Photographic Techniques

Utilized by Group Members (Chronologically Sorted)
Over nearly two centuries of photography's development and exploration, hundreds of different photographic techniques and their modifications have been experimented with. Many of these techniques lack established translations into Czech, and we sometimes encounter incorrect designations for the most well-known methods (for instance, when digital inkjet printing is referred to as "pigment").

Salted Paper
This term refers to a direct copying paper where the image is formed by fine silver particles directly within the fibrous structure of the paper. These images become visible already during contact copying of negatives. The process based on the conversion of silver nitrate to silver chloride (either ammonium chloride, or potassium chloride). William Henry Fox Talbot first used this process in 1834, and it remained in use for the next 25 years. It experienced a revival around the turn of the century during the artistic photography movement. Salted paper photographs, lacking an emulsion layer tends to be bland, therefore often served as a base for additional painting.

Cyanotype is a direct copying technique based on the light sensitivity of ferric salts. John Herschel first described this process in 1842, and Anna Atkins utilized it a year later in the first book illustrated with photographs. The sensitive layer of cyanotype contains ferric ammonium citrate and potassium hexacyanoferrate, which exposure to UV light reduces from ferric ions to ferrous ions, resulting in compounds of bright blue colour known as Berlin blue and Turnbull's blue. The process doesn't require a developer or fixer, making it relatively straightforward, and the resulting images are very stable. Toning can transform the blue images into other colours.

Van Dyke Process
The Van Dyke process is a direct copying technique based on the photosensitivity of ferrous salts. In this method, a sensitizing solution containing ferric ammonium citrate, silver nitrate, and tartaric acid is applied. During UV exposure, the ferrous ions reduce silver ions, resulting in the formation of metallic silver. The resulting image appears as a brown tone and is not on the surface but rather embedded within the paper fibres. This process was first described by John Herschel in 1842, similar to cyanotype and argentotype. William Walker James Nicol further elaborated on it in 1889 and patented it under the name "kallitype" (as discussed below). The Van Dyke process is relatively straightforward, cost-effective, and yields satisfactory results. After exposure, it is processed in plain water and fixed using a typical sodium thiosulfate solution. Additionally, images created using the Van Dyke process can be toned and may be produced on materials other than paper, like cyanotypes.

Gum Bichromate Print
The gum bichromate print technique is based on the photosensitivity of chromated gelatine and gum Arabic. It falls into the category of Pigment printing photographic processes (sometimes inaccurately referred to as "prints"). In gum bichromate printing, a solution of gum Arabic mixed with potassium dichromate is applied to paper. Typically, this mixture is coloured with powdered pigment, watercolour, or tempera paint. After exposure, the print is developed in water, and no fixing step is necessary. While the method is straightforward, it requires practice, precision, and patience. Achieving well-defined images with rich tonal variations in highlights and shadows often involves multiple layers of exposure. Alphonse Louis Poitevin invented this technique and pigment in 1855. Gum bichromate printing was particularly popular during the era of artistic photography ( Art Nouveau pictorialism) around the turn of the century.

Pigment Printing (Carbon Print)
Pigment printing based on the photosensitivity of chromated gelatine. Alphonse Louis Poitevin invented this process in 1855. In pigment printing, suitable paper is coated with a layer of gelatine containing dispersed pigment. When carbon black or soot is used as the pigment, it is specifically called "carbon print." Before exposure, the sensitized paper is treated with a potassium dichromate solution. After exposure, the exposed paper is soaked and pressed against a receiving sheet which is covered with a layer of pure gelatine, thus the layers of image are overturned and it is possible to wash out the rough spots with water, i.e. the ones that were not affected by light. Pigment printing can exhibit a wide range of halftones, velvety matt surface and fine relief. From pigment printing photographic processes, the pigment printing began to be used at the beginning of the era of art photography at the turn of the century as the first, especially in the last decade of the 19th century.

Platinum Print
Platinum print is a technique based on the photosensitivity of iron salts mixed with platinum. The resulting image exhibits beautiful, rich brown to blue-black tones without absolute black. Platinum is selectively deposited to create the image. Due to the expensive materials used for sensitization, this technique is costly. The image is developed using a potassium ferricyanide developer and washed in a bath, usually containing diluted hydrochloric acid. William Willis is credited as the inventor of platinum print, and it was patented in 1873. Although once the most durable photographic technique alongside photoceramics, it fell out of widespread use due to the rising cost of platinum during the Great War. Today, its platinum-palladium modification remains popular.

Printing Out Paper (POP)
Printing Out Paper refers to directly copying papers that produce a visible image without chemical development. After exposure, the paper is washed in water and then fixed. The image is created using silver salts dispersed in an albumen, collodion, or gelatine emulsion. The entire process, from exposure to the resulting reddish-brown image, can be observed in a contact printing frame. Various types of directly copying papers, including albumen-based, collodion-based, and later gelatine-based (known as aristotypes), were typically toned using gold and platinum salts. This allowed for a diverse palette of shades, ranging from red to sepia and even black. The foundation for this technique was laid by salted paper, and the term "Printing Out Paper" was introduced with the gelatine-based directly copying paper by Ilford in 1891. Over time, these papers were gradually replaced by gelatine silver bromide developing papers coated with a barium sulphate layer, which are still used today.

Kallitype is a directly copying technique based on the photosensitivity of iron salts combined with silver. In principle, it is similar to the Van Dyke process. However, Kallitype is more demanding and expensive because it uses ferric oxalate instead of ferric ammonium citrate for sensitization. After exposure, it requires development in a specially prepared solution. William Walker James Nicol is credited with inventing this technique in 1889. The resulting image comes out in brown shades and can be toned. Kallitype images achieve results similar to the more expensive platinum prints.

Oil Print
Oil print is a technique based on the photosensitivity of chromated gelatine, sensitive after drying the gelatine solution with potassium dichromate. It is similar to gum bichromate and pigment printing. However, oil print differs in that colour is applied afterwards, optionally. In contrast, gum bichromate and pigment prints have colour applied before exposure. After exposure, the image is soaked, and unexposed areas swell with water. The resulting relief and image are then made visible using printing ink applied with special brushes. Among pigment printing photographic processes, oil print allows the most significant control over the final result. Emanuel Mariot and, notably, George Ernest Henry Rawlins are credited as inventors of oil print in 1904.

Bromoil Print
Bromoil print is a technique similar to oil print, but it uses silver bromide black-and-white enlargements obtained through standard analogue processes on industrially produced photographic paper. However, the developed gelatine positive must be bleached and hardened before working with it, similar to oil print. The colour of the artwork also depends on the oil paint used. An advantage of bromoil printing is that it does not require contact printing (matching the dimensions of the negative), which is typical for other processes mentioned here. Edward John Wall & C. Welborne Piper are credited as inventors of bromoil printing in 1907.

Argyrotype is a technique based on the photosensitivity of ferrous salts to light. It was first described by John Herschel in 1842 under the name "argentotype,". However, the resulting image was unstable. In 1991, Mike Ware revised and simplified the original process, improving its stability, and named it argyrotype. This technique also belongs among those where we can see an interesting brown image already during exposure.

Overview compiled by Pavel Scheufler