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• 20 x 15 to 40 x 30 (large but not that large)
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Kallitypes

Kallitype is one of a number of printing processes in the iron-silver family along with many others, including vandyke brown and argyrotype. There are some similarities among these processes, but in kallitype the light-sensitive element is ferric oxalate; in vandyke and argyrotype it is ferric ammonium citrate. The ferric oxalate makes a superior process in several important ways: it permits darker shadows and it allows for extensive contrast control. The difference in density is not huge between these processes, but well-made comparison prints side by side usually show more richness in the shadows of a kallitype than in a vandyke or argyrotype. However, the greatest advantage of kallitype over the ferric ammonium citrate based processes is greater control of contrast, which makes it possible to print negatives with a wider range of densities than with either vandyke or argyrotype.

The basic theory of kallitype printing is found in Sir John Herschel's paper of 1842, On the Action of the Rays of the Solar Spectrum on Vegetable Colours, and on Some New Photographic Processes. However, it was not until 1889 that W. W. J. Nicol patented the first iron-silver process and he is widely considered to be the inventor of the kallitype. In Nicol's original patent, the print was developed in a silver nitrate bath. He patented several revisions in the early 1890s and in one of these formulas he recommends using silver nitrate in the sensitizer rather than in the developer. This last revision is the method used by most contemporary kallitype printers.

The Kallitype process at a glance
Kallitype printing is similar to platinum and palladium printing in theory and technique. However, the Kallitype printing process uses the less expensive silver salt in place of platinum or palladium salts. Good Kallitypes have a platinum-like quality. Print color can be controlled by development. Sufficient chemicals for black, brown, or sepia development are included in this kit.

Mixing chemicals
The Sensitizer
In a darkroom using a red safety light, add the solid silver nitrate to the ferric oxalate solution. Stir the resulting mixture with a glass or plastic rod to dissolve the solid. It is very common for a precipitate of silver oxalate to form. This precipitate does no harm. If your sensitizer does form a precipitate, just be sure you do not transfer it to the paper you will be coating.

The sensitizer must ripen for a few (2-3) days before use. Keep the solution in the darkroom and stir or mix it occasionally. The mixing is especially important if a precipitate formed during mixing.

The Developer Stock Solutions
Two stock solutions (called A and B) are to be prepared. With these two stock solutions, three types of developers can be mixed:

• Back-tone developer;
• Brown-tone developer;
• Sepia-tone developer.

The proportions of Stock Developer Solutions A and B needed for these three developers is described in the section on "Development".

Preparing the canvas
Paper, card, textiles or any other naturally absorbent material is coated with the solution and dried in the dark.

Printing the Kallitype
Objects or negatives are placed on the material to make a print. The Kallitype is printed using UV light, such as the sun, a light box or a UV lamp.

Processing and drying

After exposure the material is processed in a two bath process.

The final print is dried and admired.

Sensitizing the Paper:
Using a good brush and working in very subdued light or in a darkroom under a red safety light, brush the sensitizer solution onto the paper pinned to a board. The brush strokes should be from top to bottom and from side to side. It is not necessary to measure the amount of sensitizer used.
The amount of sensitizer needed will depend upon the porosity of the paper. In general you can expect to use about 1 ml for a 4-by-5 print (4 ml for an 8-by-10). Since this kit contains 30 ml of ferric oxalate which was used to make the sensitizer solution, you can expect to be able to make up to 30 4- by-5 prints (or about seven 8-by-10 prints).
Allow the sensitized paper to dry in the dark. The drying of the print can be speeded-up by using a hand-held hair dryer. DO NOT OVER HEAT THE PRINT.

Exposure
Ferric oxalate absorbs in the ultraviolet region of the spectrum. Therefore we will be using the UV exposure in the Printmaking lab.

You must run a test strip to calibrate your print exposure..

Development
Formulas for three different developers are described below. You may wish to experiment with intermediate mixtures of your own. In general, if you increase the amount or proportion of Stock Developer Solution A (Rochelle salts) in the developer, you will increase the sepia-tone of the print. If you increase the amount or proportion of Stock Developer Solution B (borax), you will increase the blackness of the print.
Print contrast of any of these developers can he increased by adding 5 to 20 drops of 10% potassium dichromate solution per 500 ml of the mixed developer.

Final Steps
The final clearing, fixing and washing will determine the quality of the final print. For the print to be stable, the iron salt, the excess silver salt, and all the thiosulfate (used to remove the silver salt) must be removed.

Clearing: Soak the print in the potassium oxalate clearing-bath for 5 minutes at 20°C/68°F. Drain the solution from the print, give it a quick water rinse, and then transfer it to the thiosulfate fixing solution.
Fixing Soak: Soak the print for not more than 5 minutes in the sodium thiosulfate fixing bath, a longer soak will cause the print to fade. Do not use a standard photographic fixing bath; the finely divided, unprotected silver metal will be etched from the print.

Final Water Wash:. The thiosulfate just introduced must he completely removed to ensure print stability. Wash the print for 40 minutes in running water (20°C/68°F). A more effective procedure is to wash the print in running water for 2-4 minutes to remove the bulk of the thiosulfate, then use Hypo-Clear (cat. no. 03-0165), followed by a 15-20 minute water wash.

Potassium Oxalate: is an anticoagulant (prevents blood clotting) and a poison. Since this chemical is used as the clearing bath, it can easily come into contact with your skin. It is strongly advised that you use tongs to clear Kallitype prints or wear rubber gloves if you feel you need to handle the prints during clearing.

Should potassium oxalate solution come into contact with your skin, wash immediately with soap and water.

Ammonia (28%): Concentrated ammonia is also called ammonium hydroxide. This liquid releases extremely choking ammonia gas when opened. NEVER SNIFF THE LIQUID. Always keep any container with a solution of ammonia well capped. In the Kallitype process, ammonia is used in the fixing bath. Mix this bath in a well-ventilated area.

Potassium dichromate is both toxic and an oxidizer (potential fire hazard). To dispose of excess solid potassium dichromate, always wash the solid down a drain with copious amounts of water. Never dispose of the solid in a wastepaper basket.

Spillage of a dichromate solution on the skin will cause a chemical burn, which will appear as ulceration. In addition, all chromium compounds are potential carcinogens. We strongly advise you to use disposable rubber gloves when handling this compound or its solutions. Clean all trays and containers thoroughly with water, followed by soap and water. Dispose of excess dichromate salts and their solutions down a drain with large a volume of water.