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.

Pyro PMK Raw what is needed

I have been purchasing PMK Pyro as a set of pre-mixed powders just like ID11 and D76. Two of the most popular mass produced powdered film developers; just add water and away you go. Recently I have needed to replace my stock of PMK developer so went to Silverprint my regular supplier to replenish the stock, only to be told that they no longer did mixed batches for sale over the counter. They advised me they stock all the ingredients for self mixing. This took me aback, several expletives entered my head (which were not expressed) what was I going to do! I have a number of tests planned for developing other makes of film let alone the projects on going.

Raw chemicals to make up PMK Pyro

I raised the question on the film and darkroom forum and after the responses  came back (thank you all) I decided to buy the individual ingredients; it is quite expensive to set up, partly due to the way the powders are sold but should make it cheaper over time. This raised the thought of making up all the chemicals I used in the darkroom from powder, meaning they will be as fresh as possible at the point of use. 

What will you need? To start with a set of scales, they do not have to be that expensive but should be able to read very small amounts. The relevant powdered chemicals which are, Metol, Sodium Bisulphite (Sodium metabisulphite), Pyrogallol, EDTA di-Sodium (optional) and Sodium Metaborate (Kodalk).

PMK Pyro a working solution

I am no stranger to making up developers from powders into stock solutions. The first thing you notice is the very small amount it makes up. Next, it comes in two parts and last, the powder needs to be mixed into distilled/de-ionised water ( used for car battery top ups ).

Solution A mixes up as follows:

Pour 80 mls of de-ionised water at room temperature into a measure. Open the packet marked A inside there are two sachets, take the smaller one and mix that in until it dissolves, do the same with the second one. It is important that they go in, in the right order. Make the solution up to a 1oo mls once done pour into a small storage container.

Solution B

Pour 160 mls of de-ionised water at room temperature into a measure. Add the contents of packet B slowly to the water stirring all the time until dissolved. Then top up to 200 mls. Again pour into small storage container.

Some notes:

By the time all the powders are mixed in, the amount of top up will be very small. The distilled/de-ionised water helps it to stay fresh and will keep well in partly filled bottles. Solution B has a bit of drop out and will need to be shaken clear before use. Makes up to 10 litres of working developer.

Freshly made PMK Pyro

Making up a working solution:

A normal mix is as follows,

•   One part A + two parts B to One hundred part of water.

e.g: To make 600 mls of working developer. Measure out 500 mls of water add 6 mls of solution A then add 12 mls of solution B and top off to 600 mls and stir. It is important that they go in in this order.

Notes:

•   When you add part B to the water it will turn a straw colour, if this happens it's OK to use.

•   Working temperature should be 20- 21 degrees C depending on which make of film you are using. You can check this with Digital truths massive dev chart.

Used PMK Pyro
developer.You reuse this at the
end of the process to add extra
stain to the negatives.

•   Prepare everything else before you make up the working developer then use it straight away as it oxidises very quickly.

•   When you pour the developer out at the end of the allotted time the solution will be very dark brown.

•   It is a 'use once and throw away' developer.

•   It is not necessary to re-dip the film in the developer after it has been fixed to increase staining.

•   Make working solution up with filtered tap water.