A Non-Silver Manual: Enlarged negatives

The chapter called “Enlarged negatives” of Sarah Van Keuren’s book “A Non-Silver Manual: Cyanotype, Vandyke Brown, Palladium & Gum Bichromate with instructions for making light-resists including pinhole photography”.

Writer / Sarah van Keuren

Read the previous section of this book.

Those who photograph with large-format cameras (4 x 5 inches and up) can contact-print directly from their view camera negatives in non-silver. I recommend normal exposure but prolonged development of such negatives to boost highlight density if they are to be printed from in low-contrast vandyke or platinum/palladium. It is possible to make handsome contact prints from medium-format negatives also, as John Joyce has done with 21/4 inch negatives in palladium. But if you want bigger prints from 35mm negatives, or prints that are larger than what you’d get from contact-printing medium or large-format negatives, you will have to make enlarged negatives.

There are many ways to make enlarged negatives: in a chemical darkroom, on a computer and desktop printer, or at a service bureau. A variety of films and papers can be used in both the analog and digital realms. Each procedure and material gives a different rendition of the original negative.

Within the analog realm of the chemical darkroom, choices range from a high-contrast graphic arts interpretation with lith film, to the continuous tone of the few large format films that remain in production, to the fibrous softness of a paper negative. Lith film will be familiar to printmakers who have used it to produce offset lithography plates, photo-etchings, or photo-silkscreens. Negatives rendered on enlarging paper might be familiar to photographers who have used pinhole cameras. Commercial, Copy and Duplicating films may be less familiar and, since they have been widely discontinued, they may remain unfamiliar. In this revision I have omitted discussion of them.


Arista-II Ortho Lith film is currently the most widely available film of this sort (see Freestyle in “Resources“). The unifying feature of all lith films is their graphic, high-contrast response when used with the recommended developers. The term ‘lith’ encompasses panchromatic lith film that is sensitive to all colors (used to make color separations) and orthochromatic lith film that is sensitive to blue and green and can be used with a red (1A) safelight.

As is the case with most silver-gelatin films and papers as well as with most non-silver processes, lith film is negative-acting. Therefore, when you project a small format negative onto a sheet of lith film, a positive transparency will result just as would have happened if you had put enlarging paper in the easel instead of lith film. This positive image on film is called the interpositive. If you were exposing a photo-silkscreen, photo-etching, or positive litho plate, you could stop your silver darkroom work after producing the positive, but with negative-acting non-silver processes, it is then necessary to make a negative from this interpositive.

The enlarged negative is obtained by projecting or contact-printing the interpositive onto a second sheet of film. For instance, you could enlarge from a 35mm negative onto a 4˝ x 5˝ interpositive which could then be projected in a 4˝ x 5˝ enlarger onto a piece of 11˝ x 14˝ film. To really save film, you could contact-print an entire sheet of 35mm negatives onto lith film as if you were making a traditional contact sheet on enlarging paper; you could then cut the positives into strips and project from single frames like 35mm negatives onto sheets of lith film. This would create a very broad effect with huge grain on your enlarged negative. Any speck of dust on the 35mm negative or positive would be greatly magnified on the enlarged negative. It is possible to spot such open areas with Pitt Pens or something else that blocks actinic light. It is also possible to scrape away silver where it is not wanted with a scalpel or abrade it with sandpaper or steel wool. But an enlarged negative with the finest detail and tonal nuance is made from a full-size positive that is contact-printed to get the enlarged negative. And with lith film, a flat, tonal interpositive can yield a more detailed enlarged negative.

Ortholith film comes pre-cut in many sizes. Unlike most sheet films, it is not code notched. The emulsion side is dull and pinkish; the base side is glossy and red with anti-halation dye which prevents light from passing through the film and reflecting slots and scratches on your easel onto your film from the back. All lith film (orthochromatic and panchromatic) must be handled with more care than photographic paper or other films since fingerprints show up very easily. Plan to make enlarged positives and negatives with half-inch margins and touch only the edges of the film. During tray processing, do not use tongs, which usually scratch or contaminate the film. Instead wear sheer disposable gloves on both hands, hold the film by the edges, and drain the developer off of it by tilting the film back and forth from one corner to another to avoid streaking. Areas that were solid mid-tones in the original negative are especially prone to streaking.

To obtain a contrasty positive (on the way to getting an even more contrasty enlarged negative), develop your lith film in Kodalith developer or its equivalent. Make a careful test strip before exposing and developing an entire sheet of film. The duration of your exposure and development will determine the dividing line between opaque black and clear film base in your lith transparency. You can make a number of different enlarged negatives, via inter-positives, from the same small format negative by varying exposure and/or development times. The split between clear and opaque film will fall at different densities, like a topographical map. You can then print a different gum bichromate color, for instance, from each negative, one on top of the other. The result will be a posterized image (think Andy Warhol but less graphic with transparent gum colors).

Dot Pattern

To obtain a fine random dot rendition of a camera negative, project it through a sheet of ground or non-glare glass that is lying, rough side down, on top of lith film, and develop the film in the recommended developer. This method relies on the ground or subtly etched glass to bend light and fragment the image into very fine random dots.

Another kind of dot pattern, no longer random, can be obtained with a traditional dot screen (halftone) that is in tight contact with lith film either under an enlarger or in a copy camera. Before the digital revolution this method provided the high-contrast transparencies used in offset lithography. A halftone screen was expensive and easily scratched. It consists of tiny continuous-tone openings in a grid. Light projected through or reflected from an image penetrates the continuous-tone parts of the screen in varying amounts. Upon development, solid silver shapes of varying size within the grid form either a positive from a negative or a negative from a positive.

These ways of generating images suggest continuous tone while meeting the full-ink or no-ink requirements of offset lithography and screen-printing.

Continuous Tone on Lith Film

Unlike screen-printing and offset lithography, non-silver processes can render fine gradations of tone as varying amounts of actinic light penetrate different parts of a continuous-tone negative. As mentioned earlier, a halftone or even a random dot is not necessary unless you specifically want the look of it. Many non-silver artists work with view cameras or big pinhole cameras and contact print their large-format continuous-tone negatives directly against coated paper.

Although lith film is designed to be used with a high-contrast graphic arts developer, many non-silver workers use lith film in view cameras, pinhole cameras, copy cameras and under enlargers. They develop both positives and negatives in diluted paper developer (Dektol or any other normal paper developer) to get partially continuous-tone lith negatives. Shadows still fill in and highlights block up, but in the midtones (between about Zones III and VII) there is a continuous tone. Exactly where that range of continuous tone falls depends on exposure and development time — so again, you should make careful test strips. I must add here that ortholith film should be watched carefully under the red safelight during development. You should be ready with two gloved hands to yank it from the developer at just the right moment, and quickly slip it into the stop bath. For continuous-tone films it is much harder to judge development by inspection. With them flexibility should be in exposure time and a set development time should be adhered to. But lith film has none of the confusing chemical fogging of shadow areas that makes it hard to judge continuous-tone films during development under a red safelight.

There is no recommended dilution of paper developer to use with lith film because so much depends on the nature of the original negative, water temperature, status of developer and the desired results. Some of you will find that normal strength paper developer suffices with a minimal exposure onto the lith film. Others will dilute the paper developer with 10 times its volume in water or even more to get a satisfactory negative. Unfortunately Kodak’s Selectol-Soft developer (or the equivalent) that got maximum highlight separation and shadow detail out of lith film is no longer available.


You may have made photograms already by laying objects on paper sensitized with non-silver chemicals. The result was light shapes on a dark ground. If you would like to have dark shapes on a light ground, try placing or contacting objects on a sheet of lith film under an enlarger light or another light source. If some of the objects are semi-transparent, make test strips to find out which exposure gives the desired rendering of intermediate tones. Try different developers for a variety of interpretations. The resulting photogram negative can then be contact-printed against a non-silver process to obtain a positive photogram print. Obviously, this kind of photogram is more repeatable than an array of objects placed directly upon sensitized paper.

Contact Prints

At the beginning of the introductory course in non-silver, in an effort to bridge the gap between the hand and the camera, I ask each student to make a tonal drawing or painting on a translucent material such as tracing paper or frosted mylar. Some of the students, realizing that values will be reversed when they contact print against paper sensitized with cyanotype or vandyke, manage to draw negatives. Others work abstractly or accept the inverted values. For those who produce positive drawings or paintings that should be rendered as positives for full effect, there is the option of contact printing their work against lith film to get high fidelity negatives. This can be done under a calibrated light source such as an enlarger (without anything in the negative carrier) where careful test strips will determine exposure times. The original must be snugly contacted against the film under glass, in a contact frame of some sort, even if it is a simple arrangement of masonite, foam, and plate glass. The glass must be free of scratches and dust, which show up clearly on sensitive lith film. (This is not the case when printing in non-silver where the powerful actinic light burns through such minor obstructions.) Different developers may be used for a variety of interpretations.

Wildly Varying Exposure Times (film-base-plus-fog density)

An easy test of a film’s sensitivity to safelight is to lay a coin on a piece of film for the amount of time it might be under the safelight while being exposed and then develop it. If you see the coin shape as a clear disk on a gray background you know that your film is being fogged in the darkroom. Students tend not to recognize such fogging on their negatives when they look at them on a light table because the image is still visible and then they are mystified when their image barely prints in non-silver. A simple way of perceiving fogging is to lay the dry developed negative on a piece of printed matter in normal light. You should be able to read the text through the open parts of the negative.

Test to see if a film has been accidentally fogged by other means by transferring a piece of film straight from the film/paper safe into paper developer, process, and see if it looks fogged overall or in certain areas. Very old film fogs around the edges.

Expensive continuous-tone film has a fairly thick mylar support, the film base, that holds back some light. In addition there is a certain amount of unavoidable ‘chemical fogging’, a veil of metallic silver that is deposited on most continuous-tone films (but not on lith film). These two factors plus fogging from causes mentioned above (and others) help to explain why a single exposure time under a specific light source for all negatives onto a particular non-silver process cannot be prescribed.

If you couldn’t avoid fogging and it is reducing contrast and extending exposure time significantly, you can easily prepare a homemade version of the proprietary ‘Farmer’s Reducer’ to remove some of it. Set up two trays of water, one with a perfectly flat bottom. Sprinkle potassium ferricyanide, maybe a teaspoon per quart or liter, into the flat tray and agitate until the water is yellow and there are no red grains that haven’t dissolved. Add a few ounces of liquid fixer concentrate to the same tray. The potassium ferricyanide (acting here as a silver bleach) will convert a thin layer of metallic silver back into transparent silver salts and the fixer will remove the silver salts so they don’t turn metallic and opaque again when exposed to light. The second tray of water is for you to flip and briefly wash the negative in before you lift it out and hold it against a light to see if the fogging is reduced. (Otherwise, droplets of the potassium ferricyanide will continue to act on the film as you are studying it, creating a blotchy effect.) If you are reducing fog on a number of negatives, you will need to replenish the potassium ferricyanide as it loses potency and its yellow color but the fixer may not need to be replenished. The potassium ferricyanide weakens over time, as well as use, so replenish every half hour regardless of use. Many a fogged or over-exposed negative has been rendered useable by this free-wheeling procedure.

From Small-Format Negative to Interpositive to Enlarged Negative

Regarding contrast, you can compensate for deficiencies in your small-format negative as you first project it to obtain the interpositive and then again project the interpositive, or contact print it, to obtain the requisite large negative. It makes sense to burn and dodge as needed on the interpositive as you would on enlarging paper.

When you are enlarging an interpositive film from a very contrasty small negative (that would require grade 1 or 0 enlarging paper or the corresponding filter with multigrade enlarging paper), a film developer would work well. For a normal rendition of a normal negative that you would enlarge onto grade 2 or 3 paper, paper developers, which are more active than film developers and give denser highlights, work well. If the projected negative is thin it is OK to make a rather flat interpositive using normal dilution paper developer (or only somewhat diluted) but when you make the enlarged negative you can boost contrast without losing detail by using a more normal or even more concentrated paper developer and, if necessary, extending development time.

Copy Camera

A copy camera allows you to obtain in one step an enlarged, reduced, or same-size negative of whatever you put on the copy stand. A copy camera is essentially a large view camera, either vertical or horizontal, that can provide a negative, on the film or enlarging paper of your choice, of anything placed within the coverage of its lens. You can make a large negative in one step by exposing a finished photographic print onto sheet film. The advantage of exposing a finished print onto film (in addition to the time and film it saves since an interpositive does not have to be made) is that dodging, burning, bleaching and spotting can be accomplished ahead of time on the finished print. A disadvantage is that reflected light from a print does not contain as much tonal information as light transmitted through a positive transparency so a copy camera negative may not have the range of densities of a negative made with a film interpositive.

Flat work other than photographs, such as drawings, paintings and collages, may be translated into negatives in a copy camera too.

Three-dimensional forms can be photographed onto negative film with a copy camera. It has become a rite of passage for non-silver students to endure the blinding light and prolonged pose necessary to have large-format portrait negatives of themselves made on the copy camera at school. The lens is usually shut down for greater depth of field and exposure times are increased correspondingly. The resulting images have an uncanny presence and sense of volume. See the chapter on “Instructions for Copy Cameras”, for more information about using copy cameras.

DUPLICATING FILM — This kind of film is described for those who may have some in stock. At UArts we still have a good supply of free high-contrast duplicating film donated to us by the American College of Radiology when they went digital.

With duplicating film it is possible to obtain a continuous-tone negative directly from an original negative in one step. It works best when making a contact copy of a large- format negative in an ultraviolet exposure unit designed for that purpose which was also donated to us. It is great for duplicating precious view camera negatives and glass plate negatives as well as for making denser or thinner contact negatives. Fixed negatives of varying densities of flat photogram materials can be made too.

It is interesting to know about the far side of the characteristic curve and helps in understanding the phenomenon of solarization. This film has been pre-exposed by the manufacturer to the point where it is on the top, the shoulder, of its characteristic curve. Additional exposure will send it down the seldom represented far side of its curve, opening up the film instead of darkening it. This is basically what solarization is. (Sometimes a brief exposure of the orb of the sun in a pinhole camera will look on the film like a dark halo that is clear in the center where it got the most intense exposure and I imagine that the term ‘solarize’ comes from observation of this phenomenon.) You will know you haven’t given the duplicating film enough exposure if it comes out too dense.

Like ortho lith film, duplicating film is orthochromatic but less light-sensitive. The same red safelight (1A) is recommended for it but even amber light is useable since the emulsion is so slow. Unlike lith film, some duplicating film does not have a red dye anti-halation backing. It can be exposed through either side, but it is useful to be consistent about which side of the duplicating film (referring to notch position) you expose onto when making the enlarged negative since exposure times can slightly different from one side to the other. You may need to mark or notch your test strips to know which side is which — once the corner with the manufacturer’s notch has been removed.

Develop duplicating film in full strength or extra concentrated paper developer to maximize contrast. Lack of contrast is common with this film. Our supply of duplicating film is quite old and the paper developer needs to be very concentrated like 1:3. Farmer’s Reducer equivalent may be useful later to remove any fogging on the negative.

PAPER NEGATIVES from the Chemical Darkroom — Black-and-white photographic paper can be used in various ways to make large negatives. With prices for sheet film as high as they are (and the discontinuance of many of them), paper seems an increasingly attractive alternative. The paper negative prints in non-silver with a broad, sculptural, fibrous look reminiscent of the beginnings of photography.

It usually takes longer to expose material sensitized with non-silver chemistry through a paper negative than through a film negative because the fiber of the paper blocks much of the actinic light (although sometimes a film negative has so much fogging that it takes longer). When using the sun as a light source, the fibrous density of a paper negative is not much of a drawback. For instance, a cyanotype that takes 5 minutes to expose with a normal film negative might take 10 or 15 minutes with a resin-coated paper negative. A way to shorten exposure time with resin-coated paper is to separate the plastic emulsion layer from the paper base by carefully peeling the layers apart. Some workers have found that soaking the print in warm water facilitates this separation. The resulting, often uneven, plastic emulsion layer with residual paper fiber attached to it sometimes curls and can be hard to handle but, as printmaking major Mortimer Hechavarria discovered, the curl can be straightened by folding clear or frosted tape along the four edges of the emulsion layer. Sometimes the rough look of residual paper fiber adds charm to the non-silver print.

Registration of a paper negative on top of a multi-layered non-silver print is somewhat more difficult than with a film negative but it can be done by eye on a light- table if a dark color is printed first. The non-silver print should be taped down, the negative placed face down on top, and a tube of black paper used to block out all light except what is coming up through the sandwich of positive print and negative. The tube can be moved about to make certain that already-printed areas lie within the open parts of the negative. You may, however, need to use some other kind of registration such as marking the printing paper with pencils at the corners of the paper negative after you print your first layer. With a straight-edge you can extend these marks into the print margins (in case the second layer of emulsion covers and obscures the actual corners of the film).

A paper negative can be made on the copy camera with enlarging paper in the same manner as a film negative, with flat or three-dimensional material as subject matter. The exposure for creating a paper negative may need to be 2 stops more than for lith film.

Enlarging paper works well in pinhole cameras providing negatives that print especially well in gum. In oatmeal-box cameras and very shallow pinhole cameras, use paper with matte, pearl or luster surfaces to prevent the internal reflections (sometimes baffling and ghostly) that can occur with glossy paper. Multigrade paper is sensitive to green light, as well as blue, so that it renders foliage better than graded paper. Resin-coated paper works nicely. Double-weight fiber paper is too dense to print through. There used to be a single-ply fiber enlarging paper by Kodak called Polyfiber-A that was perfect for pinhole negatives. It had a fibrous, tactile quality and lent itself to tearing, cutting and collaging. I have tried other single-ply fiber papers that I’ve come across and have not been as happy with them. They all seem to have a clay coating that makes it hard for actinic light to penetrate the paper negative and form an image in non-silver.

You can draw or paint on paper negatives to strengthen highlights, eliminate shadows or otherwise modify the image. Turn the paper negative emulsion side down on a light table and work on the back of the sheet (assuming that the back of the print is fibrous and not a slick resin). Red or orange pencils and washes are especially effective in holding back actinic light. (Film can be scratched open on the emulsion side and painted on either side but is too slick on the back to draw upon with normal pencils.)


Digital halftones with very smooth tonal gradations can be produced by a Scitex imagesetter that was donated to the I-Lab at UArts. A high-contrast lith film is exposed by very fine laser beams and developed in a mechanical processor with darkroom chemicals to produce a digital halftone negative. The halftone grid of 200 lines per inch (each line being a 4 x 4 dot grid) is scarcely visible when you make prints from these negatives in cyanotype, vandyke or palladium, and is invisible with duotone renditions of those processes or multiple layers of gum emulsion. Other imagesetters (including Scitex), located at service bureaus, can print very fine random dot images with a resolution of 2400 dots per inch or higher, close to or surpassing the grain pattern of silver on film. Unfortunately, nowadays most offset litho plates for which the imagesetter was developed are photo-sensitized and are exposed directly by the laser beams so the imagesetter is going extinct.

DESKTOP NEGATIVES – Being able to make digital negatives at home or in a computer lab at school, instead of having to go to a service bureau, is a goal of many non-silver printers. Dan Burkholder’s book, Making Digital Negatives for Contact Printing (see “Resources“) has advice on making desktop negatives that have influenced many of us. Included in this edition are descriptions by Sandra C. Davis and by Melissa Good of how they make desktop negatives.

Desktop negatives can be produced in inkjet on Pictorico or Ink press transparency film and used with non-silver with curve adjustments made for different processes (see ‘Curves’ by Sandra Davis). With varying results, inkjet negatives can be printed on vellum or even inexpensive computer paper. This works best with gum printing. Also an inkjet positive can be enlarged into a negative on lith film on the copy camera.

Photo senior Alex Miller found someone at Staples who produced flawless unbanded laser negatives for him from enlarged scans of insects that printed remarkably well in palladium. Other students have printed successfully in gum from less perfect laser CMYK negatives. The multiple layers made the banding less obvious.

The future of non-silver processes is probably inextricably linked with the production of inkjet and laser negatives.

Read the next section of the book.

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