Why a monobath?

I have decided that in the interests of space and time regarding my darkroom facilities (read: downstairs half bath) and other constraints that I am going to begin experimenting with HC110 and Kodafix as a monobath for tray processing of 4x5 sheet films. I will be using this chemistry as it what I have on hand, merely convenience at this time.

Materials involved

HC110
Kodafix
Exposed Ilford HP5+ to begin
Tap Water (as long as I can't taste the chlorine, SOP in the Walrath Darkroom)
Total elapsed time from insertion of first sheet until end of rinse - 35:00

Preparation

I will be shooting five identical test exposures with a grey card against a white wall with enough seperation that I can have a five zone difference between the two. I will place the wall on Zone V and the Grey Card on Zone 0. This will provide negatives with a middle density and a portion that has no density (less film base plus fog). When I get to a negative that shows no density in the Grey Card portion of exposure and increased density in the next, I should be on the time and sequence with the first negative.

In preparation, I will prepare one litre of HC110 at a dilution of 1:49 with 20C water. I will henceforth refer to this dilution as Dil J (Thank you, Jason Brunner). I have increased the dilution beyond the 1:31 I was orginally planning to employ based on a recommendation by David Goldfarb, stating that when the fixing agent was added the developer would be more dilute and would cause less interference on the action of the fixer. I will also have 100mL of Kodafix, full strength, at the ready to be added at a later stage.

Process

I will be first developing 4x5 sheets of Ilford HP5+. I have a base time for HP5+ 4x5 sheets with continuous agitation at 20C in HC110 Dil B at 5 minutes. I will be increasing the dilution by a factor of 1.5 so I will increase the time to 7.5 minutes at 20C with continuous agitation.

I will first fill the tray in the light with the one litre volume of HC110 Dil J. I will situate the film and fixer (Kodafix 100mL full strength) in an easy to get position. I will be agitating continuously throughout the tests. To get a range of times in the test I will process seperate negatives together at T+10 and T+20 and at T-10 and T-20. So the actual test time for developing will last nine minutes. I will insert the first sheet, start the timer. At the 45 second mark I will insert the second sheet. At the 1:30 mark I will insert the third. At the 2:15 mark I will insert the fourth. At the 3:00 mark I will add the last sheet. This will give me processing times of 6:00 (T-20), 6:45 (T-10), 7:30 (base), 8:15 (T+10) and 9:00 (T+20) in one single test.

Once the development period of nine minutes has elapsed I will then introduce the 100mL of the fixing agent into the developer. I will continue agutation continuously of course. I will allow the fixer to act on the film for a further 4:00, a total elapsed time of 13:00. I will then inspect the negatives in low light. If the film seems to have cleared I will then fix for a further 3:00.

I will, at that point (16:00), remove the film to a rinsing bath and allow the film to rinse in water for about 20 minutes. I will then inspect the negatives and determine of any of the times are appropriate for further use.

Conclusions will follow . . .

I welcome any discussion and further suggestions and I will post all updates here. Feel free to participate.