Making up PMK Pyro from Raw.

This is the first time I've mixed a developer from scratch. I find when  preparing for something that is new, it seems to take an inordinately long time to set up. This has been no different and I can understand why more people do not mix for themselves.

Before you start.

If you have just purchased new scales it is a good idea to check how accurate they are. First thing to do is place the scales where you plan to make up the mix and zero them.The table that follows is a simple and affective way of checking the accuracy.

These weights came from the royal mint:

Coin test

        ●         1p – 3.56 grams.

●         2p – 7.12 grams.

●         5p – 3.25 grams.

●         10p – 6.5 grams.

●         20p – 3.0 grams.

●         50p – 8.0 grams.

●         £1 – 9.5 grams.

●         £2 – 12 grams.

An alternative to using scales is the Twenty P mix. This is where twenty p coins are used as a counter balance to weighing out the powders. While talking about alternative ways of measuring out you can use measuring spoons. This could be a more reliable way of ensuring that each mix is consistent. If you measure out the chemicals with number of spoons it will not matter that the powders have changed in volume by absorbing moisture or drying out.

With the checks out of the way what next? How much are you going to make up as stock solution? I know from previous use that it will keep for a very long time, even years. I personally prefer only to have small amounts of developer on the shelf ready for use. This is partly because I use several different film and paper developers.  Anchells Darkroom Cookbook  suggests that you make up part A at 750 mls and part B at 1400 mls; well that is a large amount for a first mix not only that what happens if you get it wrong  or heaven forbid it does not work. Luckily Trevor Crone has published the weights for a smaller amount:

Solution A to make 250mls:

●         Metol 2.5 grams

●         Sodium metabisulphite 5.0 grams.

●         Pyrogallol 25.0 grams.

Solution B to make 500mls

●         Sodium Metaborate 125 grams.

Stock solution should be made up with distilled/de ionised water. EDTA-disodium is an optional ingredient It adds gold tone to the silver of the film.

Trevor suggests a reduction of 10 grams for solution B to help combat separation when mixed. He has also said that to his knowledge it has not affected the quality of his negatives.  I can confirm the drop out is reduced but I think this is mainly due to the reduction of powder. Although these quantities are more reasonable  I made my batch up at half these weights.

Other bits

Paper cup cake holders are a good idea for pouring the powders into when it comes to measuring out but they will only cope safely with small weights. You can get plastic cups to do the job which maybe a better route to take if you plan to mix all your own chemicals.

Common sense should prevail when it comes to measuring out these powders. Gloves and a breathing mask should be the minimum safety precautions taken. If the powder gets air born it will irritate the lining of your nose. Also if you get it on your hands it  will irritate or burn your skin. So please be sensible.  

Adox CHS 100 Pet ISO 100 35mm flim.
Developed in PMK Pyro,
Printed on silverproof paper,
Developed in Ilford warm tone.

Having purchased all the ingredients to mix it myself, is it more cost affective? The over the counter premixed price of PMK is about £9 for 10 litres. The cost of all the ingredients is around £39. The batch that I made up  was equivalent to ten litres and saved about 50p. Taking every thing into account scales, time, safety etc. etc., it may not be worth all the trouble and money as a one off. There are advantages to this method such as the flexibility of making up the quantities of developer, stop and fix you require and being able to try out other developers you would not normal be able to get from the mainstream. The main purpose for me was to ensure a ready supply of PMK Pyro. Now that I have started down this road as my stop,fix and other developers run out they will probably be replaced with powdered formulas.

Acknowledgements and Thanks to the following:

Paul C, for the royal mint weights. 

Mr S. Nichols for the 20 P mix.

Trevor Crone for the reduced PMK Pyro mix.

The Focus finder.

This is a wonderfully simple piece of darkroom equipment. Basicly it is a magnifying glass and mirror. It provides the user with the optimum sharpness for the enlargement by focusing on the grain of the negative. 

Also known as a grain magnifier it rests on the masking frame where it diverts a small amount of light from the projected negative to your eye as you look through the small magnifying lens. With one hand on the focusing control of the enlarger you gently turn the knob until the grain becomes sharp in the mirror. This translates to a sharp image at easel level; to maintain this accuracy a piece of waste photographic paper should be placed in the masking frame with the magnifier on top. It is easiest to focus on the grain with the enlarging lens set at its widest aperture and then re-checked at the working aperture. To make sure that the focus has not changed. 

Some focus finders can only be used in the central area of the projected image. This is because the angle of the light is more severe at the edges and corners. If you wish to check these areas to make sure that the whole negative is in focus you will need a magnifier that allows for this with a wider mirror and tilting aim.