Extracted from Photoforum:

Date sent:        Tue, 05 Mar 1996 20:37:28 +1100 (EDT)
From:             Jesse David Andrewartha [s9406213@minyos.its.rmit.EDU.au]
Subject:          8"x10" colour IR
To:               photoforum@osfmail.isc.rit.edu
Send reply to:    photoforum@listserver.isc.rit.edu

I need some help!

I recently acquired for the purpose of my imaging portfolio 100' of Kodak Aerochrome 2443 colour infrared film (format: 9.5" x 200"). My intention is to cut the film into 8"x10" sheets and apply the film to pictorial imaging. This has succeeded, but to a point.

My original plan when it came to the processing was to cross process the film using low temperature altered C-41 chemistry. When developed in normal EA-5 chemistry, the backing is eliminated to leave a clear rebate. However, the film emerged from the altered C-41 process with a heavy magenta layer beneath the emulsion. I know this is not fog, as it covers the film evenly and does not alter colour when wet, whereas the emulsion is blue when wet. This has got me stumped. I can print through the cast in enlarging, however, this results in an unwanted neutral density and is a problem I would like to solve rather than put up with.

Does anyone have any ideas on what I could do or which direction I can take to aim towards so I may eliminate this magenta backing. I have begun to play around with various chemistries, but any lead would be much appreciated.

The following is the C-41 process I used, which works well with 35mm and 70mm colour infrared, but does not work with Aerochrome 9.5", as detailed above

C-41 developer		12 min
wash			 4 min
E-6 bleach		 6 min
wash			 4 min
E-6 fix			 6 min
wash  			 4 min
Hardener*		 2 min
wash			 8 min
Photoflo		 1 min

If anyone has any suggestions whatsoever, please mention them- I would be incredibly grateful.

Thanks heaps,

Jesse

From: "Kevin Johnson APL Inc." 
To: 
Subject: How to develop Ektachrome IR / Aerochrome IR yourself in C41 chemistry
Date: Wed, 31 Dec 2003 10:54:42 -0500

If you are still in need of help with this please let me know. It sounds like your high magenta fog is from over processing. The film you have I am fairly sure is prior to the for hardened film and requires a prehardner and a neutralizer before developing. The 1996 is the time that the changes were made so you may be OK.

Kevin

Michael Kevin Johnson, Vice President
Aerial Photo Lab, Inc.
When Superior Imagery Counts!
200 Fentress Blvd. Suite D, Daytona Beach, FL 32114
386-253-5041 Fax: 386-253-5031
MKJ@AerialPhotoLab.com
www.AerialPhotoLab.com

From: "Kevin Johnson APL Inc." 
To: 
Subject: RE: How to develop Ektachrome IR / Aerochrome IR yourself in C41 chemistry
Date: Wed, 31 Dec 2003 12:39:57 -0500

IR film processed to a negative:

The infrared films can be processed to a negative and some companies have been doing it for a large number of years. I personally began using the altered process in 1983. There is some difference in the films used now, in approximately the mid 90's Kodak made some major changes to the films in order to remove two chemicals in the processing of the film for environmental reasons (THANK YOU KODAK). The process used to have a prehardner (formaldehyde based) and a neutralizer. If these chemicals were "skipped" the emulsion would fall off of the film. When the new film came out which is also known as "forhardened films" and the prehardener and neutralizer are no longer used. Here is what I would recommend as a "starting Point" for your infrared film processed to a negative based on machine processing of the film.

IR to a Negative requires 3:15 development time at only 92 degrees
Normal c-41 requires 3:15 development time at 100 degrees
Aerial c-41 requires 4:20 development time at 100 degrees
Push c-41 aerial requires 5:20 development at 100 degrees

IR to a negative is approximately 1-f stop less development then normal c-41, BUT, you do not want to altered the exposure used by 1 f-stop. If you process your film at the normal c-41 mode or aerial c-41 you will have a very high magenta cast to your base density and it will also effect the ability of the film. All of the rest of the process is the same with one addition. You MUST use a formaldehyde based stabilizer at the end such as Kodak Stabilizer 3 such as Kodak #873 5599. Some of the very old IR films would tend to have more of an infra-orange look to them with this process. It all depended on the infrared sensitivity which used to very dramatically. I have not seen that variance with the new films.

Hope this helps,
Michael Kevin Johnson, Vice President
Aerial Photo Lab, Inc.=20
When Superior Imagery Counts!
200 Fentress Blvd. Suite D, Daytona Beach, FL 32114
386-253-5041 Fax: 386-253-5031
MKJ@AerialPhotoLab.com
www.AerialPhotoLab.com

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