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EcoPro film developer ratios


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I have been helping out in a darkroom and I have inherited an unusual way to mix EcoPro (Xtol) and no one knows why we mix it the way we do. Here is how we mix it, first we dissolve part "A" in one gallon of warm water, then we add another gallon and dissolve part "B." This of course does not equal a 1+0 or 1+1 ratio. We also have what appears to be an in house developing time chart. Here are some examples of developing times (these times are figured on 20 degree Celsius):

Delta 100 - 11:30

Delta 400 - 11:30

HP5 - 10:00

TriX - 8:30

Tmax400 - 10:00

 

We generally get good results with these times, but whenever I try to use a film we don't have on this chart I generally don't get good results. So, my question is does anyone have an idea as to why we might have this ratio or just what the ratio might be considered? It seems to be 1+0.5, but no one has any kind reference chart for that ratio. My concern is that if I go to a stock formula or to 1+1 I will have to come up with a whole new chart and I am not really sure how to do that. Anyway thanks in advance for any feedback

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Dave, I found some information here:

 

Eco Pro LegacyPro Ascorbic Acid Powder Black/ White Film 747716

 

Part A must be fully dissolved before adding part B so I suppose that's why they use warm water with part A.

 

It says it can be used full strength or diluted 1:1 From what I understand diluted developer is more economical and can result in longer develop times and hence less chance of incorrect timing. It increases sharpness but with more grain.

 

I am not sure why they are using 1 + 1/2 dilution ratios. There is an app called massive dev chart you can use. The times for Xtol are evidently the same as the times for EcoPro according to the site below.

 

Digitaltruth Photo - Film Photography, Darkroom Supplies & Resources

 

B&W Film Developing Times | The Massive Dev Chart

 

Kind regards

Chris

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Maybe the ~7.5 litre / 2 US gallon quantity suits your deep tank or roller processor capacity? Or maybe it represents the best compromise between economy and keeping properties for your average film turnover.

 

Whatever; the dilution is indeed near enough to 1.5 x stock. Therefore I imagine that using a time midway between those given for stock and 1+1 diluted would be close to ideal. Certainly close enough for commercial processing purposes.

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