[pure-silver] Re: Developing Kodachrome
----- Original Message ----- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, June 22, 2009 7:08 PM
Subject: [pure-silver] Re: Developing Kodachrome
----- Original Message ----- From: "Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, June 22, 2009 10:14 AM
Subject: [pure-silver] Re: Developing Kodachrome



"Martin magid" <martin.magid@xxxxxxxxx>
I was recently given some 35mm Kodachrome dated in the mid 1980s, 
supposedly frozen all that time.
There is a good chance it is still usable - try a roll and send it 
off to Dwayne's.
I just ordered my last brick of K64. Figure if Dwayne's stops processing it at the end of 2010 I have to shoot a lot of slides ... 

Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121
I concur with this, I am pretty sure the current process is the same as used in 1980. At least contact Dwayne's and ask about it. Kodachrome processed as B&W has the problem that the yellow filter layer can not be removed. In Kodachrome this layer is composed of colloidal (very fine) silver. It is normally removed in the last bleach step where all the silver is removed leaving only the dye images. It is possible to print with the yellow layer but its likely you will have to make a diapositive on panchromatic film and a duplicate negative from that. Because the filter layer is such finely devided silver it is possible that a very mild silver bleach will remove it without affecting the image silver too much. Such a bleach can be made from film strength rapid fixer by adding about 15grams/liter of citric acid to it. 

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
I realized on re-reading this that it isn't quite true. You can reverse Kodachrome without using the color developers and using a standard reversal process. When that is done the bleach step will remove the filter layer. Normal reversal processing has the following basic steps: 

1, Develop to a negative.
2, Bleach out the silver image using a bichromate or permanganate bleach. This removes the metallic silver but leaves the silver halide. This step should remove the yellow filter layer. 

3, Ckearing bath.
4, Fog the remaining halide, either by exposing to strong light or using a fogging agent. 

5, Reversal development.
There are, of course, some intermediate rinsing steps etc, and generally a final fixing step is used to eliminate any halide which escapes the preceeding processes.
Some experimenting would be necessary especially for the first developer. In reversal processing the first development is generally carried out to a quite high contrast. In addition some halide solvent is usually added to the developer to prevent veiling of the highlights in the final, reversed, transparency.
The actual Kodachrome process is quite complicated since there are three reversal developments, each with a developer cotaining the appropriate coupler, plus many intermediate steps.
Someone stated (maybe this was in a press report, they always scramble things) that Kodachrome had the advantage of the recoverability of all the silver in the emulsion. Actually, this is true of all current color processes.
As far as there being only a very small market for Kodachrome I think Kodak helped to create this by making processing difficult to obtain in the first place.
I think Kodak became oriented to mass production on a very large scale and never had the knowledge of how to produce on a small but still mass production basis. Perhaps its not possible. 

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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