Carbon printing is a slow and complex process that requires a great deal of preparation. Some of the materials required are not so easily available; and due to fact that I wanted to explore an alternative formula, I made a decision to make my own.
I decided to make the pigment for each image using a formula that consists of Indian ink and locally sourced charcoal dust. The trees that I am photographing therefore create the very pigment that produces the final images. This is a fascinating concept to me. An image of the tree created from the tree.
Preparing the Photo Gelatin solution.
Photo Gelatin and pigment ready to be mixed.
Heating up the gelatin solution to 40°c and adding the Indian ink.
Here I am pouring the gelatin solution into plastic cups, which will be used later to make the carbon tissue paper.
Coating the paper
Sensitising the paper
Making the sensitising solution using Potassium dichromate. When the carbon tissue paper is coated with this sensitiser it becomes sensitive to UV light and allows the pigmented gelatin to react to sun light.
Making the prints
This process is beautifully simple in theory however in practice the realities are very different. This said, when a delicate carbon print has been made it is made forever! It will outlast any of the photographic processes. It is a very special way to make a photograph
The Carbon image is deposited on the paper surface as a photograph due to the fact that it was proportionately hardened when exposed to UV light through the 8 x 10 negative.
The image produced in a carbon print comprises of pigment suspended in gelatin (pigment paper) placed on a final support, usually paper. To make this image, a negative is placed in contact with a sensitized sheet of pigment paper and exposed with an ultraviolet light source. This causes the gelatin to harden directly in proportion to negative densities, i.e. the carbon pigment paper is hardened more in the shadows than in the highlights. After exposure the paper is soaked briefly in cool water, then squeezed into contact with the final support. This combination of pigment paper and support are removed from the water dish and left under pressure in blotting paper. After 30 minutes the pigment and support are transferred to a tray of 20°C water where the gelatin slowly absorbs water. After 3 minutes the temperature is gradually increased to 42°C This is where the development of the image begins. At 37°C the gelatin will begin to dissolve. Once the pigmented gelatin has begun to melt the tissue is peeled from the support and discarded. The unhardened gelatin slowly washes away from the support leaving a relief image.
After exposure, the carbon paper is sandwiched under cold water with the final print paper. As the gelatin from each surface absorbs water it swells and this creates suction making the carbon paper adhere to the final print which in this image is Velin Arches hot pressed paper. The final print paper needs to be gelatin sized in pre production to allow the carbon paper to stick! The gelatin size must be totally insoluble otherwise the final beautiful carbon image will just slide off the paper and will be lost forever! This is a sad thing to witness, trust me.
The paper sandwich is left to sit under light pressure for 15 minutes. It is then placed in water at 25°C to pre soak, this is where the developing begins.
I am developing the carbon print in water at 40° to 45°C. The temperature was raised gently to allow the gelatin to absorb the heat evenly. At 37°C gelatin dissolves, so it is the warm water action that washes or rather dissolves the non-image making black gelatin away revealing the sublime tonal qualities of the carbon print on the paper surface.
As the black gel warms it begins to ooze from around the edges of the carbon paper. At this moment the carbon paper can be peeled away revealing the gorgeous black gelatin on the final print paper. As development continues the soluble gel dissolves away and leaves beneath a delicate photograph made from carbon pigment suspended in photo gelatin. In my view a sight that every printmaker/ photographer should experience at least once!