[pure-silver] Re: Modified Agfa 108 with multigrade paper
- From: Georges Giralt <georges.giralt@xxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 15 Mar 2007 20:52:23 +0100
Hi !
I can't answer you about the way to increase contrast into the paper
without a hard contrast filter.
But my understanding is that if you experience lighting unevenness at
high grade setting with your light source/negative combination, this
will show if you increase contrast chemically or optically. It is the
seep curve of the high contrast paper that make unevenness in lighting
obvious, no matter how you get the curve. (a tiny Delta e makes a huge
delta d if the curve is nearly perpendicular to the horizontal axis...)
Hope I'm able to explain clearly enough with my less than perfect English.
Last but not least, multigrade paper is made of 2 or more emulsion
layers, of various contrasts each one being color sensitized. If you use
white light, you give an equal exposure to all layers and this result in
an mid range contrast. I wonder if you can chemically affect this response.
I had luck with my Durst enlarger when trying to even the lighting by
inserting a frosted glass between the light bulb and the condenser,
increasing in huge amount the size of the light source seen by the
condenser set. it could be worth trying with a sheet of drafting paper.
YMMV ;-)
hksvk a écrit :
I have the following formula for Agfa 108 paper developer: metol...5
grams/liter, sodium sulfite...40 g/l hydroquinone...6 g/l potassium
carbonate...40 g/l potassium bromide...2 g/l
I have tested this Agfa 108 with Ilford multigrade fiber paper without
(for reasons detailed below) a polycontrast filter , but find that my
prints need more contrast than this already high contrast developer
provides. So, in an effort to gain contrast, I have modified the
developer as follows: reduced metol to 2 grams/liter, increased
hydroquinone to 14 grams/liter, and, for the accelerator, substituted 4
grams/liter sodium hydroxide for the potassium carbonate.
Having seen no substantial gain in contrast with these modifications, I
then increased the bromide in 1 or 2 gram/liter increments until
reaching 10 grams/liter potassium bromide. Still, I am seeing no
appreciable increase in contrast.
Is there something about modern paper emulsions that makes them
unresponsive to these strategies to increase contrast? Or is this
problem due to some property of the multigrade paper? Would a modern
graded paper respond to these manipulations?
The 2.25 inch square negatives I am printing from require absolutely
even edge-to-edge and corner-to corner illumination from the light
source of my Beseler 4x5M series enlarger with condenser head and PH212
lamp. With no negative in the glassless negative carrier, when I expose
a sheet of the 16x20 paper at a very low density (zone 8 or so), I get a
pattern of increased density, even after improving the unevenness of
illumination that I encountered initially. The polycontrast filter that
I would require (3.5 or 4) exaggerates this unevenness and makes it too
apparent when printing from the negative. These negatives are extremely
nerve-wracking if not impossible to dodge and/or burn in.
I know, one solution would be to produce a set of more contrasty
negatives, but this would be very difficult to do.
Is there someone on the list who could kindly help me with this problem?
If a graded paper might work for me in this situation, is there one that
could be recommended?
Many thanks.
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