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.
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. |
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.
