[Hallicrafters] S-120 receiver - celloluse nitrate lacquer?

[rbethman]

Richard,

Thank you for setting my OLD memory straight!

It has been about 5 decades since I worked in a darkroom and was 
involved with all of this.

It is just like R/C engine fuel.  Nitro Methane is added up to say 30% 
for that boost in power.

Bob - N0DGN

On 3/25/2013 11:49 AM, Richard Knoppow wrote:
>
>    This is OT but the support used for most 35mm motion picture film 
> unti 1951 was cellulose nitrate. Safety film, or cellulose acetate was 
> used for 16mm film and no 16mm film was ever made on nitrate. However, 
> the motion picture industry was reluctant to change to acetate because 
> nitrate was supposedly less turbid plus the printing equipment was all 
> designed to compensate for the shrinkage of nitrate. There were some 
> very serious film fires due to nitrate. Nitrate supplies its own 
> oxygen when burning so nitrate film fires are extremely difficult to 
> extinguish.  Motion picture theaters were required to take extreme 
> precautions to prevent film fires and to isolate them to the 
> projection room if they occured.  Nitrate film base is inherently 
> unstable but the degree of instability depends on the exact method by 
> which its made.  It turns out that historically Kodak made the most 
> stable base and Dupont the least stable. In 1951 the industry changed 
> over completely to cellulose acetate.  However, acetate has a set of 
> vices all its own. There have been at least three kinds of acetate 
> material used as film base and it turns out that one of them 
> "triacetate" was very unstable so much motion picture material made on 
> it has been damaged.  See "vinegar syndrome" for more.
>     The effects of the instability have to do with many factors and do 
> not seem to have affected nitrocellulose paints.
>     Also:  Silver nitrate is a component used in making photographic 
> emulsions but there is little or no nitrate in the finished emulsion 
> since it is converted to other silver compounds.  The developed film, 
> provided its been washed properly, has only metallic silver embedded 
> in a gelatin coating.  Color film has no silver, its bleached out in 
> one of the last processing steps, leaving only dye embedded in the 
> gelatin.
>     Animal gelatin is still used as the basis for photographic 
> emulsions since in 120 years nothing better has been found.  Some 
> plastics are added in modern film but most of what is there is animal 
> gelatin.
>
>
> -- 
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>