accelerator added to MQ

[Gerald C Koch]

CHQ was used in several commercial fine grain developers. This has to do with its redox potential as compared to other developing agents such a metol. BTW it was used in warm tone developers because of the silver particle size it yields which makes the image appear warm.

 

[Photo Engineer]

My post #24 now no longer makes sense due to the deletions of posts.

Regrets.

PE

 

[timmct]

I have received a number of ALERTS through the administrators of this site.

This is a bit embarrassing and I will try to sort this out.

My apologies to everyone, Tim.

 

[Photo Engineer]

Oh, I got them too Tim.

I don't think apologies are needed.

PE

 

[Ian Grant]

Very starnge, there was nothing even remotely contentious.

I found Tim's comments about his early days mixing Sprint chemistry very interesting, it reminds me of conversations I had with a swenoir Ilford research chemist over 30 years ago and his remarks about mixing Paterson chemistry. Geoffrey Crawley was the chemist behind Patersons B&W chemistry and in the early days they were made for the company by Ilford, they (Ilford) were bemused buy many of the compositions and the un-neccesary components.

Ian

 

[Photo Engineer]

I guess Sprint took this discussion seriously!

 

[David A. Goldfarb]

My post #24 now no longer makes sense due to the deletions of posts.

Regrets.

PE

Sorry to have to remove the context, but the post does leave a way to have the general discussion without necessarily referring to any formulas or practices that may be proprietary.

 

[timmct]

I will, probably, have to ask Sprint Systems of Photography, or their legal representatives, what claims they may feel they may have on me if I continue posting on this site.

The members of this site have my apologies, in advance, for any inconvenience I may have caused or might possibly cause in the near future.

 

[Photo Engineer]

Kodak has not bothered me, and most NDAs do not extend beyond a certain set time limit. In addition, if your prior work restricts future work due to narrowness of field then you are exempt.

IDK what APUG is subject to.

PE

 

[David A. Goldfarb]

APUG members are certainly interested in this information, if the company is willling to share it. Perhaps Tim can legally reveal this information or perhaps not, but at the same time, we'd like not to see the analogue community become divided in bitter legal disputes, even if APUG is not exposed (so to speak).

If we can stick to information that's more clearly in the public domain, that's a way of discussing the question without Tim or APUG getting into questionable territory. And after all, Sprint supplies chemistry to many educational photography programs, and we want them to continue doing that and to do it successfully to promote analogue photography among the next generation of students. I think they're folks we want on our side.

 

[timmct]

When I was engaged to work for Sprint there were no non-disclosure agreements or non-compete agreements offered as conditions for employees.

I'm pretty sure I ceased to be an employee of Sprint well over ten years ago. Thinking on it a bit...probably fifteen years ago!

I'm not sure what the current policies are.

I was actively encouraged to learn as much as I could about all aspects of photography by the principals of Sprint while I was employed there.

 

[Gerald C Koch]

Here is the MSDS for Edwal FG-7. My guess is that the quinone and HCl are reacted first and then the sodium hydroxide added afterwards to neutratize any excess acid. Then the remaining ingredients would be added. Like PE is could never get an equation between quinone and HCl to balance. I assume that Edwal gets something but what is it?

http://www.freestylephoto.biz/pdf/msds/edwal/Edwal_FG_7.pdf

 

[Photo Engineer]

My guess is that it might be mostly or all Hydroquinone Monosulfonate. Or, a broad mix of ingredients, unknown and unknowable. It would depend on temperature, order of addition and concentration. Benzoquinone is only sparingly soluble in water and has a strong odor. With HQ, it forms quinhydrone which is bright green. For the oldies out there, think of Quink green ink.

PE

 

[timmct]

I would have to go with PE on the difficulty of securing CHQ as a pure product, based on process, it can't be easy to make and small variations in the synthesis might lead to disappointing variations in purity.

Some form of this seems to be available...

http://www.sigmaaldrich.com/catalog/product/aldrich/224081?lang=en&region=US

There have been firms that contract this product, from Indian manufacturers, that have been disappointed.

 

[Photo Engineer]

And that one at S-A is only 85% pure, showing how typical the problem is.

PE

 

[timmct]

My own experience with CHQ is that one must accept this chemical with a C of A but, then, conduct tests to verify what the new product might mean in a standard formula.

I had a customer who shot 4 x5 negs as duos in a carrier...developed one to normal standards and the other to his printable ideals based on the previous effort.

He sorted me out with a problem I had with CHQ...Thanks Adolph!

I had to figure on 39lbs.@92% and 41.6lbs.@80% in a batch..

The corollary, here, is that ANY chemical might might come in with a "C of A" and not measure up.

Buyer beware.

 

[Photo Engineer]

I'm sure there must be alternatives.

 

[Gerald C Koch]

Bromohydroquinone which has similar properties is available from S-A in 97% purity. Back when CHQ was in use bromohydroquinone was also popular.

 

[Photo Engineer]

Jerry, I've gone back to the '40s and find just two references to Cl-HQ. It is advertised as a paper developer for red to brown tones. There are 3 or 4 proprietary developing agents that I cannot identify yet. I did find two replacements for Cl-HQ that might be suitable. Sprint! Are you listening?

PE

 

[Ian Grant]

It doesn't help that Kodak had two names for some developing agents like Athenon and Kodurol for Glycin. The older Focal Encylopedia of Photography are usually quite good for checking proprietary names alsoClerc.

Ian

 

[Alan Johnson]

LFA Mason, Photographic Processing Chemistry p142:
By careful choice of ingredients, a highly concentrated liquid may be obtained which is stable at low temperatures.
The use of phenidone/hydroquinone systems enables higher developing agent concentrations to be used than would be possible with the metol/hydroquinone system.Substitution of part of the hydroquinone by chlorhydroquinone enables this to be still further increased.

 

[RauschenOderKorn]

Bromohydroquinone which has similar properties is available from S-A in 97% purity. Back when CHQ was in use bromohydroquinone was also popular.

I am not so sure about the similar properties. I have found some literature stating this, but it seemed like all the authors copied old data from other books.

It is correct that the Ilford Formulae 3rd Edition gives (in the ID-24 recipe) Adurol and CHQ as two possible ingredients which might be interchanged. Adurol, as it seems, has been used for both, BHQ (Schering) and CHQ (Hauff) (source: Edmund Lowe in "What you want to know about Developers - Fine grain and Otherwise" (Chicago 1939) - I got the really lousy reprint "Made in India" from amazon)

Lowe is the only author where I have been able to find more information on BHQ / CHQ other than the very basics given by Eder. According to Lowe the substances show at least one significant difference:

CHQ
Reduction Potential: 7 - Mol. Wt. 144,5

BHQ
Reduction Potential: 21 - Mol. Wt. 189

So this suggests that the two substances will show different behavior of some kind.

 

[RauschenOderKorn]

And that one at S-A is only 85% pure, showing how typical the problem is.

PE

I tried to buy it from them, they will not sell it to private persons in the EU and if they sell to companies, they want to know exactly what you are doing with it. I quote: "Research & Development is not an acceptable answer".

Way to go S-A, one "Happy Customer" more!

 

[Photo Engineer]

Well, in some cases the answer would reveal trade secrets. That is why Kodak inevitably made their own chemistry.

PE

 

[RauschenOderKorn]

Jerry, I've gone back to the '40s and find just two references to Cl-HQ. It is advertised as a paper developer for red to brown tones.

It was also used as a plate / film developer, CHQ being the only developing agent (or whatever the companies had synthesized believing it was CHQ).
Check out the Lowe book, there you can find some more data.