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

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
>> >
>> >
>> >