Inconsistency from Session to Session

[Stan. L-B]

Good point Andre'

It is an established fact that CHLORINE reduces the strength of many chemicals, particularly those used for photographic purposes. Here in the UK, particularly London,
it is put into our drinking water whether we like it or not. But teeth are said to last longer with it!

 

[Foto Ludens]

Good point Andre'

It is an established fact that CHLORINE reduces the strength of many chemicals, particularly those used for photographic purposes. Here in the UK, particularly London,
it is put into our drinking water whether we like it or not. But teeth are said to last longer with it!

Yup, Chlorine (the swimming pool stuff) and fluoride are commonly found in the drinking water of developed nations. The U.S. has this too, and regardless of nation, minerals are found in the water, though to different degrees. I think that North Texas, where I live, has pretty hard water (that is, high in minerals). This is noticeable when I develop film. The diafine (distilled water) is mild in color, but the water stop that comes after it (tap water) becomes dark in color within a few minutes of leaving the tank. Really amusing when you've done nothing but develop film all day.

Alright, enough typing for now, I gotta go deliver some pizzas (new job).

 

[gainer]

Heart attacks are fewer in areas of hard water, unless you count those caused by stress due to problems with developer.

Chlorine, fluorine and oxygen in water can cause loss of activity in ascorbate developers. Excess sodium ascorbate or sodium erythorbate (aka sodium isoascorbate) can cure it.

I have a Leica M3 with clip-on meter that would probably work. I'm not familiar with your meter. The object is to measure the output of the lamp, which can be done consistently by making the bellows as short as possible, removing the lens or lens board, and placing the meter right at the opening.

 

[geraldatwork]

Gainer,the clip on meter I have was made by Leica (actually for) that couples to the shutter dial. I could probably use that to check the lamp as you suggested. Although since my exposures within a session are consistent I doubt that is the problem. Sometimes to check an exposure I'll leave the darkroom with a wet print and put it in the microwave to simulate dry down. So from the time I exposed the print/developed/fixed/dried/maybe had a snack could be 20-30 minutes. When I make an exposure change whether I'm satisfied with the change or not it usually is consistent. But it is still good to know.

I will however use distilled water to mix the Dektol and then again when I dilute it 1 +2 for the session. I am going to throw out the Dektol I mixed last week and start again since it is cheap enough. I will also certainly be more consistent with the temperature of the developer.

 

[Foto Ludens]

good luck, gerald. let us know how it turns out.

 

[Shesh]

Yeah, let us know. I'm very curious to know what turns out to be the actual cause for the problem.

 

[Deckled Edge]

if it is weeks and even months between sessions i would look at the way you are storing the developer. oxidation will occur if not carefully capped.

You can check the quality of the developer in real time if you use this rule of thumb: Dektol @1:2 begins to produce mid-tones in 30 to 35 seconds. Develop exactly 4x the time it takes to see mid-tones. This will compensate for oxidation, temperature variation, sun spots and hangovers.

Tip 2: Stop down one stop on the enlarger lens and double the exposure time. This will increase accuracy and eliminate some effects of current fluctuation, bulb warm-up time and dodge-burn spasticity.