[GreenKeys] Old Photo Model 15

[Roy Morgan]

On Jun 2, 2009, at 10:40 AM, bonamod at bellsouth.net wrote:

> Not sure if anyone looks at old photo's but found this on a website  
> today
> http://www.shorpy.com/node/6229?size=_original

I might comment on the caption, which says, "Medium-format safety  
negative by Jack Delano. "   What's the "safety" part of that, you  
might wonder.  At that time cellulose nitrate based film had been used  
in the past,  and was and is quite dangerous.  The "Safety" film  
mentioned was developed to avoid this danger had supplanted most film  
base by the time the photo was taken.

Cellulose nitrate film stock (the flexible base) is the same stuff  
that gun cotton is made of.  If ignited, it burns furiously with no  
need for outside oxygen, and can explode violently under some  
circumstances.  If it has been stored properly, it is still useful to  
support the emulsion of the negative, but if you have any, do be  
careful with it.  If it has been processed badly, and/or stored  
incorrectly, it can melt into a gooey mess that is a film archivists  
nightmare.

There is an easy way to tell what you have - you immerse even a tiny  
chip of the film in a particular solvent: if it floats, it's one  
material, if it sinks, it's the other one.  I won't depend on memory  
for the missing details now, but  you can find them out on the Kodak  
web site.  If I remember correctly, mosy any amateur photo negatives  
made before about the mid 1920's is nitrate based, and any after the  
early or mid 1930's will be "safety film" (and will be marked as such  
on the edges).

Keep all of grandpa's negatives away from flames!

Roy

Roy Morgan
k1lky at earthlink.net
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Groton NY, 13073
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