While working with the testing of several developers I came to the conclusion that TCB and PCB developers have good shelf-life, but when used and re-used as D76, they became less active rather quickly. This because the ascorbic acid is destroyed by arial oxidation during use.
To overcome this problem I added some sodium sulfite to the TCB developer.
The tests shows that this fortified TCB developer doesn't loose it's breath so quickly. In fact it closely follows other reuseable developers. For a 1000ml stock bottle, add 6% of the developing time for each film developed.
Use the same table as shown in the article about the Fenomenal developer.
You will need Parodinal to make this. The mixing instructons are outlined here.
Making p-aminophenol from Tylenol/Paracetamol with ascorbic acid as anitoxydant doesn't work as good as doing it the proper way.
500 ml water.
8 g Soduim carbonate. (Soda)
10 g Ascorbic acid. pH at this moment is 9.6
80 g Sodium sulfite
10 ml Parodinal
20 g borax.
Water to 1000 ml. pH at this moment is 9.15
Starting time: 10 min @ 20C for Fomapan 100
This triplet is exposed +-0EV, -1EV and +1EV.
This is the image exposed according to the meter. Contrast increased a bit.
Sharpness is good. Grains are fairly small.
These images was extracted from the 4.th film through a 500ml batch of the developer.
Development time was 14 minutes @20C. This complies with the table for increasing time for each film. Since this is a 500ml batch, the starting time is multiplied with 1.42, giving me 14.2 minutes. The correct time is 14 minutes and 12 seconds, but the 12 seconds isn't going to make any visible difference at 14 minutes, so let us forget about them.
I am going to put this stock bottle on the shelf for now. Sometime i February or March 2012 I am going to develop a film or two in it to make sure it can survive some weeks on the shelf.
I am quite sure it still will be active by then.