the emulsion, but then I can't explain why I don't >> loose even a little bit of highlight detail using the same negative and >> same development time!? If I was giving less exposure (absolute) to the >> emulsion, then I should have loose highlight detail, don't you think? But >> I don't!? >> >> Could it be not only absolute exposure (the total energy the emulsion >> gets) but also the exposure time does have an effect on dichromate stain? >> (Or what else?) >> >> I'm not claiming anything, just sharing something that confuses me (a >> lot)... Any thoughts? >> >> Regards, >> Loris. >> >> >> 15 Ekim 2008, Çarşamba, 7:13 pm tarihinde, Christina Z. Anderson yazmış: >> > Keith, >> > Have you tried mixing your cyano 2A:1B to cut down one stop? >> > >> > I don't think the 15 min is out of line since I use Pictorico with gum > and >> > a >> > 6 minute exposure. >> > >> > Why aren't you using full strength am di? Or 15% perhaps, instead of pot >> > di >> > to decrease your times, too? >> > Chris >> > >> > >> > Chris >> > >> >> Hi Loris, >> >> >> >> My gums require 15 minutes with oiled negatives. I would really like >> >> to reduce this. Also, cyanotypes made with the same oiled negatives >> >> require exposure times of 30-45 minutes. How does this compare with >> >> others? It seems pretty long. >> >> >> >> Keith >> > >> > >> > >> >> >> >> > >
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