We all know that the silver used in photographic emulsions is recoverable -- but most of us aren't sure how to do it or whether it's practical for us to do so. Del Borer, coordinator of press photography for Eastman Kodak, recently shed some light on how to recover silver and how much can usually be recovered.

In an article in Kodak Data-Lines, a report for news photographers, he goes into the details of silver mining in the darkroom.

He states that with today's silver prices it is practical for the avid amateur with a darkroom to look into a silver-recovery program. Kodak now manufactures a chemical recovery cartridge, a recirculating unit, and a kit for adapting a chemical storage tank as well. The installation compares very favorably in price with the more expensive electrolic recovery cells used by commercial labs. They can cost from $150 to $15,000.

But even with this less expensive system you have to be a heavy user of photographic materials. For example: a fixer used in processing 1,000 8 x 10 black-and-white prints contains about two troy ounces of silver, which at the current price of $15 per ounce would be worth $30. A pound of scrap film may contain about $2 worth of silver and a pound of old black-and-white prints another $1.

These figures may help you figure out if your photo production is high enough to justify the cost of silver recovery. Additionally, you must understand that what you do recover by this process is a silver sludge that has to be refined and resold at market demand, which doesn't mean top prices. Your sludge with the silver lining may range from 30 to 90 percent pure silver, and the refiner's cut can halve the going price.

If you are interested in pursuing your lost silver, send for the following publications from Kodak: Silver Recovery with the Kodak Chemical Recovery Cartridge, Type P (J-0); Recovering Silver from Photographic Materials (J-10); Potential Silver Yield from Kodak Photographic Products (J-10B). Write to: Department 454, Eastman Kodak Company, 343 State Street, Rochester, New York 14650. Q: Could you tell me how I can make titles for my home movies? I'm especially interested in titles with moving backgrounds and a fade-in and fade-out technique like I see in commercial movies.

Do you also have a suggested book that would teach me movie technique? Superimposed white titles can be made through double exposure. The white lettering can be set on a black velvet background and exposed, then the camera taken out into the field, the film rewound and the scene reexposed on the same film. Some movie cameras have this rewind feature.

Titles can also be superimposed in a lab by means of double-exposing an original film and a high-contrast negative title in a motion picture film printer by using the A and B roll printing techniques. (You can check with your processing lab for this service.)

Fade in and fade-out effects can be accomplished with a fade-in button or a variable shutter setting to achieve the fade. Most modern movie cameras have this feature; for those that don't use the following technique.

First, take a meter reading of the scene; this will tell you which f/stop setting to use for the correct exposure. Then, to start your fade from dark to light, shoot a short burst with the lens cap over the lens. To continue the transition, switch the setting to manual and set the aperture at f/22. Shoot three frames at this small opening and then continue to open up the lens at each half-stop and run three more frams at each setting until you have reached the correct exposure. (Your sequence would run like this: black, with the lens cap on and then a gradual lightening up to the right exposure.)

To fade from light to dark, reverse the procedure, starting at the correct exposure and then closing down the lens and finally finishing with the lens over the lens.

I recommend The Movie Maker's Handbook, edited by Christopher Wordsworth, as an excellent aid to both home and professional movie-making. The publisher is Ziff-Davis and the distributor is McGraw Hill. The price of $25 may sound steep, but once you see the book, you'll be convinced that it's worth it.

Another recommendation is the Encyclopedia of Practical Photography, edited and published for the Eastman Kodak Company by AMPHOTO, American Photographic Book Publishing Company, which is available in 14 volumes and has much more than movie-making -- it's a complete course in all branches of photography.