[pure-silver] Process control (was Re: Re: Agitation and contrast)
- From: Dana Myers <dana.myers@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Mon, 25 Nov 2019 10:38:24 -0800
Following-up on my own note:
On 11/12/2019 9:52 PM, Dana Myers wrote:
On 11/12/2019 9:04 AM, Robert Shanebrook (Redacted sender makingkodakfilm for
DMARC) wrote:
Keep it simple:
Use time-and-temperature to control contrast/density. Yes, T-Max Films are more sensitive to time-and-temperature
differences than 3D films. T-Max Film development time differences of +/- 15 seconds are enough to make a difference.
For 3Ds 25% is an appropriate difference.
I was just amazed to be reminded just how sensitive T-Max is. Not a bad thing,
just a thing to manage. Way back when, I'd use a Coleman as a water bath
to stabilize temperature, but then I became perhaps a bit lazier and started
adjusting processing time to match temperature, processing between 70F
and 75F depending on the time of year. J-109 gives times for 70F and 75F,
and I've been linearly interpolating over that range.
After writing this, I thought to review my process - specifically, I usually
use stainless daylight tanks/wire reels, mix Xtol 1+1, measure the temp
of the developer and go from there. It occurred to me that the tank/reel
has some influence over the temperature of the developer, so I dumped
spent developer into a plastic cup and measured it. I did this a few times
and found that the developer was warming-up ~2 degF while processing.
This didn't happen back when I used a water bath, of course.
Oh snap. No wonder my T-Max negs still had a bit more contrast than
desired/expected. Linearly interpolating between 70F and 75F, it's
about 18 seconds time per 1 degF - over 30 seconds difference!
Enough processing talk, here's a snapshot from yesterday's dog walk,
400TMY EI320, Xtol 1+1, exposed in a now-vintage Canon EOS Rebel G with
the very pretty EF 50mm 1.4 prime. (it's a quick scan, please ignore the
dust/fiber):
https://drive.google.com/file/d/1qVK6ztr3rw-cHMCJwU4UUxv1YiZWd2B7/view?usp=sharing
Cheers,
Dana
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