My name is Xosé Gago Pesqueira, and I was born in August 1946, a year of which I remember nothing and of which I can say nothing, and therefore, I do …
Workshop of Direct Carbon Print process
Direct carbon is a quite different technique of carbon transfer, and is performed entirely on the final image support, without intermediate steps such as the transferred carbon technique requires. The final images are similar in part, but according to the method used to produce it by the method of direct carbon, can be completely different from the transferred image in its visual presentation. The particularities of both images come from the different kind of handling that the two carbon copy systems need to be carried out, that are completely different in both techniques.
On the other hand, the beauty of both types of images depend on many different factors, and you can not make a comparison between both types of pigmentary procedures to decide or chose, except personal issues, such as the influence of emotions and feelings, the type of manipulation that might like more or less to two more different people, and other finishing technical-aesthetic factors or personal intervention on the copy, which are huge in direct coal, and practically null in the coal transported.
Direct carbon has always been an industrial production in history, unlike the gum bichromate process that was always the personal photographer’s work and where he had to prepare all the materials himself. There was one exception, the Hochheimer paper, an industrial paper which was “gum” and so was called and known. But other than this case, all other papers were “gelatin” although prepared in a special way to give midtones, as gelatin, by itself and without transportation, can not give them due to physicochemical reasons.
There were two industrial methods for pigmented papers, and it is assumed that all manufacturers used the same, and only the house Artigue employed “the other”: The pigmenting Artigue system was to give a thin layer of unpigmented gelatin on paper, and then, once the gelatin lit or coagulated, but before complete dried, it was passed again through the machine between brushes that deposited the pigment by brushing the surface.
The Fresson system and any other else was just mixing first the gelatin with the pigment until a smooth emulsion was obtained and, then it was spread on the paper by the machine. The Artigue system, carrying the pigment only on the surface of the emulsion gave completely dull matte images, and this paper was also called “velvet paper” by this feature. The Fresson paper and others were much less matte, and they could even have a certain brightness varying with the sort of pigment used.
The historical paper were sensitized in a bath of ammonium or potassium dichromate (or mixtures of both, by some researchers) and once dried were exposed to light, and then developed, after a soaking them in a water bath at about 35 ºC, “by gravity” with a stream of sawdust. That is, using the “technique” of using a mixture of water and sawdust around 35 ºC , and dropping it from a container kept handy at certain height, and directing the flow as the emergnece of the image “were asking for” by the friction of the sawdust against the exposed surface of the paper. This “stream development”, however, can not be called “chemical development” because there is no chemical reaction in it, but a physical “smallbattle” of the sawdust against less hard gelatin paper exposed that only “polish” the low exposed gelatin within its potential insolubilization reliefs by the light. The development of chemical emulsions could, of course, be described as “chemical developed” because, all of them really consist of one, or rather of some chemical reactions that make emerge the image.
Carbon and gum bichromate images, if made with mineral pigments, are the most stable of all known photographic processes, and which can resist as long as the duration of the support on which are formed. They exceed in stability the platinum processed, even though almost everyone believes otherwise. (Platinum attacks and destroys, on the long run, the paper base).