Sw reversal development With Foma kit

Gast · 2005-05-27T08:45:49+00:00

Hallo, wie exakt muss man es bei der SW-Umkehrentwicklung mit den Temperaturen der Bänder halten? Bei der SW-Negativentwicklung stecken die klassischen SW-F...

Gast

Hello, How precisely do you need to maintain the temperatures of the strips when using the SW reverse process? With the SW negative process, classic SW films such as Ilford FP4 and HP5, Agfa APX 100 and APX 400, and Kodak Plus X and Tri-X can easily cope with fluctuations of a few degrees Celsius. Is it similar with Foma 100 R in black-and-white reversal processing, or do you have to be extremely careful to stick strictly to the specified processing temperatures? If so, how do you manage that without a processor in a makeshift kitchen or bathroom darkroom? I’d be grateful for any tips. Best regards, Fred

mau

You determine the tolerances for the design parameters based on your quality requirements, and the more unusual the material, the tighter the tolerances.

cfb_de

Hi Fred, It’s all in the Hilgert/Rohleder book, actually. It’s even explained in a way that I’ve managed to understand it. Best regards, Franz

Gast

@ cfb_de Unfortunately, Hilgert and Rohlder say absolutely nothing about the very point I’m asking about. They carried out the reverse process in a Jobo processor, which maintains a constant jacket temperature. I don’t have one of those and I don’t want to buy one either. That’s why I asked about the permissible temperature tolerances... Regards, Fred

cfb_de

Hi Fred, You’re absolutely right :-) Off the top of my head, I reckon maintaining a constant temperature is just as important as it is with standard negative development. It should work even in a can without a processor; after all, it works with C41 and a bucket of water. With 20°C processes, you don’t even need a bucket of water; the temperature inside the can hardly changes at all. Temperature is only critical during the initial development anyway; bleaching is done by eye, the second development is carried through to the end, and fixing is as usual. Best regards, Franz

MirkoBoeddecker

Fred, I wouldn’t deviate by “a few degrees” even with “normal” development. Plus or minus one degree is within the range of what’s possible without the results varying significantly. As far as temperature tolerance is concerned, the reversal process is basically a “perfectly normal” black-and-white process. So you don’t need to work with an accuracy of +/- 0.5 degrees, as you would in the colour process. The first and second developers are “normal” black-and-white developers and are responsible for the grey tones and contrast just as they would be “otherwise”. The remaining factors have little influence on the contrast or grey tones, so temperature fluctuations aren’t that important. The main thing is that the Bleach bath bleaches sufficiently and the stop bath (or exposure) is also “sufficient” or adequate. Errors in the reversal process are less about temperature fluctuations and more about: 1) Preparing the Bleach bath too early and letting it go off before it is used 2) Reusing the Bleach bath 3) Insufficient or uneven second exposure 4) Rinsing for too short a time 5) Rinsing with water at 2°C and filling with developer at 20°C.... 6) etc. Best regards, Mirko

Gast

Thanks for the tips. If the SW reversal process is comparable to the SW negative process in terms of the required temperature accuracy, I might just give it a go in my makeshift kitchen lab... Best regards, Fred

camerafreak

@ cfb_de Unfortunately, Hilgert/Rohlder say absolutely nothing about my specific question. They carried out the reversal process in a Jobo processor, which maintains a constant jacket temperature. I don’t have one of those and don’t intend to buy one either. That’s why I asked about the permissible temperature tolerances... Regards, Fred

Hello Fred, Densitometrically, temperature deviations can also be detected in a standard SW process; a difference of 1–2 degrees is certainly sufficient. We used to take 24°C as the reference temperature because I’ve standardised all black-and-white processes here to 24°C, purely for practical reasons: here in my lab (i.e. before the air conditioning was installed ;-)) temperatures are usually above 20°C, and ventilating to keep it warm is usually technically easier to achieve than constantly cooling it. Why don’t you use a water bath? A simple plastic container from the supermarket and an aquarium heater, and your ‘inversion processor’ is ready. The temperature stability of these heaters is very good. For temperature control of chemicals and for storing the container between inversion intervals, this setup is accurate enough; some people even run their E6 processes this way... if temperatures get too high, you simply add a cooling pack. Regards, Michael H.

Gast

Hi Michael, That's a good tip about the aquarium heater. I'll give it a go, thanks. Regards, Fred