Need help with Xtol mixture

I have been helping out in a darkroom and I have inherited an unusual way to mix 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.

Welcome to APUG.
Is the resulting total volume two US gallons? If so your resulting total volume is about 7.57 litres or, as you say, about 1.5 times the "standard.

If I were you I would chart out three data points for each film you currently have "favourite" times for: your times, Kodak's recommended time for development in "stock" and Kodak's recommended time for development in 1+1. From that data, you may be able to interpolate where your favourite times fit between the Kodak times, and derive from that a rule that can be applied to other films.

For example, if your favourite times for the listed films are halfway between the two Kodak recommended times, you've got your rule.

Thanks for the welcome and the suggestion. I will have to try that. The chart we have seems to work well, but when I tried to develop some Neopan Acros 100 both the stock and the 1:1 times seemed to give me thin negatives. I could still make prints, but it was a bit challenging. I want to see if the director of the darkroom will let me make some "stock" and see what if any difference that makes. Anyway thanks again.

I'd be inclined to use Kodak's instructions instead, then you have what Kodak intended as a stock solution. From this you can use stock solutions or 1+1 according to Kodak's times for a long list of films.

Why complicate matters?

pentaxuser

pentaxuser said:

I'd be inclined to use Kodak's instructions instead, then you have what Kodak intended as a stock solution. From this you can use stock solutions or 1+1 according to Kodak's times for a long list of films.

Why complicate matters?

pentaxuser

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TIMES 10,000! [by ! I mean factorial]

First of all Kodak knows more about their product than we ever will. Second, if you have a problem, we cannot help you because we have no experience in your darkroom's XTOL use. Third, I have used replenished XTOL for many years and never had a problem. Therefore, others and I can help you with replenished XTOL. Fourth welcome to APUG.

Sirius Glass said:

TIMES 10,000! [by ! I mean factorial]

First of all Kodak knows more about their product than we ever will. Second, if you have a problem, we cannot help you because we have no experience in your darkroom's XTOL use. Third, I have used replenished XTOL for many years and never had a problem. Therefore, others and I can help you with replenished XTOL. Fourth welcome to APUG.

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+1

Stick with Kodak's recommendations to avoid problems. As said we cannot help if you devolve into some other method.

You seem to be creating your own problem, do it the Kodak way I can't understand why you wouldn't.

ERG4Life said:

Thanks for the welcome and the suggestion. I will have to try that. The chart we have seems to work well, but when I tried to develop some Neopan Acros 100 both the stock and the 1:1 times seemed to give me thin negatives. I could still make prints, but it was a bit challenging. I want to see if the director of the darkroom will let me make some "stock" and see what if any difference that makes. Anyway thanks again.

Click to expand...

There aren't any laws against odd dilutions and finding your personal time is suggested right in the directions (which your darkroom managers have done) so I don't really see a problem.

The mix you have available to you is not overly dilute so I'd suggest you use it as is; you have other controls, just increase time and agitation to fix your problem.

The reasons they may have started using that mix may be as simple as "we wanted to use gallon jugs, Xtol is easier to dissolve with a bit more water, we normally dilute it a bit for process anyways, and we use it up fast enough that were not worried about it going bad because of the extra dilution." All those reasons are valid.

There is a lot of information here and elsewhere on how to systematically test developer times and film speed. I've always stayed pretty close to the manufacturer recommendations, and that has worked pretty well for me, in general, for many years.
But, as Mark says, there is nothing wrong in striking out on your own and becoming a test pilot.

If your Acros negs are thin compared to other films, you may have more of an exposure problem than a developer problem. I don't see Acros 100 in Kodak's chart, Fuji may have it though. If not, then it might be best to shoot a couple of test rolls to determine the actual speed, then the best developing time. Keep in mind that shadow rendition comes from exposure and highlights from developing time. Most people find that Xtol produces negatives very close to the box speed, I've certainly found this to be true for Kodak films, but it may not be the case for everything.

bdial said:

If your Acros negs are thin compared to other films, you may have more of an exposure problem than a developer problem. I don't see Acros 100 in Kodak's chart, Fuji may have it though. If not, then it might be best to shoot a couple of test rolls to determine the actual speed, then the best developing time. Keep in mind that shadow rendition comes from exposure and highlights from developing time. Most people find that Xtol produces negatives very close to the box speed, I've certainly found this to be true for Kodak films, but it may not be the case for everything.

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Fuji gives eight minutes at stock at 68F. Acros/XTOL is also a regular combination of mine. I develop it at 1+1 under constant agitation for about eight minutes. I agree -- up the exposure if the images are thin. Acros can handle it.