Re: 3 questions (one of them dumb)

[Richard Knoppow <dickburk@ix.netcom.com>]

----- Original Message ----- 
From: "Diana Bloomfield" <dhbloomfield@bellsouth.net>
To: <alt-photo-process-l@usask.ca>
Sent: Sunday, November 16, 2008 9:16 PM
Subject: Re: 3 questions (one of them dumb)


> I always understood chromogenic prints to be those prints 
> specifically made from color negatives (as opposed to 
> prints made  from color positives . . .  or Polaroids? . . 
> . or from a digital  file?).  I'm surprised, though, to 
> read that calling a chromogenic  print a c-print, is 
> "improper."  Did I read that right?  I always  thought a 
> chromogenic print and a c-print were the exact same thing. 
> If not, I've sure been labeling my work incorrectly for a 
> number of  years now.
>
> Over the summer, I saw the alt process show at Tilt 
> Gallery in  Phoenix, and there was also a c-print included 
> in that show.   Although the print was wonderful, I was 
> very surprised to see that a  c-print was considered 
> "alternative."  I would have thought a  straight b&w 
> silver print to be a whole lot more "alternative" at  this 
> point, than a c-print.  Is it really that unusual for 
> someone to  be making a print from a color negative these 
> days?
   Chromogenic refers to any print, negative or reversal 
(the print I mean) made using a process which generates dyes 
in the emulsion. All modern materials have "couplers" in the 
emulsion which reacts with substances generated in the 
process of development to to produce the appropriate dyes. 
Kodachrome does not contain couplers in the emulsion, rather 
they are in the reversal developers. The Kodachrome process 
is such as to separate the development of the three color 
layers so that the appropriate dye is generated in each. It 
is still a chromogenic process because the dye is created in 
the emulsion by the development process. Kodak resorted to 
using the rather elaborate Kodachrome development process 
because, at the time, they were in a rush to get a color 
film on the market and could not figure out a method of 
preventing the couplers and resultant dyes from wandering 
around in the emulsion layers or between layers. AGFA beat 
them to the punch with this but Kodak eventually came up 
with an alternative method as was used in Kodacolor and 
later Kodak color films.
   Chromogenic films or prints can be either 
positive-negative or reversal, the principle of generating 
the dye as a part of the development process is the same 
although accomplished at different steps in the processing. 
Prints made by the Cibachrome/Ilfochrome process, which is a 
reversal process, are not chromogenic. The dyes exist in the 
emulsion and are destroyed rather than being generated, by 
the development process. Processes where the color is 
applied to the print such as dye-transfer or color carbon 
are not chromogenic.
   Type C is old Kodak terminology for a chromogenic print 
made from a negative, Type-R was the equivalent reversal 
print. The terms got to be well understood and persist even 
though they are pretty old.

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com