Could XTOL be mixed as a concentrate?

[Rob-F]

Just occurred to me. Would XTOL dissolve correctly and completely in less than five liters? And then diluted for use? It might help to keep it on hand for a longer shelf life. Would it dissolve completely at 2.5 liters, double strength? Could it be made even more concentrated? What if we could mix it as a 1 liter concentrate, to be diluted 1:4 for full strength, and 1:9 for a one-shot?

I know we have some chemists here . . .

 

[venchka]

I haven't mixed a lot of Xtol, but I seem to remember it taking some doing to get it all dissolved.
Give it a try and let us know. You won't waste the powder. Just keep adding water until you get it dissolved.
This is a good idea. I like Xtol.
In the meantime, HC110, Rodinal, Pyrocat HD and other developers come ready to do what you are seeking.
Wayne

 

[john_s]

I have mixed Xtol as double strength. It takes some dissolving. I have used water a tiny bit warmer than specified. Make sure Part_A dissolves completely before adding Part_B.
I have done this to make storage easier and it probably makes it more stable. I put it in Schott 250mL bottles to the 250mL mark, then top up with a tiny bit extra water to exclude air. So the bottle then contains about 300mL, then for use I make it up to 500mL.

 

[Freakscene]

I got a 5L pack to dissolve into 3L - when I did it into 2.5 I needed to heat it too much and lost some activity (measured at ~3%).

Xtol Provides great base speed but was always slightly disappointing as a true push developer because it exhausts too quickly. I did some experiments with concentrated Xtol as a push developer but was forced by circumstances to stop before I could draw any firm conclusions.

Marty

 

[Rob-F]

I got a 5L pack to dissolve into 3L - when I did it into 2.5 I needed to heat it too much and lost some activity (measured at ~3%).

Xtol Provides great base speed but was always slightly disappointing as a true push developer because it exhausted too quickly. I did some experiments with concentrated Xtol as a push developer but was forced by circumstances to stop before I could draw any firm conclusions.

Marty

Exhausted too quickly--were you using 16oz of 1:1 for 80 square inches? Or using the stock solution? I can't remember if I tried pushing with XTOL. I've used mostly DD-X, TMax, or Microphen. So if you were using 16oz per 80 square inches, and it wasn't good, I will make a note not to push with Xtol!

 

[foto_mike]

Xtol is crazy cheap. Stored properly (I use new 5L wine in a box bags) it will easily last six months. So what if you don't use it all up in six months? Mix another batch. You'll spend $20/year on Xtol that way.

 

[Freakscene]

Exhausted too quickly--were you using 16oz of 1:1 for 80 square inches? Or using the stock solution? I can't remember if I tried pushing with XTOL. I've used mostly DD-X, TMax, or Microphen. So if you were using 16oz per 80 square inches, and it wasn't good, I will make a note not to push with Xtol!

It was stock Xtol I experimented with, and I used 500 mL per roll. For pushing I always found TMax/TMax RS, DDX or Microphen better.

Xtol's development chemistry is complicated and, at least according to the Kodak engineers who invented and commercialised it, not fully understood. The by-products of ascorbate development are inhibitors, which can be handy for preventing blown highlights, but might also slow push development.

For me it's still the best general purpose developer, not that I ve shot much film lately.

Marty

 

[Rob-F]

It was stock Xtol I experimented with, and I used 500 mL per roll. For pushing I always found TMax/TMax RS, DDX or Microphen better.

Xtol's development chemistry is complicated and, at least according to the Kodak engineers who invented and commercialised it, not fully understood. The by-products of ascorbate development are inhibitors, which can be handy for preventing blown highlights, but might also slow push development.

For me it's still the best general purpose developer, not that I ve shot much film lately.

Marty

Very interesting! Especially interesting: "according to the Kodak engineers who invented and commercialised it, not fully understood."

That would be Sylvia Zawadski (just happen to know). I think of her as a chemist and inventor. Is she a chemical engineer? She's invented various things for Kodak.

It's fascinating that people can develop things without quite understanding them. It even applies to medicines. In a typical description of an antidepressant in the PDR, it will say, "The mechanism of action is not understood."

Chemists are among the smartest people, I believe. I know someone who invented one of the neuropsychiatric medicines doctors prescribe. She gets an idea, gets up at 3AM, works out on the elliptical, and drives to the lab and gets started.

 

[MikeL]

Exhausted too quickly--were you using 16oz of 1:1 for 80 square inches? Or using the stock solution? I can't remember if I tried pushing with XTOL. I've used mostly DD-X, TMax, or Microphen. So if you were using 16oz per 80 square inches, and it wasn't good, I will make a note not to push with Xtol!

I've been happpy pushing with XTOL, but at stock.
Some old stuff- http://www.rangefinderforum.com/forums/showthread.php?t=116789

 

[Freakscene]

Very interesting! Especially interesting: "according to the Kodak engineers who invented and commercialised it, not fully understood."

That would be Sylvia Zawadski (just happen to know). I think of her as a chemist and inventor. Is she a chemical engineer? She's invented various things for Kodak.

indeed, it was Sylvia Zawadski and Dick Dickerson who invented Xtol for Kodak. Some of it is described in "The Genesis of Xtol" (Photo Techniques Magazine, Vol. 20, No. 5, 1999, p. 62) - the magazine doesn't exist anymore but you might be able to find a copy on eBay or in a library. I'm not sure what Ms Zawadski's background is, but she sure knew her photochemistry when I met her.

It's fascinating that people can develop things without quite understanding them. It even applies to medicines. In a typical description of an antidepressant in the PDR, it will say, "The mechanism of action is not understood."

A lot of science is achieved by observation rather than theory - sometimes it doesn't matter why something works if it does work. I don't personally agree with this approach for medicines (too much scope for unintended effects, including later on, for my liking) but there isn't much long term risk with a film developer. Cost is also a substantial issue - the tools to understand how Xtol develops silver exist, but if a formulation works reliably, why spend the funds to figure out why? For an antidepressant, well, I think that understanding the mechanism should be a compulsory component of registration, but I am not a human medicines regulator, and neither have I ever needed any medication to modify my neurotransmitters.

Chemists are among the smartest people, I believe. I know someone who invented one of the neuropsychiatric medicines doctors prescribe. She gets an idea, gets up at 3AM, works out on the elliptical, and drives to the lab and gets started.

There are smart people in all fields. Your friend sounds creative and driven, which is necessary for what she does. Creativity in general is underrated as a scientific tool.

Getting back to Xtol, its ordinary performance as a push developer (as opposed to providing high base speed) probably has the same cause as dilute Xtol not working well with Kodak TMX, particularly if less than 100 mL of stock is used per film. The development reaction slows too quickly for a good push or to get proper density in heavily exposed (as occurs in high key scenes) TMX.

Marty

 

[Rob-F]

I'm glad I ran across this thread one year later. It's reminding me to not think of XTOL as a push developer, even though it is a speed-increase developer--which is not quite the same thing!

 

[Freakscene]

Thanks Rob-F, this reminded me to report that although not exactly the same, Moersch Eco Film Developer (EFD) contains ascorbates and produces results much like Xtol. You buy 2 bottles, 500 mL and 250 mL and use it 2+1+50 water, so it's very like an off the shelf concentrated Xtol. The lowest amount of stock you can use per film is 10 + 5 mL, at which concentration it works very much like dilute Xtol.

Marty

 

[Rob-F]

That sounds like something I need to do! Where do you get it?

 

[Freakscene]

That sounds like something I need to do! Where do you get it?

I got it here: http://www.moersch-photochemie.de/content/shop/negativ/128/eco_film_developer but I am also in Australia.

Freestyle carries Moersch products but not the EFD, although they carry the Eco Paper Developer. Maybe you could ask them or ask Moersch if anyone is keeping it in stock the USA.

Marty

Edit: Fotoimpex and Macodirect carry Eco Film Developer.