[ARC5] WW II Aircraft factory pictures

[Richard Knoppow]

----- Original Message ----- 
From: "Bob Macklin" <macklinbob at msn.com>
To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>; 
<jfor at quikus.com>; "Christopher Bowne" <aj1g at sbcglobal.net>
Cc: <arc5 at mailman.qth.net>; "Clare Owens" 
<clare.owens at gmail.com>
Sent: Sunday, February 17, 2013 9:48 AM
Subject: Re: [ARC5] WW II Aircraft factory pictures


> My memory of Kodachrome says that Kodachrome was only 
> processed by Kodak labs?
>
> I have been using Exctachrome for slides for may years. 
> Still have 6 rolls in the fridge.
>
> Bob Macklin
> K5MYJ
> Seattle, Wa.

     Kodak originally processed Kodachrome only at the 
factory at Rochester, N.Y. After about a year a simpler 
method of processing was devised and Kodak established 
processing stations in other cities.  I think eventually 
there were about four.  Sometime in the 1960s (by memory) 
Kodak was sued for restraint of trade because they included 
the cost of processing in the price of the film. They had to 
stop this practice but at about the same time begain to 
license independant laboratories to process Kodachrome. 
Kodak supplied the machinery and chemistry since, even with 
simplification of the original proces, it was still complex 
and difficult to control.  Kodak had a vested interest in 
maintaining the quality of the results so was pretty careful 
about the independant processors.  Kodak also continued to 
process the film in their own labs.
     Kodachrome is a three layer film but the "couplers" or 
dye intermediate chemicals are not included in the layers. 
This was because Kodak could not find a way of 
"sequestering"  them to keep them from wandering into the 
wrong layer.  So, the couplers were put into the reversal 
developers.  The film was developed to black and white 
silver images in all three layers then re-developed in three 
separate reversal baths to generate the color, the silver 
being removed after processing.  It was the method of 
insuring the right color would appear in the right layer 
which was changed from the early to the later processing 
method.  The original method, which  I beleive was used only 
for about a year, required the controlled penetration of a 
bleach into the developed film.  After the initial B&W 
processing the film was developed again in a bath with the 
coupler for the bottom layer, this produced color dyes in 
all three layers. It was then floated on a bleach bath which 
bleached the color out of the top two layers then developed 
again in a bath with the coupler for the center layer. Then 
the top layer was bleached out and developed with the proper 
coupler for the color there. In between these steps the film 
was washed and _dried_. The drying was done to control the 
rate of up take of the bleach bath.  After about a year 
another method was devised; this one used differential 
re-exposure and made use of the remaining color sensitiivty 
of the layers.  It still took three re-development baths but 
the bleach steps were eliminated.  After this method as 
adopted Kodachrome became available in many formats other 
than 16 mm film.  Up to about 1948, when Ektachrome was 
announced, Kodachrome was made in sheet sized up to 16x20 
inches!  All the larger films were processed in Rochester. 
Commercial and advertising photographers who had come to 
rely on Kodacrhome were very upset at its discontinuance in 
sheet sizes because Ektachrome was thoroughly inferior. 
Ektachrome had the advantage that any commercial lab could 
ste up to process it although it was still quite fussy.
     Kodak had discovered a method of sequestering the 
couplers in the early 1940s which was used first for 
Kodacolor and its print paper. The color was inferior to 
Kodachrome but the processing was much easier.  At about the 
same time as Kodachrome was announced AGFA had come up with 
a multiple layer color film but using incorporated couplers. 
They had come up with a different method of sequestering the 
couplers than Kodak used.  Agfacolor was not sold outside of 
Germany and most seems to have been used by the government.
     Both methods of sequestering the couplers continued to 
be used for decades, I am not sure which method survives.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com