Discovery

The carbon printing process was a more permanent form of printing than the albumen prints which tended to become yellow and fade. In 1839, Mungo Ponton discovered that writing paper soaked in a solution of bichromate of potash was sensitive to light and turned brown in parts exposed to the sun. Hunt (in 1843) and Talbot (in 1853) also suggested processes using bichromate of potash. In the late 1850s, experiments were carried out by several photographers including Pouncy, Sutton and ultimately Swan. the following year. But it was not until 1864 that the process became more widely used. Sir Joseph Wilson Swan introduced improvements to the carbon printing process, and patented his method on 15 April 1864. Details of the patent are given in the book Carbon Printing by EJ Wall. The carbon process was used by the Autotype Company from 1866 until the end of the century. Recent Work I hear from Kevin Sullivan of Bostick & Sullivan, Santa Fe, New Mexico, USA, that there are still a handful of skilled workers in the carbon process. The Bostick & Sullivan web site includes some details of carbon coating techniques. However, for further information, Kevin recommends the web site of the Rocky Mountain Photographers Forum Carbon Group. He also recommends the following two books, the second of which he describes as a good practical manual that describes a good method of making the tissue. - History of Carbon and Carbo [Luis Nadeau] - Carbon and Carbo [Sandy King] Process Overview The carbon process consists of: a) printing a negative onto a tissue containing carbon and other pigments in a gelatin base, previously made light sensitive in a bath of potassium bichromate.. b) transferring the image to a paper base and stripping off the backing of the tissue. [The American Museum of Photography] Detail - step 1 A sheet of carbon-impregnated gelatine is obtained. It was recommended that photographers should purchase commercially prepared paper, rather than try to prepare their own paper. However instructions for photographers who wished to create their own tissue were given. The following was said to be sufficient to coat a sheet of tissue measuring 3.6m x 0.76m (132 x30 ins) a) Soak 25 gm Nelson's gelatine in 675cc water by the aid of a gentle heat. b) Add 30-60 gm sugar and 25gm dry soap c) Filter d) Mix with colouring matter The ingredients required to make a variety of colours were given. Reddish brown required: - Indian Red 10 gm - Carmine lake 6 gm - Chinese ink 8 gm Reddish brown required: - Lampblack 3.8 gm - Carmine lake 4 gm - Indigo 2 gm Detail - step 2 This sheet is treated with a sensitising solution to make the paper light sensitive. The sensitising solution is made by dissolving 1oz potassium bichromate and 5 drops liquid ammonia (.880) in 20 oz distilled water. Dry the sensitised tissue, preferably in a drying box - alternatively in a room protected from light by blinds. Detail - step 3 This sheet is exposed to light under a negative, with actinometer paper beside the printing frame. When the actinometer paper has darkened sufficiently, remove the carbon paper from the printing frame. The coating on the carbon paper will have hardened in proportion to the intensity of the light that it has received, and an image may be just visible. Detail - step 4 The sheet is transferred onto a temporary support and the image is developed, using hot water. The unhardened gelatine is washed away, leaving what appears to be a conventional print, the darkness of the image depending on the thickness of the carbon impregnated gelatine remaining. Detail - step 5 Place the print in a bath of cold water> Fix the print in an alum bath, until free from any yellow tinge. This removes the soluble bichromate. The alum and the action of light also hardens the film. Wash then dry. Acknowledgement for the detail above: [Carbon Printing: EJ Wall: Amateur Photographer's Library No 8: 1894] Carbon Printing TODAY I have been told by Kevin Sullivan tells me that: a) Carbon printing is not now very popular. It is a fairly involved process, so a good book is recommended. However, there are still a handful of skilled practitioners. b) His company Bostic Sulllivan sells two books: - History of Carbon and Carbo [Nadeau] - Carbon and Carbro [Sandy King] - a practical manual that covers making the tissue and printing. c) His company has a page that describes a good method for making tissue but not the exact formulas. There are hundreds of various mixes on his site his site. d) The most active online resource is the Rocky Mountain Photographers' Forum Result Carbon prints can have a wide tonal range and retain their rich tones, offering a permanent image without grain. Musselburgh Fishwives © For these reasons, some photographers offered carbon prints, in preference to albumen. Carbon printing was also used for printing onto surfaces other than paper. Prints on opal glass could look particularly attractive.

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