----- Original Message ----- From: "Carlos Manuel Freaza" <cmfreaza@xxxxxxxxxxxx> To: <rollei_list@xxxxxxxxxxxxx> Sent: Monday, May 30, 2005 4:43 PM Subject: [rollei_list] Re: looks like ... agfa Sala > Thank you very much for the detailed explanation, > Richard, it was necessary for me, in general we > associate "film base" with the film back (acetate > etc.) in Spanish. > I am only using color films for 35 mm, however if > nobody answers the question, I'll ask to a friend of > mine tomorrow.- > > All the best > Carlos Carlos, that is correct. The support or base is the material on which the light sensitive emulsion is coated. Many materials have been used historically, mostly either Cellulose Nitrate or some form of Cellulose Acetate. Many films are now coated on some form of polyester (Kodak Estar, DuPont Cronar, etc.). Polyester has the advantage of excellent dimensional stability, very high tear strength, and very low absorption of moisture during processing. However, it isn't perfect so Cellulose acetate continues to be used for many films. Cellulose Nitrate was the first flexible film base, introduced in the late 1880's. It has good mechanical properties and optical properties, but is very highly inflammable and is chemically unstable. Nitrate film was discontinued all together in 1951, at least in the U.S. No 16mm film was ever made on Nitrate, and Kodak discontinued it for still films in the early 1930's although Agfa and others continued to make it. Nitrate film evolves oxygen when it is ignited so its nearly impossible to extinguish. Nitrate film will burn under water and under sand! --- Richard Knoppow Los Angeles, CA, USA dickburk@xxxxxxxxxxxxx --- Rollei List - Post to rollei_list@xxxxxxxxxxxxx - Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe' in the subject field OR by logging into www.freelists.org - Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with 'unsubscribe' in the subject field OR by logging into www.freelists.org - Online, searchable archives are available at //www.freelists.org/archives/rollei_list