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Showing posts with label mix. Show all posts
Showing posts with label mix. Show all posts

Saturday 30 June 2012

Adox in PMK Pyro results.

Test stips at twenty and ten
Minutes

The results are in! This has turned out to be one of the most exasperating tests to date. There have been problems all along the way from getting the exposures right to developing the film. Having said that there have been some surprises.

As with the Agfa test the film was exposed at box speed ISO 100 in the Nikon F5. This is where the process changes apart from the test method. The PMK Pyro used was one I made from raw material that did not include EDTA disodium in the mix and a reduced amount of Sodium Metaborate in solution B.

Sequence of development:

         Pre-soak - it makes no difference with this film. It is not prone to air bell/bubbles sticking to the film.
         Developer - to be made up immediately before use at 21 degrees C.
         Development times - for this test were 5, 10, and 20 minutes respectively.
         Tank inversions - continuously for the first minute and then once every fifteen seconds.
         Stop, Fix and wash - as normal.
         After bath - was not used and would have made little difference with this mix.
Notes:
Adox CHS 100 PET 35mm is not like other black and white film it has a noticeable thinner film base which is coloured blue. The cassette this film came in was not light tight which almost ruined the test. I only discovered this after the film had been exposed, when removing the film from the cassette it fell to bits. I have read a forum thread saying that the 120 roll film has the same problem. Adox you need to up your game! It is appalling quality control.


Pre-soak water after use
If you use a pre-soak the water will come out blue.


The ten minute development time is the one suggested by Digital truth, which made it the reference time the other test strips were to be judged against.





Results
All the test strips including the one thats a no show.
The test strip to show the best density of negative is the twenty minute one, having said that they are still a bit on the thin side. This does not take away from the fact that they are fully toned and well defined. There is no sign of grain when enlarged to 485 mm (19”) by 340 mm (13.5”). When printing the negatives I'm having to use grade three, normally I would expect to be using grade two, this could be due to the lack of EDTA in the mix of Pyro used. I'm also disappointed that the five minute test strip shows no negatives at all, from previous experience the shorter/half development times have a faint out line. In this case I can only put it down to the faulty film cassette. The ten minute test strip is very thin when compared to the Agfa test strips it is thinner than the half development time. Which suggests that normal development in this case should be greater than twenty minutes.

Over sized enlargment


With all the time and effort put into this test the last thing I was expecting was to be let down by bad manufacture. Of the thirty six exposures on the film around about  ten frames are unaffected by some light damage luckily the majority of these are from the test exposures that put in an appearance. If there was going to be any question marks I was thinking it would be from the developer but it did not disappoint, the only thing to note was when i poured it from the developing tank it was a lovely pink rose colour.

Will I be using the film again? Yes! only because I have a roll of 120 on the shelf if the negatives show any light damage then I will not use it again. How can I say that when I use a lot of out of date film? With out of date film at least you know that the results could be iffy. You don't expect it from new in date stock.
Used PMK Pyro.

Friday 9 December 2011

Farmers reducer.


This is a follow on from my last post on reduction.

Over developed or over exposed negatives may need to be reduced to make them a better printing prospect. This is achieved with chemicals that strip silver from the final image. Like developing, reducing a negative requires practice so you get an idea of how much to take away. It is best carried out in a place that is well ventilated with diffused light so you can see the process at work. It is a good idea to pre-soak the film it will allow you more control by slowing the process down. With experience you will get to know at what point to remove the negative. The chemicals do not stop working instantaneously. Because you can repeat this procedure it is better to reduce the negative in small steps so as not to over do it.

Reducers can be supplied ready mixed or you can mix your own. The formula that follows is a proportional reducer for overdeveloped negatives:

Stock Solution A

  • Potassium Ferricyanide 7.5 grams.
  • Water 1 litre.

Stock Solution B

  • Sodium thiosulphate (Hypo crystals) 200 grams.
  • Water 1 litre.

Notes: Ferricyanide has good keeping qualitys if kept out of strong sun light. Once you have mixed the chemicals you should use immediately. If you are using a stepped method of reduction do not contaminate solution A with Solution B as it will stop working. Working temperature of 20 degrees. You can place a dry negative in solution A but will need to watch the process carefully for between 1-4 minutes then transfer to solution B for about 5 minutes.

Potassium ferricyanide is a poison. Avoid contact with your skin and do not breathe the fumes.