[LargeFormat] Brownish stained negative

[rstein]

Dear Thomas,

     Did you develop the sheet of film in the Nova tank system that you
bought? I ask because I recently solved a difficult problem with prints that
sounds similar to your rusty negative.

     Briefly, I noticed a discolouration on 8/10 and 12/16 prints that also
sat in the center of the print - a sort of a browny yellow tint that had
indefinite edges but was at least 5-10 CP units in strength. The top 1/3 of
the print and the bottom edge was normal colour.

     I initially blamed the condenser in the enlarger - then the small
colour head that I had attached to the top of the 4 x 5 housing - then the
size of the colour filters that I substituted in the drawer when i converted
back to tungsten lighting and the condenser. I bought a set of larger
filters on the strength of it and thought I had cured it but back it came.

    Not present on test strips - just full size prints.

    Then I sat down and thought - it was present on 4 x 5 negatives as well
as 6 x 6's - these two negs use different amounts and areas of the light
beam so it really shouldn't be exactly the same. And two 6 x 4 prints
stacked onto a sheet of 8 x 10 paper with identical exposure showed that the
bottom one of the sheet was being affected by the stain but not the top one.

    So I suspected the Nova tank. I had not had the problem at all when I
was using the 8 x 10 Nova Quad but the new 12 x 16 Quad did it. My agitation
action for the 8 x 10 was up and down but for the 12 x 16 was side to side -
more room to do it, you see.

     THAT WAS IT. Somehow down in the depths of the 12 x 16 at about 8
inches there is a stratification of chemicals or agitation action going on
that affects the print. When I changed to an up and down plunging or
swooping action on the paper - the stain disappeared - I can now get clear
whites and neutral greys evenly down the whole print - including 12 x 16.

     Could you also have a stratification of a slightly used fixer?

     Of course, if this was dish or tank development it all goes out the
window - but beware the agitation in the Nova.

     Uncle Dick

PS: The new secondhand Jobo CPE 2 Plus has just finished the first colour
run and it looks like it is a success. Odd sitting there just pouring things
in and out.