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Topic: JOHN WHITTLE ... Please Help!!
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Osi Osgood
Film God
Posts: 10204
From: Mountian Home, ID.
Registered: Jul 2005
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posted March 28, 2008 10:23 AM
I always had this wild idea, (and still, sometimes tempted to do with a piece of unwanted scrap film) of creating a tank of whatever dye seems to have disappeared on the film, (for instance, blue), but I always needed someway for the dye to permeate the film, and that agent escapes me, but if I could figure out the agent to allow "permeation" of the film, I might have a go at it.
-------------------- "All these moments will be lost in time, just like ... tears, in the rain. "
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Osi Osgood
Film God
Posts: 10204
From: Mountian Home, ID.
Registered: Jul 2005
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posted April 01, 2008 10:29 AM
Hey John, another question that occured to me ...
Would different film stocks respond differently,to different approaches, or perhaps, different solutions ...
... or, are film stocks fairly "universal" in chemical approaches?
I ask as, perhaps my Kodak SP would respond better to chemical color reversal, than the dreaded Eastman color stock. Perhaps that mid 70's Eastman stock, (which tended to fair much better), would respond better as well?
Any thoughts John (and others)?
-------------------- "All these moments will be lost in time, just like ... tears, in the rain. "
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John Whittle
Jedi Master Film Handler
Posts: 791
From: Northridge, CA USA
Registered: Jun 2003
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posted April 03, 2008 05:22 PM
Kodak originally used different couplers and developing agents from Fuji and Agfa. Eastman used CD-3 for Eastman color negative and Ektachrome, CD-2 for Eastman color positive. When the patents expired in the mid-70s on these chemicals, Agfa and Fuji introduced stocks that used the same processes which made if possible for a lab to use any of the three color positive materials in a single processing machine. Agfa Gevacolor and Gevachrome used a totally different suspension system and a different color developer and coupler.
This does not mean that the dyes used in the various stocks was the same. Agfa used a different cyan dye and since it had a better absorption in the infrared spectrum, it made a better optical sound Super8 print that Eastman material.
And dyes were changed with various stocks (5282/7382, 5385/7385, 7380, etc) in both the Eastman line and Agfa.
There were also various suppliers of chemicals and labs could buy from Kodak (for CD-2) or Hunt (for Code-2) for color developers. I don't know of any research or any record keeping that would allow us today to track chemistry against fading.
There are just so many variables from so many labs that we'll never know for sure if one is more stable than another.
What we do know is that films that have no resuidal couplers in the emulsion have much better keeping qualities. These are Technicolor IB prints which were dye transfer and Kodachrome which had the couplers in the processing baths and not in the film. The dyes in Kodachrome and processng also changed over the years (as did the film base which was different than that used for Eastmancolor) so there can be differences between a Kodachome from 1940s, 1950s, 1960s into the 1970s. The films also got faster, finer grain and sharper over the years.
John
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