What follows has been sitting in "work-in-process" files for years. It was supposed to become a 20-page booklet with detailed procedures, photos of equipment and results, etc. I am so busy with other projects that I probably will never finish this, so I'm offering it for free as a sample of the kind of weird stuff my research turns up.

Introduction

The process described in this manual was developed by the author for his own use. It owes very little to the literature. By carefully following the instructions herein, the reader will be able to reduce a page of text or line drawings to a rectangle of 1.0 by 1.2 millimeters, a reduction of about 210:1! Two methods are provided: one for the well-equipped and experienced amateur photographer, the other for the unskilled owner of a camera and little else. The first is presented in outline form only, since the reader is assumed to already have a thorough knowledge of standard photographic technique. The second, of course, assumes nothing. Note that some materials and hardware commonly available are mentioned only in the text, not in the bill of materials. The reader with absolutely no tools or materials at his disposal will have to make up his own shopping list in addition to that given. Note also that no mention is made of applications; the reader is assumed to have had one in mind when he bought this booklet. And finally this process, like any other, is amenable to improvement. Any reader who discovers a way to improve on the methods expounded below is welcome to write to the publisher whose address appears above.

Materials and Equipment:

• Camera, 35mm, (single-lens-reflex type preferably) with B (Bulb) setting on shutter-speed selector and cable release
• Enlarger, 35mm, condenser type (substitute explained in text)
• Cellophane, clear
• Ammonium bichromate (called also Ammonium dichromate)
• Film, 35mm, B&W, high-contrast
• Developing chemicals for above
• Lab gloves, cotton (lint-free)
• Distilled water
• Lighter fluid

Explanation of the Process:

In our process the support is cellophane, a clear plastic foil consisting of pure cellulose, the basic material of plant fibers such as cotton, which has been regenerated (dissolved and re-solidified) to change it from fibers to sheets. Unlike most sheet plastics, cellophane is porous and absorbent; when treated with a bichromate solution, it will adsorb the bichromate onto its surface. Where light hits the treated cellophane, the released chromium oxide combines directly with the cellulose to form a brittle purplish compound. This change in color from clear to purple is what gives us our visible image. To fix the image, the uncombined bichromate is washed away with clear water. The process is negative-working, meaning that if the treated cellophane is exposed to light through a negative, the result is a positive image, and conversely. In most Graphic Arts processes, the negative is contact printed onto the bichromated surface. In our case, a 35mm (24x 36 mm) negative is projected onto the cellophane, forming an image reduced 21:1. The negative is made by photographing a page with a 35mm camera loaded with high-contrast film, for a reduction of about 10:1. Thus the total reduction of 210:1 is achieved in two steps. The reader may wonder what justifies the inconvenience of exposing and developing the intermediate negative. There are two reasons: first, a 210:1 reduction demands a higher resolution than that of any optical system the reader is likely to have and secondly, the bichromated cellophane requires so much light that it can only be conveniently exposed under a transparent negative. The extra step is the price we pay for the use of available and affordable equipment.

Procedure:

1. Preparation of text or drawings: text and drawings should be in black ink on letter size white paper. All mistakes should be opaqued with white correction fluid. A good test for the clarity of your copy is to copy it on one of the less sophisticated office-type copying machines. If you get good, crisp copy with one of them, you've done well.
2. Preparation of 35mm negative: this paper is not the right place for a dissertation on the photographic process. The author assumes on the reader's part a basic knowledge of photography which can be easily acquired if it is lacking. If your enlarger can be used as a copystand, load your camera with Kodak High Contrast Copy film or its equivalent (see Appendix), mount it on the camera-bracket and adjust the bracket so that the copy fills the camera's field. Then focus the camera carefully. The copy should be illuminated by two 75 W lamps with reflectors set on either side of the copy and shining upon it at a 45 degree angle. Ideally, exposure readings should be taken with an incident-light meter set on the copy, but if one is not available simply place your hand, palm up, on top of the copy and take your reflected-light reading off your palm. For best results, your lens should be set two f-stops below its maximum aperture and correct exposure obtained by adjusting the shutter speed. If no enlarger is available or yours cannot be used as a copystand, then tape the copy to a wall with the long edge horizontal; then set your camera on a pile of books until its lens is at the same height as the center of the copy. Regardless of which method you use, take care that the film plane of the camera is parallel to that of the copy. Use a cable release to trigger the shutter without jiggling the camera. Develop your film in a high contrast, fine grain developer (see Appendix). Fix and wash using standard B&W technique.
3. Preparation of the Cellophane: Commercial cellophane, such as is used for wrapping packages, is coated with a plastic resin to make it non-porous. Uncoated cellophane is available from chemical supply houses, which sell it as dialysis tubing or dialysis membrane. In all that follows we will assume that you have only coated cellophane available. The coating must be removed from one surface of the cellophane. Using a wad of cotton moistened with lighter fluid, rub the surface of the cellophane briskly. Turn the cotton over, remoisten and repeat. Hold the cellophane up to the light. The area you have rubbed should appear duller than the rest. Repeat the process using a fresh piece of cotton to make sure. From now on, handle the cellophane with tweezers or wear lint-free lab gloves. Cut out a piece of stripped cellophane 35 x 40 mm. Notch the lower left corner, clean face up. Dissolve the orange ammonium bichromate crystals in a small quantity of distilled water until added crystals no longer dissolve. The next step is to be carried out in total darkness. Immerse the prepared piece of cellophane in the saturated ammonium bichromate solution. Agitate it to remove air bubbles clinging to its surface. After twenty minutes, remove the sensitized cellophane and blot it between paper towels to dry it. Sensitized cellophane must be used immediately.
4. Exposure: Place your camera lens-down on a level surface and open the back. Position the dry, sensitized cellophane over the exposure opening in the camera, stripped face down. The notch will be on the lower right or top left corner. Keeping the camera level, close the back. Now you may turn the lights on. Remove the lens from your enlarger and turn on the lamp. Set the enlarger so that the negative carrier is one meter above the baseboard. If the condensers are adjustable (some enlargers allow the lamp to be raised or lowered instead), set them so that an image of the enlarging lamp's filament appears on the baseboard. Place the camera, lens up, on the baseboard with the lens centered over the filament image. Place the negative in its carrier, and the carrier in the enlarger. Fit the camera with a cable release equipped with a set-screw. Set the shutter-speed selector on <169>B<170> and the aperture two f-stops below maximum opening. Set the focusing ring to one meter or three feet. Turn on the enlarger, press the cable release to open the camera's shutter and set the screw to hold the shutter-release in. Expose for twelve minutes as a test. Release the set-screw and allow the shutter to close. Turn off the enlarger. In subdued light, remove the cellophane from the camera. The whole piece should have an orange tint. There will be a small purple rectangle in the center of the piece.


A picture of the improvised setup, for making do without an enlarger, is shown below. 
In this arrangement, the condenser is a simple plano-convex lens large enough to cover the negative and resting directly on it, and the filament image is focussed on the floor by adjusting the bulb-to-carrier distance. Also shown is a picture of the negative carrier/mask for the improvised setup.


5. Fixing: If the cellophane is allowed to remain impregnated with the bichromate, continued exposure to light will cause the whole piece to darken. In fact, even without exposure to light the whole piece will darken, given sufficient time. To prevent this, the cellophane must be immersed in warm running water until the orange cast vanishes. Clip a clothespin to one corner to prevent it from vanishing down the drain.
6. Corrections: If your text is sharp, but faint, increase exposure. Do the same if there is no visible image. A purplish haze in the image area means that the contrast of the negative is not sufficient, or you have over-exposed, or both. By shifting the piece of cellophane in the camera, the same piece can be exposed several times in different places.

Improvement Needed