After many long months I have finally managed to improve on my development method and finally found the time (and effort, had some friends who were interested to help me out with the preparation) to develop a few rolls. The only exception this time, was that I used thiourea to replace the fogging agent, second developer and fixer.
For the benefit of those who are new to this, BW slide developement from normal BW negs follows this process:
- First development - to develop the negative image
- Bleach - to remove the developed negative (leaving the undeveloped positive behind)
- Clearing Bath - to clear up the highly oxidized material on the film
- Second Developer with fogging agent OR re-exposure to light - to expose the undeveloped positive and develop it
- Fixer - to remove any residual silver halide
- Final Rinse
All these has to be carried out below 20 deg C; which is troublesome as it requires a lot of ice and a water bath and constant monitoring. As such, this time round, I used thiourea to replace the 4th and 5th step and most importantly, remove the need for re-exposure to light (this is the one that cause majority of the problems).
Sample photos:
There are some mysterious white spots on the emulsion which I cannot seem to figure out.. Had it only on this roll. I read that it could be due to residual powder from incomplete mixing of powder developer, but I used PQ developer which is a liquid concentrate (maybe the one I used was like half opened for almost a year already), so this is quite puzzling. Any ideas?
100% crop of the second picture. The acutance is rather poor, but on the plus side, the grain is almost invisible.
Photos was shot on Ilford PanF 50, Mamiya 7
FAQ:
Some advantages of using thiourea? Archival images.. Silver sulphide is known to be very stable and no worries about the image decomposing.
Drawbacks? You get sepia toned images.
Where to get thiourea? You can find it in a box of Tetenal Triponal Toner which ruby sells.