International projectionist (Jan-Dec 1954)

should be cleaned the same way — with utmost care. 1. Dust. Remove with a soft, dustfree camel's-hair brush of the type used by water-color artists. 2. Surface Slightly Soiled. Breathe on the surface and gently wipe with a very soft, dry linen rag (frequently washed). Breathe on the lens again before each wiping. 3. Surface Heavily Soiled. Dissolve a piece of Ivory Soap the size of a small pea in a pint of pure (preferably distilled) water to make a weak soap solution. Dampen a clean linen rag with this mild solution, wipe the surface, then polish with a dry linen rag as under (2) above, breathing on the glass. 4. Oil on the Surface. Moisten a soft linen rag with clean gasoline (lighter fluid) and wipe off oil. Continue as under (3) and (2) above. 5. Special Stains. Paint. Remove cautiously with turpentine, and continue as under (3) and (2) above. Film Cement. Remove very cautiously with a half-and-half mixture of acetone and chloroform, and continue as under (3) and (2) above. Apply s PUCES ^^ NOT y HOLDING Film breaks are costly. Play safe by using JEFRONA All-purpose CEMENT Has greater adhesive qualities. Don't take our word for it. Send for FREE sample and judge for yourself. CAMERA EQUIPMENT CO. 1600 Broadway New York 19, N. Y. these powerful solvents very sparingly, and only to the soiled spot, not to the entire lens-surface. Warning! Use only linen or cotton rags for cleaning lenses, never wool, silk, or rayon, which scratch. Wool also leaves greasy streaks on glass. Do not use "lens-paper" on coated lenses, and especially avoid siliconeimpregnated spectacle-cleaning papers. Use only a soap solution containing nothing but a pure soap, such as Ivory cut from a fresh bar. Never use soap powders or soapless detergents, many of which are adulterated with caustic chemicals capable of attacking glass or dissolving the magnesium fluoride coating. Warning About Solvents Never wash lenses with alcohol, acetone, ether, carbon tetrachloride, or similar organic solvents which may seep into a lens and blister the cements with which achromatic couplets are cemented together. Avoid all commercial lens-cleaning nostrums. No attempt should ever be made to take modern sealed lenses apart. The oftener we clean the mechanisms of our projectors the better they will work ; but lenses should not be cleaned more often than is absolutely necessary. A lens can "wear out" only through over-cleaning. Examine the lens daily and clean only the surface which needs cleaning. In nearly all cases the rear lens facing the aperture gets the dirtiest; the front lens usually having nothing more than a few dust-specks which can be whisked off with a brush. The rear surface is exposed to hot, oily film, and thus gradually becomes fogged by an almost invisible coating of oil-droplets. This oil-film makes Wcuiied: Experienced Sound Engineers for Theatre Servicing. For particulars write to INTERNATIONAL PROJECTIONIST Box 954 19 West 44 St., New York 36, N. Y. the picture dull and hazy; but it is readily removed with the weak soap solution. Barring accidents, a lens will last almost indefinitely with sensible treatment. One important thing to guard against is the projection of blank light to the screen without having the projector running. Even though the rotating shutter cuts the light in half, it is unwise to leave the light on the lens too long. The intense heat may blister the Canada balsam or synthetic resin used for cementing the lens-elements together. When high arc-amperages are used, the sudden heat of the full beam on a cold lens may actually crack the rear element. This is especially likely to happen if the lens is covered with a dew of moisture condensed from the air. [CONCLUSION] HEADQUARTERS FOR FILM MAGAZINES Give your Projectionist, Wenze! 25" Magazines. He can use that "Extra Changeover Time" for other Booth requirements. • The Wenzel 25" Magazine is not a "made over" 18" magazine. It has been designed and engineered especially for the job it is required to do. The Wenzel 25" Magazine, known as PRO-51 Upper, and PRO-52 Lower, is S-Vs" deep, and when the beaded type door is closed, there is approximately 4" inside clear depth in the magazine. Wenzel also has a Hand Rewind for 23" Reels, that is complete in itself, and can be used with a motor, if desired. FILM MAGAZINES 18" Standard Type 1 8" De Luxe Type 25" All Purpose Type Write for complete illustrated and descriptive literature, or ask your supply dealer. WENZEL PROJECTOR COMPANY 2505 2519 S. State Street Chicago 16, Illinois . Cable Address: WENZKO INTERNATIONAL PROJECTIONIST • APRIL 1954 33