Bromoil Process
In 1907, working from the research of Howard Farmer and E.J. Wall, C. Welbourne Piper publicised the working details of a process that produced an inked image from a silver bromide paper print. A non-supercoated paper print is treated in a dichromated bleach solution, converting the silver image back into silver bromide. The bleaching bath also hardens or tans the gelatine in proportion to the amount of silver present. The print is washed in water, swelling the gelatine into a relief matrix that will accept greasy ink in the shadow and mid-tone areas, but repel it in the highlights (where the water content is highest). Once the matrix has been drained and blotted, the original photographic image can be inked up with a large blunt-cut brush, or small rubber brayer. Bromoil transfer is a variant of the above wherein the inked matrix is printed onto a second sheet of paper. A mangle press or the back of a spoon can be used for the transfer, which is suitable for colour work as a series of selective matrices can be printed in register to produce a coloured image. (see Bromoil Video & other products, p.67)

THE PROCESS

Paper- Kentmere Art Document bromide enlarging paper, contrast grades 2 or 3 Print the bromide print for both highlight and shadow detail, printing somewhat darker and flatter than usual. Develop, wash (do not use stop bath) and fix using the solutions below, and wash thoroughly.
Developer - use a developer having a minimal hardening effect on the gelatine of the paper: Amidol and Sodium Sulphite, or: Kodak Dektol diluted 1 part developer to 10 parts water.
Fixer- without hardeners. A basic fix should contain acidifiers but no hardeners. If in doubt, try Kodak F-24 non-hardening fixing bath or plain hypo (sodium thiosulphate) with sodium bisulphite. These fixers can also be used to fix the bleached print.

Bromoil bleaching bath
15 g copper sulphate 15 g potassium bromide 1 g potassium dichromate Mix in 375ml. distilled water, then top up with water to make 500ml. stock solution. Store in a dark brown bottle, away from heat and light. Dilute for use: 1 part stock to 3 parts water. Bleach in the bleaching bath until the image is a faint beige colour, and leave in the bath for half again as long. Wash thoroughly and fix as usual. A grey-ish image should be barely visible. Dry the print, and store away from light.

Inking
Adana letterpress inks or Charbonnel litho. inks. Add French chalk to increase tacky consistency, a solvent is extra-refined lighter fuel.
Soak the print in water at 20°C for at least 10 minutes. Place the print face up on a paper towel to blot water off the back, then face up on a smooth waterproof surface. A tilted sheet of melamine or plexiglass is suitable as an easel.
Blot the surface of the print (gently) with a damp chamois. Work over the print with brayer, covering entire surface quickly then more carefully redistributing and clearing highlights and mid-tones. Or, with a brush, start with a hard consistency of litho ink and hop this onto the entire surface of the print. Work over the print with shorter hopping strokes to redistribute the ink from the highlight to shadow areas. Once inked, the print will take about 24 hours to dry thoroughly.