Mocon -- XTOL-quality in a long-lasting concentrate

albada · Apr 7, 2013

albada submitted a new resource:

(there was a url link here which no longer exists) - Mocon -- XTOL-quality in a long-lasting concentrate

Mocon is a two-part developer consisting of a long lasting liquid concentrate and sodium sulfite powder used one-shot. It was originally intended to be an XTOL-clone, but it turned out to be not quite that. Mocon generally gives slightly finer grain than XTOL and slightly lower true film-speed. To match XTOL, you can modify Mocon, or try Mocon-X which is also described in this article. Mocon stands for "Mark Overton's Concentrate", and its temporary name was 214D. The goal of this project...

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Rafal Lukawiecki · Apr 8, 2013

Congratulations, Mark, and thank you for doing this work. Without dedication of people like you, our craft would not advance much, anymore, as the big manufactures, sadly, no longer seem to do, or share with the world, any significant photochemical R&D.

Bruce Osgood · Apr 8, 2013

I echo Mark's statement, thanks for the work.

zsas · Apr 11, 2013

Well documented! When I do my next Formulary order I might just get some of these chems to give it a try! Congrats on your accomplishment and for all who contributed! I have to say, the thread where this was beings developed in was a bit over my head, I appreciate you doing such a nice post write up with actual mixing examples! This kind of care in good clear writing goes a long way towards somone like me (weekend darkroom hobbiest) actually trying this!

kb3lms · Apr 11, 2013

Mark, thank you for all the work you have put into this project and the great write-up. I'm still working off my D-316 but will be trying Mocon soon.

Griz · Apr 13, 2013

I've followed this thread from the beginning with great interest, and I'd like to thank everyone that has contributed to the process! While I am NOT a chemist by any stretch of the imagination, I have learned a thing or two along the way, and I appreciate the dedication and hard work that has gone into this project!

Congrats Mark!

Griz

john_s · Apr 16, 2013

Thank you Mark! What a job!

If I have 8-mol sodium metaborate instead of 4-mol, and if I adjust for the molecular weight (x137.88/101.83) would the extra water of crystallization make much of a difference to the longevity of the concentrate? I don't need stupendous life: 6 months would be fine.

Alan Johnson · Apr 16, 2013

John,
I did the D-316 keeping test mentioned here:
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I started this before I knew there were 2 forms of the metaborate, 4-mol and 8-mol,aka Kodalk of which 1.354 times the weight is needed.
The form I used was probably 8-mol Kodalk ,it is not labelled on the old pack but looks like some known Kodalk I bought later.
So 8-mol is probably good for at least a year but I cannot say for sure.

albada · Apr 17, 2013

john_s said:
Thank you Mark! What a job!
If I have 8-mol sodium metaborate instead of 4-mol, and if I adjust for the molecular weight (x137.88/101.83) would the extra water of crystallization make much of a difference to the longevity of the concentrate? I don't need stupendous life: 6 months would be fine.

Hi John,
As Alan just posted, 8-mol will probably last long enough, especially if you keep the concentrate chilled or frozen.
But if you use 8-mol, don't forget to increase the amount of concentrate you pour out when mixing.

Everybody:
Thanks for the kind notes. They're encouraging. Yes, I try to write clearly, even though I'm a software geek by profession.

Mark Overton

Steve Law · Jun 7, 2015

I too, have 8-mol sodium metaborate instead of 4-mol. What do I need to do to compensate for this, if anything?

Steven

StephenT · Nov 20, 2015

WOW! Great work Mark. I think I'll try to mix up a batch.

Jeff S. · Apr 3, 2016

Just tried mixing this yesterday. My first attempt at mixing a developer from bulk chemicals. My question is, my concentrate has an orange tint. Is that to be expected? I got the mixture a little hotter than 75 C for the last ingredient. By the way, I used Phenidone instead of Dimezone S. Will try it today and report back.

Photo Engineer · Apr 3, 2016

Congratulations Mark.

PE

Alan Johnson · Apr 3, 2016

Jeff S. said:
Just tried mixing this yesterday. My first attempt at mixing a developer from bulk chemicals. My question is, my concentrate has an orange tint. Is that to be expected? I got the mixture a little hotter than 75 C for the last ingredient. By the way, I used Phenidone instead of Dimezone S. Will try it today and report back.

The orange color is probably a small amount of diketogulonic acid, formed possibly at higher temperature due to oxidation.
It is unlikely to have any significant effect as the pH mostly depends on the other ingredients.
(there was a url link here which no longer exists)

Mocon -- XTOL-quality in a long-lasting concentrate

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