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288 TALBOT September
The best of these carbon tetrachloride-wax mixtures at their most suitable concentrations are given in Table I. It is a well-established fact that ethyl cellulose will raise the melting point and impart hardness and toughness to wax mixtures and that the mixture will have properties different from those of the individual components.3' 4 It is for this reason that ethyl cellulose has been incorporated into some of the formulas.
TABLE I CARBON TETRACHLORIDE-WAX SOLUTIONS FOR 16-MM FILM
Max. Useful Per Cent
Cone, in Film Friction,
Wax CC14 Ounces
Carnauba*
0.03
4.3
Pentawax 217 1
0.125
4.0
Johnson's WM 169CJ
0.125
3.9
Beeswax (0.025%)-Ethyl Cellulose (0.075%)§
0.10
4.5
* No. 2 North Country Carnauba Wax obtained from Sprahl and Pitsch, 141 Front Street, New York City.
f Obtained from the Heyden Chemical Company, 393 Seventh Avenue, New York City.
J Obtained from S. C. Johnson and Son, Inc., Racine, Wisconsin.
§ Type T-200 Ethyl Cellulose obtained from Hercules Powder Company, Inc., Wilmington, Delaware.
B. The Evaluation of Lubricants
A good over-all application of wax to 16-mm film will leave an invisible coating on the film, will not pick up dust, nor show fingerprints, and will provide good steady projection even after the film has been subjected to conditions of high relative humidity. Inasmuch as many projectors will not project freshly processed, unlubricated films of high moisture content without damage to the film, either in respect to the scuffing off of emulsion particles, or damage to the perforations, or both, these observations may serve as a means of evaluation of film lubricants. Freshly processed rolls of 16-mm film are treated with the lubricant to be tested, and these rolls, along with rolls of untreated film, are festooned in an atmosphere of high humidity, such as 70 per cent relative humidity at 70 degrees Fahrenheit for two hours. At the end of this time, the rolls are reeled and tested for