(See also Photographic Treatises
written by China including – Strengthening Dichromates
, The Silver-Selenium Process
, An Important Simplification of Gum Bichromate
, Gold Enhancement of Silver Chloro Bromide Prints
and Resolution of the Weaknesses of Iron/Silver Printing
1. China Process or China Prints (Bleaching) or the “Silver Selenium” Method of Print Toning with Iodine
This process takes a selenium print and bleaches it – a selenium to bleach technique. It is an archival process and the type of aesthetic it produces is especially attributed to China’s work.
China published this method of print toning in Ag Photographic Volume 4 (1993): ‘The Silver-Selenium Process’
” Much work on the above technique has been done by Liam Lawless, who together with China Hamilton – from whom this process takes its name – produced this variation by substituting ferricyanide bleach with iodine. Proprietary ‘Boots’ iodine tincture may be used, or an iodine reducer sold for photographic use, or made up from the formula below.
The initial reaction to immersing a print in iodine is likely to be one of shock, for iodine stains everything, including the print. This stain lifts when the print is transferred to the fixer however, and reveals reddish colours, which change with the time in the fixer. The print can be removed and washed at any stage and the slower ‘hypo’ may be easier to control than a rapid ammonium thiosulphate fixer. Attractive split tone effects can be produced by varying the time in the iodine or in the fixer. Once again, prints generally have to be overexposed by up to 1/2 a stop for best results.
Combination techniques using both ferricyanide and iodine may produce stronger colours if required. The permutations here are considerable and bear some experimentation.
Iodine bleach formula: Methylated spirits 100.0mls, Iodine crystals as much as will dissolve, Dilute 1+10 for use.”
2. Argentoferro Process (also Gold Argentoferro)
Developed by China, this technique is a definitive resolution of classic iron/ silver. The process is chemically archival and in comparison densitometer tests it produces good positive virtual blacks and long tones far in excess of platinum/ palladium.
Its virtues are simplicity, low print cost, low chemical hazard and consistently reproducible quality standards.
China published this process in The Journal of Photographic Science (1993): ‘Resolution of the Weaknesses of Iron/Silver Printing (Known as the Argentoferro or Argentotype or Argyrotype Process)’
3. Gelatin Chloride upon raw copper sheets
An individually made gelatine chloride emulsion as a nano-coating upon an inert oxide interface is directly applied onto a sheet of copper. It is printed out and toned with gold and/ or selenium. The copper sheet is then decorated with controlled oxidation. Watercolour paint and ink were sometimes added by China as additional decoration
This is an archival process and China was the first to demonstrate the possibility of printing photographically directly onto sheets of copper. China was particularly adept at this process and the type of aesthetic it produces is especially attributed to his work.
4. Gelatin Chloride upon handmade paper
A suspension of silver salts in gelatin is coated onto hand-made paper onto which a resin coat would be manually applied.
5. Gum Bichromate
(China’s simplifications of the process, known as The Dichromatype or Hamilton Gum Bichromate)
The paper is brushed with a coating of gum arabic, water, finely ground pigment and potassium (or ammonium) dichromate, and usually exposed to sunlight or to an ultra-violet source, in contact with a negative. Brushing or washing the surface could dissolve areas of the coating hardened more or less by exposure, thus changing contrast and adding effects reminiscent of drawing or painting
China undertook improvements to the process, which were published in –
a) The Photographic Journal (October 1993): ‘An Important Simplification of Gum Bichromate. The Dichromatype’; and
b) Printmaking Today. Volume 5 Number 2 (1996): ‘Strengthening Dichromates (China Hamilton describes his improvements)’
6. Albumen Dichromatype
An albumen print was made by coating paper with a layer of egg white and salt to create a smooth surface. The paper was then coated with a layer of silver nitrate. The salt and silver nitrate combined to form light sensitive silver salts.
This double-coated paper could then be placed in contact with a negative and exposed to the sun to produce a print.
The above was often toned as part of the final process, most usually with gold toner (a Gold Chloride, Sodium Acetate and water mix).
7. Gold Kallitype (Argentotype)
Iron salts (ferric citrate) are used to precipitate silver under the influence of UV-light. The print is developed in silver nitrate.
8. Gold Sun Print (also Gold Solachromatic)
9. Gold & Selenium Toned
Metal replacement toning, using a combination of selenium and then gold toner that creates a more archival image than either toner separately.
It results in a fine blue-black tone. The Selenium impacted the D-Max areas and the Gold further impacted and protected the highlights as well as impacting the D-Max areas.
10. Iron Toned
Metal replacement toning using iron toner that produces a blue tone. It is not very archival and therefore can impact print longevity, so was only done for aesthetic reasons.
All metal replacement toners replace the metallic silver, through a series of chemical reactions, with a ferrocyanide salt of a transition metal. Some metals, such as platinum or gold, can protect the image. Others, such as iron (blue toner) or copper (red toner), may reduce the life of the image.
It is sometimes used to split tone photographs previously toned in selenium for artistic purposes.