This is topic Green scratches on red film??? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Greg Mueller (Member # 17) on 10-20-2003, 10:03 AM:
 
I have an old print from the 50s that has turned red. When I first got Film Guard I tried it on that film as a test. The film was quite dirty and had what I thought was black scratches. As the Film Guard worked I began to see that the scratches where not black but green. Apparently the green scratches had filled with dirt and the Film Guard cleaned the dirt out showing the true green color.
So if the aging of the Eastman film makes it lose it's blues and greens leaving only the red, how is it there is still green in the scratches?.....John?
 

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Posted by Sam Hunter (Member # 1119) on 10-20-2003, 10:08 AM:
 
Corrosion

Thats a good question though.
 

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Posted by John Pytlak (Member # 331) on 10-20-2003, 10:20 AM:
 
Evidently, the "dirt" filling the scratches in that old film was oil and miscellaneous debris. When dyes fade due to improper storage, you usually lose only a percentage of the dye's density; most of the dye remains.

Here are some excellent papers on the chemistry of dye fading:

http://aic.stanford.edu/jaic/articles/jaic31-02-005.html

http://unesdoc.unesco.org/images/0005/000586/058641e.pdf

http://www.rit.edu/~661www1/sub_pages/8contents.htm
 

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Posted by Dominic Case (Member # 1830) on 10-20-2003, 06:39 PM:
 
The film image consists of yellow, magenta and cyan dyes not red, green and blue. Magenta is the top layer in print film, then cyan, with yellow at the bottom.

When film gets scratched and the top layer is removed, you are left with green (yellow + cyan, missing the magenta). Even if just the protective supercoat is removed, and oil gets into the emulsion, it will rapidly cause that magenta layer to fade. So you get green scratches again. As John suggests, dirt filling the scratches made them appear black before cleaning.

Now, the rest of the image appears red because the cyan dye layer has faded most of all (due to time, temperature, humidity, etc) over the years. From the era of that print, cyan was the least stable dye. But there's probably still a proportion of cyan there - enough to make the scratches appear green by contrast with the rest of the image.
 

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Posted by William Hooper (Member # 71) on 10-21-2003, 12:06 AM:
 
I ran a cartoon that had turned green - all over, the color change was in the base. Onscreen, white areas in the picture were green, etc. Pink is better.
 

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Posted by John Pytlak (Member # 331) on 10-21-2003, 05:46 AM:
 

quote:

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I ran a cartoon that had turned green - all over, the color change was in the base. Onscreen, white areas in the picture were green, etc. Pink is better.

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