Some Information about B&W Darkroom Work

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Go to other interesting Link Collections  Digital Truth PhotoSource         ( Brilliant collection of themes and links)



Some results about research on the
 

Ilford film washing procedure

The method works, however
 

I recommend to use more water if there are 2 films in a tank.

Download an article (8 Pages) with a detailed report about measurements of film washing kinetics for several film types here and modify your procedure:

Current Version: 1.08 from 08 AUG 06, including now advice for print washing as below.

The article as .pdf file for downloading and reading with Acrobat Reader

There  is an interesting and supporting comment af Marc Torzynski about this paper at another place

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Washing prints:


(Same text is now included in pdf-file above about film washing)

II've been asked frequently what are my recommendations for washing prints?

Here they are:

Fibre paper:
I follow the recommendation of AGFA: a bath of 2% Potassiumcarbonat is used to open the fibres of the paper. Then my prints are washed in a Kaiser tray where the incoming water is guided in a way that the water together with the prints is continuously moved. After some time (10 - 15 min) I catch a print (18x24cm), hold it on one corner, wait until the continuous water stream at the opposite edge turn to droplets, and catch now the water for a potassium permanganate test as depicted in above. In case no colour change is observed a give additional 10 minutes, if colour is changing, I repeat the test every 5 minutes until colour change does not occur. Since I follow this procedure I haven't found any problems with my prints even when they are exposed to daylight for years.

RC-paper:
RC-Paper is too stiff to be washed together with fibre based paper. A few sheets RC paper obstruct the movement in the tray completely.

So I acquired a special RC paper washer: A usual 30 x 40 cm tray, with a tube at the one end, where several small holes distribute water into the tray, and a row of holes in the tray at the other end as water outlet. After a while I found that the amount a water spilled was large, compared with the amount of water used per surface area of a film. And this amount of water should be even less. because the thickness of a RC paper emulsion is much less than of a film emulsion.
 
To check for small water supply (2 l/min) the movement and the distribution of the water in the tray I throwed  some Potassium permanganate crystals into the water. I saw that at these low speed the flow was just at the surface of the water in the tray, but at the bottom, where usually the print are located when washed, practically no water movement occurs. So this tray used as a print washer is badly designed and useless, because it fails completely its task: To provide as much fresh water to the print as possible.

Today, as a conlusion, I wash my RC prints completely separate from the fibre prints. When I start to wash them, each print is individually flushed under running fresh water, which is running quite slow (app. 0.2 - 0.3 l/min) just to remove the water loaded with hypo. Then the prints are collected in a tray with fresh water and stacked one above the other. For this I use a 18 x 24 cm tray with app. 1 l water in. After a while (app 30s)  I start the same procedure, i.e. each sheet is hold individually under slow running fresh water and put into another tray with fresh water. The main principle is to follow what I have found for film washing: reduce the amount of take over as much as possible .

Before I transfer the last sheet into the next tray I examine it with the Potassium permanganate test as depicted above. As long as I can observe a colour change I proceed. When the colour change is no longer visible, I give two additional wash batches. It is astonishing how small the number of batches is: for 20 18x24cm prints usually 4-5 batches are sufficient.

After all, my recommendation is to check the efficiency of washing and control it as described. All other rules (apply exact  times and temperatures,  specific agitation, and what ever...) do not work reliable.

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Do you measure temperatures and believe you measure correctly? Then read the article about temperature measurement:

Thermometers: Unreliable assistants!  

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Bauanleitung für

Präzisionswaage für Entwickleransatz für € 5.-

(Sorry, currently only in German, an instruction how to build a precision scale for weighing chemicals for photograhic purposes (Investment: € 5.- ):
 
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