U of S | Mailing List Archive | alt-photo-process-l | Re: carbon transfer (mainly: digital negatives)

Re: carbon transfer (mainly: digital negatives)

My Carbon process Transfer



----- Original Message ----- From: "phritz phantom" <phritz-phantom@web.de>
To: <alt-photo-process-l@usask.ca>
Sent: Monday, March 30, 2009 2:01 PM
Subject: carbon transfer (mainly: digital negatives)

after a few weeks of trying, i finally get more or less acceptable
results. now it's time for the fine tuning.
i think most of my problems lie in the preparation of the digi negs. i
read in the sandy king article that carbon needs a more contrasty neg
that gum, so i printed a few small ones with the "strong contrast (rgb)"
preset of photoshop.
not the best of ideas, because it has too little shadow density. the
areas of the negative that have good density are those that print rather
well (f.e. the side of the car in the pic at the bottom), but the thin
areas are those that trouble me.
i have the same problem with gum occasionally. even though the contrast
range is not big, the dark areas often lack detail. how do i get more
guts in the shadows? alternativephotography seems not to have a curve
suggestion for carbon? how do you treat your images before printing?
curve or straight?

on a related note:
is it possible that photoshop loses shadow detail when inverting an
image? scatterbrained as i am, i often forget to invert an image before
printing it. this happened again a few days ago. so i printed the same
images again, only inverted. and compared there is definitely more
detail in the shadows on the positive on film than in the neg on film.
for example the stacked wood in the second pic, in the shadow part i can
see a little detail (very faintly the pattern of the ends of the logs),
while the same area in the negative on film is completely blank.
my guess is that the printer can't print those very faint areas, so they
just get lost between photoshop and printer.

my last problem is that there is some kind of fogging, that only seems
to happen in the densest areas of the print. it's clearly visible in the
two scans (actually it's more visible than in the original). i think it
has something to do with the warm water development. i think the excess
gelatine comes off the shadow areas first and later off the lighter
areas, so those dark areas are exposed to the warm water longer than the
light areas. so more pigment floats off and these cloud-like grey areas
are produced.
i already tried raising the temperature of the warm water bath to get a
quicker development. i used appr. 50°c (120F) in the second pic (the one
with the stacked wood), the grey fog is less, but not completely gone.

and regarding relief:
if i want to have a more relief in the final print (i have pretty much
none right now - at least nothing tactile when sliding my finger over
the print). the clue to relief seems to be a thicker tissue. but does it
also mean, that i'd have to expose longer?

the two prints:
both are on homemade tissue (glop: 20gr rabbit skin glue + 15gr sugar +
3.5gr lamp black (powdered) + 250ml water)
spirit sensitized with: 2x 4ml per 8x10 (20ml acetone + 20ml 2.5%
dichromate sol.)

exposure: 1:30min; 2 min soak; 19 min press.

exposure: 1:50; 2min soak; 27min press. the one with the increased temp
in the warm water.
(contrast is way off in this one)
both images are still inverted because i'm heading for double transfer.

any ideas for improvement?

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