The history of the Bromoil Process

The Bromoil Process came into being in 1907 when a photographer, C. Welbourne Piper, wrote an article in a British journal which illustrated how to produce what was essentially an oil print on Bromoil Paper. In this a bromide print, which had the advantage of being able to be enlarged, was used as a basis for inking. Two actions were then necessary; the bleaching away of the silver image and the hardening of the gelatine in proportion to the amount of silver.

Several formulae became available, most of them involved the potassium salts ferricyanide, bromide and bichromate. As with the Ozotype and derivative process the ferricyanide bromide bleached the image, whilst the bichromate chemically hardened the gelatine in proportion. After treatment the print was washed, fixed in acid hypo (which cleared the final trace of the image and unused potassium bichromate) and, finally, washed and dried again. The print was then treated as an oil print, swelled with water and dabbed with pigment. This was also referred to as the Ozobrome-Oil process.

The very basics of the Bromoil Process started alot earlier than 1907. In 1839 a Scottish photographer called Mungo Ponton gave a paper to the Society of Arts of Scotland, in which he outlined a cheap and inexpensive method of producing an image without the use of silver. The problem was that the image he produced was brilliant yellow in colour, which obviously didn't catch on very well, but he did start a train of thought in the chemical he used; potassium bichromate.

The basic technique of the Bromoil Process

In brief, the starting point is a suitably exposed negative that is printed onto an appropriate black and white paper. The print is fully and cleanly developed before being bleached and tanned. When these processes are complete, there will remain only a pale shadow of the original picture.

The paper is then soaked in water, which is absorbed by the gelatin in amounts that vary with the different tonal densities of the original silver image. After wiping off excess (surface) water, a stiff oil-based ink is applied using a firm brush. The ink is held to greater and lesser degrees in areas that have absorbed different amounts of water. Eventually, a visible image will appear.

Contrast and density can be adjusted as necessary, leading to a final ink-based print with whatever qualities are required. Were it not for the gelatin substrate, the final picture would be as stable as any other ink-based image. The final touch, therefore, is to transfer the ink image onto a new, pure paper, support (Bromoil Transfer). The end result is a print that should possess exceptional archival properties thanks to its immunity from chemical attack.