The exception for me was some obscure Spanish a paper I found last year. I was interested in making large prints 16x20" but new paper is expensive. I took a chance on one box and got pretty good results. There is some light gray fogging in the white borders however. In another post I experimented using Potassium Ferrocyanide bleach to rescue some old and very fogged Agfa paper. This was met with some success but it was a simple experiment.
Now that I have The Beast I have been itching to make some more big prints from 4x5 negatives. Prints from medium format negatives are acceptable at 16"x20" it is the upper limit I suspect for most people. Nerga Portrene is my paper of choice due in part to the price but I also love the paper. The blacks are very black and the texture is very warm and creamy though the emulsion is not warm at all. If I could improve the fogging then it would be even better.
The experiment I performed is simple. Develop an unexposed strip of paper and a fully exposed strip (White and Black). I then drew parallel lines across the back of the paper at equal intervals. I then dunked each strip into the pot-ferri solution up the to the first line for one minute. Then pushed the strip in up tot the next line for another minute. This continued for 5 minutes so the first strip was bleached for 5 minutes up to the next line 4 minutes etc. I did this for both white and black test strips. I wanted black to see when the bleach would impact the black as well.
My pot-ferri working solution is 1+10 of my stock solution which is a Fotospeed formula. I will fix separately. Dilution is important as the stock solution works very fast.
In the following results the bottom part of the strip is the unexposed developed section. This illustrates the fog. The marks running to the top showing the bleaching interval. I enhanced the photo to make the gradations more apparent. There is noticeable fogging at 1 and 2 minutes and I think at 3 minutes. So the best bleach time is probably between 3 and 4 minutes. I did the same for the black strip and cannot discern any change all the way to 5 minutes. This is good news. It is probably worth making a gray-scale test strip with half stop exposures and bleaching half at the same intervals. This would inform any impacts on tones.
|Bleach test strip.|
|Bleach test strip|
Now I try different prints to put this too the test. I bracketed the test with two exposures, one at 11 seconds f11 and the other at 22 seconds f11. These are both unbleached.
|f11 11 sec Negra contact print|
|f11 22 sec Negra contact print|
|f11 22 sec Negra contact print 3 min bleach|
I later made a full size print (16x20) in which the 3 minute bleaching worked to greatly improve the contrast.
I tried the same print on new variable contrast Foma 123 paper without bleaching and got what I think were inferior results. The Foma VC paper never seems to deliver a deep black for me. I did get better result with Selenium toning (1+3) but also got an magenta tone which some might not like. The toning did deepen the blacks.
|Toner Test Bottom: None Middle: Selenium (1+3) Top: Moersch Iron Blue|
Foma 123 f11 #5 16 sec #0 0 sec