[GreenKeys] Fwd: Teletype wiring vinyl tubing

[Roy Morgan]

> On Feb 20, 2019, at 3:07 PM, Richard Knoppow <1oldlens1 at ix.netcom.com> wrote:
> … traditional windex is mostly diluted ammonium hydroxide with alcohol, the "streak free" glass cleaners have butyl alcohol in them. Both will attack some plastics but generally old type Windex is safer. Do not use either on cellulose acetate or nitrate (celluoid). 

A note that may prevent a disaster:

Cellulose nitrate is/was known as guncotton and is extremely flammable, used in guns and cannons years ago.  It was the main base material for most photographic films until the late 1940’s. 

Kodak completed conversion to acetate film bases in 1952.  Wikipedia notes: "Acetate has always been used with 8 mm and 16 mm formats, as they were originally created for amateur home movie usage, and generally was used for most sub-35 mm formats to minimize risk to the general public.”

https://en.wikipedia.org/wiki/Film_base

There are two practical ways to tell if grandpa’s films are nitrate or acetate:

- drop a tiny bit into a small jar of trichlorethlylene and see if it sinks or floats. (Nitrate sinks, acetate floats, and polyester will remain around the middle.) 

	• Float testing of the specific gravity of the base in trichloroethylene should cause nitrate to sink, acetate to float, and polyester to remain around the middle. However, this can be complicated by impurities and deterioration factors.

- look for the words “Safety Film” on the edges of the negatives, though Wikipedia claims that nitrate films may say “safety”.

Also, if your family films date from before 1948 or so, assume they are nitrate.

An impractical way to tell is to ignite a SMALL bit of the film and see if it melts or if it burns furiously.  There is no way to extinguish a nitrate film fire as it has it’s own oxygen.  

Roy

Roy Morgan
K1LKY since 1958
k1lky68 at gmail.com