Bergger PMK Film Developer
PMK Liquid Developer 250ml A + 500ml B to make 25 litres of working solution
Pyrogallol developer (Gordon Hutchings formula)
Short Historical Aspect
Pyrogallol was the most popular developer in the 19th century. Although it was considered the best developer, it was difficult to use. With the discovery of easier to use developing agents such as génol (1891), pyro began to lose popularity. Nevertheless in the 20th century photographers as Edward Weston go on to use pyro in the tradition of fine art. Nowadays, the constant search for improved technique in the expressive craft and fine art aspects has created a renewed interest in the use of pyro.
Aesthetic Advantage of PMK
Pyro can provide a definite increase in both the printing quality of the negative and its capacity to record subtle differences of light. Sharpness, acutance, highlight separation and the masking of the inherent grain, are properties of the negatives that show immediate improvement.
Pyro reveals its magic in more photographically difficult or subtle light. Early morning, late evening, bright lights, strong backlight, very detailed highlights and all atmospheric effects will be enhanced by pyro. Acutance and tonal separation are more evident throughout the negative image. Because pyro affects film differently than other developers, the elements of t he film/developer relationship are important.
Pyrogallol is in solution A and solution B is made with Sodium Metaborate. After a week or two, the colour of stock solution A will turn a pale yellow colour. This is the equilibrium point and no further change will occur. The shelf life of the stock solutions is exceptional. Partially filled and stored bottles will last 10 years or more.
Working Solution of PMK
1 part A + 2 part B + 100 parts of water
Example: 10 cc A + 20 cc B + 1000 cc of water make approximately one litre working solution (1030cc). Measure the quantity of water and add the A and B stock solutions. It does not matter which is added first.
Note: When the PMK working solution is mixed together, it will immediately proceed through colour changes from grey-green to pale amber. This is an important visual check of solution activity. If there is no colour change, something is wrong! Recheck stock solutions for correct formulation and the working solution for correct dilution.