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GENERAL INFORMATION

CHOICE OF PAPER

The information contained in this page is relavent to both these processes. For other particular details and an historical overview, visit each one of the respective pages.

The Cyanotype and Argyrotype processes, print on most art papers, but for best results and if an archival print is desiered, a good paper is recommended. A good paper is a paper that will always give you consistant results no matter which batch it came from or when you bought it.

The paper should be neutral in PH and should have on or in it an organic sizing. It should have a high rag content, normaly sold by its percentage of rag. Rag paper is made from cotton linter, the shorter fiber left from ginning the longer fiber for cloth.

Paper may be internally or externally sized. When paper is internally sized, the manufacturer adds sizing substances to the fibre mixture; with the externally sized papers, the sizing is applied to the surface of an already formed and dried sheet.

The sizing applied to paper can be organic or a mixture of clay, metallic elements, or synthetic materials.

A paper sized with organic materials is recommended, (arrowroot starch, corn starch, gelatine, carrageenan, glue, and casein are commonly used to size art papers).

Manufacturers also include in their products, other substances that may interfere with these sensitisers or attack the image lying within the paper fibbers.

Hand made papers are excellent but the price is much higher.

A paper of 120 to 300 gsm is recommended; light papers will clear and wash faster then heavier papers but they might be too fragile when handled wet. Heavier papers will take longer to wash but they are a lot more resistant.

Papers vary greatly in their texture which can be used for aesthetic purposes. While smother papers will produce a sharper image, and showing more detail, an extremely textured paper will collect sensitiser in the hollows and starve the peaks. When an image is printed in souch textured papers, it may show dark hollows and bold peaks. These papers may require more sensitiser then smooth papers and a brush should be used rather then a glass rod when applying the sensitising solution. Texture can and should be used to serve image presentation.

EXPOSURE

Both Cyanotypes and Argyrotypes are printed by contact and exposure is judged visually, therefore a contact printing frame is very useful. Contact printing frames allow to inspect the exposure without moving the paper and negative from register. Two sheets of glass can be used with success, providing the paper and negative are taped in register to allow for inspection. The exposure is done under any source of ultra violet light, of which the sun is the most readily available and by far the most safe and economical.

The image will appear on exposure, which is continued until the highlights show detail. When using an artifitial light source test strips can be made to determine the exposure with accuracy. UV fluorescent tubes, mercury vapor, small domestic sun lamps, domestic sun tanning equipment, and carbon arc lamps, or an expensive exposure system designed for screen printing are suitable light sources for contact printing.

HEALTH AND SAFETY

The Argyrotype and Cyanotype sensitisers are toxic if injested in quantity.

Store out of reach of children.

Spillage on skin and fabrics should be washed with plenty of water, or a stain will occour.

Protect eyes and skin from UV radiation emited by light sources.

Use curgical gloves, eye protection and apron.

Use tongs or curgical gloves for wet processing.

If inhalation ocurs, move the victim to fresh air in half sitting position and seek medical advice.

If the product is involved in a fire, toxic fumes and smoke may be generated, do not breathe these fumes.

In case of fire, any fire extinguisher is allowed, provided it is compatible with the surrounding materials.

Always use distiled water when mixing chemical salts and add chemicals to water, not water to chemicals.

COATING

Make sure the table you are using is leveled.
Tape the paper or textile to be sensitised onto a larger sheet of ordinary paper, avoiding this way staining the table and it will help keeping the art paper steady while coating.
Always use a larger sheet of art paper then the area intended to be sensitised, because it's easier to cut the excess in the end.
Coating is done with a brush or a glass rod. This procedure can be done under normal room light because Cyanotypes and Argyrotypes are only sensitive to ultraviolet light.
When coating, avoid getting any sensitiser on the back of the paper, any sensitiser reaching the back will be exposed by light coming through the paper and will form dark spots that may be visible in the print.
Coat the paper with a minimum amount of sensitiser, for its excess will make washing more difficult, and the sensitiser sinks more deeply into the paper fibers, resulting in prints that are less sharp.
Once the paper is sensitised, it should be dried in a dark place. If fast drying is desirable, a hair dryer on low heat can be used without risking any damage. Fast drying is ideal because it keeps the sensitiser on the surface of the paper.
The dried paper can be kept in a light tight box and exposed within a day or two, provided the paper used does not contain substances that might fog the sensitiser during storage. For best results, the paper should be exposed imidiately after drying. Any change in colour during storage indicates that a chemical reaction is taking place and the highlights will most certainely be chemicaly fogged.
COATING WITH A GLASS ROD - With the paper taped flat to a larger sheet of cardboard or ordinary paper, lightly mark with a pencil the area to be sensitised. Fill a seringe with the amount of sensitiser necessary (1.5 to 2 ml should be enough to cover an area of 8x10), and draw an even line of sensitiser on one end of the area already marked. With the glass rod, spread the solution with several gentle runs backwards and forwards until no excess sensitiser is seen on the surface of the paper. If apllying excessive runs or too much preasure on the rod, it will start scraping the paper surface which will show in the end as dark spots in the print.
COATING WITH A BRUSH - A very soft brush should be used. Prepare the paper as above and place the sensitiser in the center of the marked area.Quickly but gently paint the sensitiser up and down and left to right until no excess sensitiser is seen. Excessive brushing and using it a bit more roughly will produce streak marks.

THE NEGATIVE

A large format camera is defenatly the ideal way to produce a negative for contact printing, but not everyone has this facillity, although if you haven't got a large format, it's not the end of the world. There are other ways of producing a large negative.
By enlarging a 35mm or medium format on to KODAK professional direct duplicating film type so -339 that is available in 5x4 and 8x10 ins.
By producing an inter-positive using normal negative working continuous tone films such as KODAK Gravure Positive film 4135 or Agfa Gevatone N33p which are available in large sheet sizes.
Using sheets of lith film developed in a normal film developer diluted twice as much as the normal working dilution will produce a continuous tone film.
By scannig an image into a computer and inverting it to negative, you can print it on transparency film. A different field of imagery can be explored with computer manipulation.
A good photocopier will be able to invert an image from a photograph into negative and print it onto an overhead tranparency. This is a quick and economical way to produce a negative that sometimes it might be just what you need. (Raise the contrast in the photocopier)