Kevin O'Brien (kob@paradise.net.nz)
Sun, 14 Mar 1999 23:08:16 +1300
>Kevin, some questions in response to your suggestions,
>
>-I have found that after a 2-3 minute still water developing, the hypo
tends
>to have no further influence on the brown tones, and actually, it begins to
>bleach the images quite quickly. I will dilute my hypo further, but in your
>experience, how long should the image stay in the hypo?
Use 'fairly fresh' hypo 2½%. Once the colour change finishes, I believe, its
done. Anything extra only bleaches.
>- your point #7a After quick wash blot dry: what means quick? My
>understanding is that the final wash, using papers, should be between 30-40
>minutes with running water. One of the variables I suspect in the failure
>of my first tests was not enough washing (and washing face up, so that the
>excell solution couldn't wash off, but rather soaked right back into the
>plaster). So, how quick?
My only notes about the final wash refer to the paper negs made that way
getting a 'quick wash' . From memory that would have been about 2-3mins.
Regular tap water was used and I think they rinsed in a tray with a few
changes of non-running water; the prints got several more changes but their
wash time is unlikely to have been more than ten minutes. I was concerned
about the image being on the surface. I may have used the standard Kodak
formula hypo eliminator. I normally take care to keep processing
temperatures fairly constant at about 20C so would have considered that too.
The prints show no change after 17 years so perhaps I got it right.
>- thank you for reminding me that I have alternates to a densitometer! I've
>got a meter and a light table, and fairly close to my inkjet printer, great
>tip
>Also, I am using a fairly old vandyke solution (about 2.5 years). I
strained
>the precipitants, and the solution is not all that contrasty. I will try
>increasing the contrast once I've achieved a succesful method of printing
>and fixing (with Keepers of Light suggested potassium dichromate), and once
>I've printed the best negs possible. During exposure, the solution slowly
>changes from a faint yellowish to a more intense greeny-yellow. Can you
>describe the action of your chemistry during exposure more fully?
>
I usually make fresh solutions for everything just before use. Its's easy to
do by keeping suitable stock solutions and taking the little of each as
needed and making up with tap water or deionised water if needed. Fresh
solutions make for repeatability.
The contrast problem I suspect is TOO MUCH SILVER. Lately I have seen some
very complicated brews but mine was a simpler version from Nettles, which I
think from her citation, may have come from Kodak. The silver nitrate was
given as 37.5g or 1oz bottle and this was to make up 32 fluid oz of working
solution. My Scot's part chose the 1oz, called it 25g, and used that. The
effective recipe was:
Ferric ammonium Citrate (green) 90g
Tartaric acid 15g
Silver nitrate 25g
Distilled water to 900ml
The original method suggested dissolving each ingredient in 300ml, combine
the first two and slowly add the silver nitrate. I made it up by dissolving
the citrate and nitrate each in 400ml of distilled water and prepared a 25%
soln. of tartaric acid. The following then gave approx. 50ml of fresh
working solution:
Ferric ammonium citrate 22.5% soln 22.5ml
Tartaric acid 25% soln
3.3ml
Silver nitrate 6.25% soln 22.0ml
This concentration gave very dense darks: contrast and tonality was no
problem. It could be reduced by too much 'development', fixing or final
washing. Also by a bad choice of paper, a second coating or exposure beyond
the point where the highlights in the negative just printed. Once the
maximum density had been attained at the printing out stage any further
exposure reduced the contrast. No additives were used for contrast control
nor were necessary. It is understandable with a printing out process with
integral masking that a coating thicker than optimal will interfere with
correct exposure. I am sure that this is why the surface sizing is important
too as it indirectly regulates the coating thickness. This explains the
variability amongst the different papers used. The Pd/Pt process is probably
similarly sensitive to coating density. A bonus is that it also costs less.
Coating was done by red safelight as the yellow-green shows up well. A soft
wide cheap brush with soft short hair was used. It was rinsed well to wet it
out before commencing coating.
The image colour could be darkened to the point of blackness by holding it
in front of a heater. It could be bleached with a permanganate/sulphuric
bleach which changed the colour of the print to more blue with a weak alkali
bath subsequently to neutralise the acid. I haven't tried other toning.
Kevin O'Brien
>thank you,
>more updates later.
>Cheers
>Risa
>
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