Certainly nice to see you back on the list. I will echo your advice and
that of Luis to keep the variables in carbon printing to a minimum and to
start with a known negative of good printing quality, i.e., with a long
density range and, in the words of old, very stout. The wonderful thing
about carbon, however, is that with experience excellent prints can be made
from many different types of negatives, from negatives that would print on
silver at grade #0 or #1 to others that print on grade #4 or #5.
Paper negatives are still an attractive and inexpensive alternative to
continuous tone film (or digital negatives) for carbon negatives. The down
side is that they require very long exposures. The Base plus Fog for most
films will be .20 or below, while for paper negatives it is typically of an
order of .80, a log difference of .60, or two full stops. This translate to
exposure times that are 4 times as long as with film. In my working
conditions exposure with film negatives average about 6-8 minutes, with
paper negatives 24-32 minutes.
Finally, I wonder what problem you have had with food gelatins in the
making of carbon tissue. I am aware of quite a number of folks in the USA
who get excellent results with a food gelatin sold here under the brand
name Knox. I have also used it occasionally to good effect.
Sandy King
>Nachricht geschrieben von Wayde Allen
>>The resulting carbon print was also too soft, but I'm certain that I
>didn't have enough pigment in the tissue. I was experimenting to see how
>little pigment I could get away with. Will probably mix up a new
>batch tonight to continue tinkering.<
>
>After doing carbon printing for many years now I can only recommend to
>beginners - as Luis and others allready did - to start with the smallest
>number of variables possible.
>
>-Get Luis Nadeau's book Modern Carbon Printing. Or try to get A. M.
>Marton's "A New Treatise on The Modern Methods of Carbon Printing,
>Bloomington, Illinois 1905" There should be a copy in the
>George-Eastman-House library or the Rochester Institute of Technology
>library.
>
>-Get a good continous tone negative with a density range of ca. 0.2 to 1.7
>logD or a little more. Paper negs are likely to be underexposed, as they
>are usually juged by reflected light first. I found it surprizing to see
>how dark they must be printed in order to give enogh detail in the shadows.
>At the beginning, I would strongly recomend to have the negative density
>checked with a densitometer. "Contrasty", "dense" etc. means different
>things for most of us.
>
>-If you want to start with a self-made tissue, start with one of the old
>formulas, prefereably one that doesn't recommend too many ingredients and
>use photographic grade gelatin. Food gelatin is too soft. Don't change
>these formulas and working schedules until you get consistent results. It
>is more likely that the old (and new ;-)) writers knew what they were
>writing about than that they are telling us nonsense. Of course they don't
>tell us all we would like to know as for them many things went without
>saying...
>BTW: I still have original Hanfstaengl tissue in two colours (olive black
>and violet black) here for sale.
>
>-Start with a 2-3% potassium dichromate sensitizer. As it is likely that
>you are still working slowly at the beginning, I would suggest to add
>ammonia to this solution until it turns yellow. This is the only additive I
>found of any advantage, as it slows down the sensitivity and improves the
>tissue's keeping properties considerably. If your prints are coming out too
>soft or contrasty, change the neg, not the sensitizer... I also found the
>classic soaking for three minutes in cold sensitizer (15-17C) to be better
>than applying sprit sensitizer with a plastic foam brayer - although the
>latter method just needs 25 to 50 ml of sensitizer...
>
>I do not store the (used) working solutions for more than one or two days
>but only the saturated stock solutions. Regarding your waste water: It is
>likely that the dichromate will form less- or non-reactive compounds on
>it's way down the drain to the clearing station, when it gets mixed with
>other industrial or privat waste water. I was told by specialists that
>pounds of pure dichromate poored right into the bassins are necessary to
>kill the bacteria in a modern water clearing station for a city with appr.
>100.000 inhabitants. However if you are unsure or close to a small clearing
>station don't play roulette, let the solutions concentrate by letting the
>water evaporate and give it to a save disposing company for toxic waste.
>
>-Fixed-out bromide paper or even RC paper is o.k. to start with as single
>transfer paper and for test strips. Try the matt versions - it is just nice
>to see the glossy relief on it.
>
>Klaus Pollmeier