Why Pyrol rather than hydroquinone?

[NER]

A citation ... ??

 

[psvensson]

A citation ... ??

If you don't trust any of the excellent people on the board who report getting a stain with hydroquinone, try it yourself. It's very easy and the stain is obvious if you bleach out the silver.

 

[Tom Hoskinson]

The stain effects are are also easily quantifiable with a color densitometer. I have previously published the D Log E comparisons (visual channel vs blue channel).

 

[dancqu]

... the excellent people on the board who report getting
a stain with hydroquinone, try it yourself. It's very easy
and the stain is obvious if you bleach out the silver.

" ... report getting a stain with hydroquinone, ... " on film.
I'd think the very similar character of paper emulsions would
also serve to demonstrate.

I remind myself now and then when testing a paper-developer
combination that paper has in effect a slow speed film emulsion.
I've only a loose connection in mind at present twixt a papers
response and expected performance with film.

To quantify or calibrate I'd have to now and then shoot a roll
of film then process. Less of a job for a sheet film user. Dan

 

[sanking]

The stain effects are are also easily quantifiable with a color densitometer. I have previously published the D Log E comparisons (visual channel vs blue channel).

Just to back up what Tom and Jay have stated hydroquinone is definitely a staining developer in the right formula with low sulphite.

Sandy

 

[NER]

I rely on the scientific literature for authoritative information on photography, not the words of people who talk more than they photograph. Anyone can pretend to be an expert on the internet. I do not. However, I can say that in more than 20 years of study, I have not come across a single description of hydroquinone as a staining developer. Perhaps I am reading the wrong journals. If someone can provide me with a citation to support this declaration, I will look into it. Until then, I regard the claim as unsubstantiated, notwithstanding opinions to the contrary registered here.

 

[psvensson]

Then what are you doing on the forum? Clearly it signifies nothing to you.

 

[NER]

Let's stick with the issue, shall we?

 

[sanking]

Let's stick with the issue, shall we?

So exactly what is the issue? Your ignorance of the literature?

Patrick Gainer published an article in Darkroom Tehcniques some while back (perhaps someone else will note the exact issue number) in which he reported that hydroquinone in low sulphite formulas can be formulated as a staining developer, and he gave a formula that proves his finding.

Since that time many people have experimented with hydroquinone in low sulphite formulas and confirmed Mr. Gainer's findings. Hydroquinone can definitely be formulated as a staining developer.

Sandy King

 

[Mateo]

I'm confused. Do you want people to spend more time making photographs or do you want them to "cite or publish"? This forum, at least for me, is an informal means of discussing personal experience with materials and the atmosphere is one of friendly sharing and even disagreement. Why not share your experiences and even disagree, but keep combatativeness to yourself?

I know that I will probably never try using a staining HQ developer because I am set in my ways with the materials that work for me. Wouldn't it be better for you to try an HQ developer and share your personal findings? That would be a good way to add to the discussion and keep it on topic.

 

[NER]

How disappointing. I insist on a supporting citation because I rely on the scientific literature for factual information, not internet discussion sites, and I am called ignorant and combative! Good luck to all of you.

 

[Canuck]

Hydroquinone is not a staining developer. It exerts a tanning effect, and has been reported to tan (crosslink) more efficiently than pyrogallol or pyrocatechin

Excuse me for asking but my terminology isn't up to snuff. Please explain the difference between tanning and staining.

 

[Canuck]

You're in a hurry. Mr. Canuck wishes to go where no man
has gone before then return and tell us of his findings.

I will suggest he give a bicarbonate-carbonate blend a try;
perhaps a 50/50 blend by weight for starters. Dan

As I get the time, I like to tinker just to see what will happen. Dan, I'll try your suggestion of a 50:50 blend just to see what happens, when I get some free time. Not good this time of year

 

[NER]

NER, you can claim disappointment if you like, but when you presume we "talk more than we photograph", and "pretend to be experts", you don't exactly endear yourself to us. I can say with authority that I know more about staining hydroquinone developers than you do, which isn't much, and certainly doesn't make me an expert. Good luck to you.

Jay

The statement that you know more about this (or any other subject) than I do seems a rather foolish and arrogant boast given that you do not know me at all. Speaking with "authority" is one thing, and speaking with "accuracy" is another. I haven't seen your photographs (I doubt they match your rhetoric), but I have read enough of your harangues to know you desperately want to be recognized as an expert here and around the world. Unfortunately, your last argument with S. King, whose note above is quite revealing, demonstrated that you are not as smart as you think you are: it was riddled with mistakes. So yes, I agree that you are no expert, and yes, it does seem that you talk more than you photograph. How that involves the rest of the community, as you have tried to rally them to believe, remains unclear.

And to the polite question about tanning vs. staining, it is my understanding that the former was thought to be due the coupling of a developer molecule with gelatin in an oxidizing medium, whereas the latter was thought to occur as a result of two or more developer molecules joining together to form a dye in an oxidizing medium. The results are quite different, and not all developers capable of producing a relief image are capable of producing a stain image. You can find a trustworthy discussion of tanning vs. staining mechanisms in "Tanning Development and its Application to Dye Transfer Images," J. Photo. Sci (11), 1963, or you can rely on some of the "authoritative" opinions posted here.

In closing, and for the record, I do not mean to suggest that all opinions expressed here are inaccurate. That is certainly not the case, and I never said it was. Rather, I took the view that this forum was useful for sharing information, and for stimulating thoughts and questions whose answers I always preferred to verify by consulting independent and unquestionably reliable sources of scientific, peer-reviewed information. I see nothing wrong with that.

 

[sanking]

In closing, and for the record, I do not mean to suggest that all opinions expressed here are inaccurate. That is certainly not the case, and I never said it was. Rather, I took the view that this forum was useful for sharing information, and for stimulating thoughts and questions whose answers I always preferred to verify by consulting independent and unquestionably reliable sources of scientific, peer-reviewed information. I see nothing wrong with that.

You entered this thread with the statement that hydroquinone is not a staining developer. That is simply not a fact, as Tom Hoskinson pointed out. And, as I noted earlier, the information is in print as Gainer published something about it in Darkroom Techniques, and since that time his findings have been independently verified and reported by quite a number of people, including myself.

I also believe in the importance of reliable sources and peer reviewed information, but in this case there is more than sufficient documentation by persons with credibility in film testing that hydroquinone can be formulated as a staining developer, regardless of what the scientific literature may say. I suspect that the reason that the staining qualities of hydroquinone have not been widely reported in the past is due to the fact that most testing was done in high sulphite formulas that kill the stain.


Sandy

 

[srs5694]

Patrick Gainer published an article in Darkroom Tehcniques some while back (perhaps someone else will note the exact issue number) in which he reported that hydroquinone in low sulphite formulas can be formulated as a staining developer, and he gave a formula that proves his finding.

I'm not sure if this is the one you're thinking of, but the March/April 2004 issue of _Photo Techniques_ has at least one comment about this. It's in the formula description for CAT-P-
TEA (p. 26: 100ml TEA, 0.2g phenidone, 10g catechol). This formula is described as a staining developer, and immediately following the formula, there's this comment: "If you want to save money, you can use a like amount of hydroquinone in place of the catechol. (You can call this Q-P-TEA.)" This doesn't explicitly identify Q-P-TEA as a staining developer, but does by implication. Perhaps there's something more explicit in the body text somewhere, or in another issue.

Note that I'm not taking sides in this argument; I've never used CAT-P-TEA, Q-P-TEA, or any other staining developer, so I'm not qualified to comment. I'm just providing the reference.

 

[psvensson]

I'm not sure if this is the one you're thinking of, but the March/April 2004 issue of _Photo Techniques_ has at least one comment about this. It's in the formula description for CAT-P-
TEA (p. 26: 100ml TEA, 0.2g phenidone, 10g catechol). This formula is described as a staining developer, and immediately following the formula, there's this comment: "If you want to save money, you can use a like amount of hydroquinone in place of the catechol. (You can call this Q-P-TEA.)" This doesn't explicitly identify Q-P-TEA as a staining developer, but does by implication. Perhaps there's something more explicit in the body text somewhere, or in another issue.

Yes, there is. I don't have the issue in front of me, but he does say something like "Bet you didn't know hydroquinone can be a staining developer." He was right about that!

 

[NER]

We're talking about a compound discovered in 1880 and thoroughly researched in laboratories around the world in the 100 years that followed. One would think that if hydroquinone produced a stain image of the kind that remains with a PMK negative bleached of silver vs. a general and nonspecific discoloration owed to the use of an improperly compounded bath, for instance, scientists working in the aforementioned laboratories would have gotten around to reporting that, particularly if the stain image were one of any importance. [For the benefit of unlikely reader whose "ignorance of the literature" exceeds my own, "improperly compounded bath" refers to the use of developers without sulfites sufficient to protect against oxidation, the products of which are colored in several cases and capable of tinting emulsions, but not producing a permanent stained image proportional to silver density.] I have not seen the "View Camera" article recommended, but I will look at it. Aside from that article, the interpretation of which has been called into question above, all we have for the moment is the statement that the staining action has been verified by others. In the absence of reliable sensitometric or other proof, I defer to Mees, Tull, Neblette, Hauff, Bogisch, Lumiere, Andresen, Haist and researchers of similar reputation whose reports were both authoritative and accurate, and did not - to the best of my current knowledge - mention anything about hydroquinone image stain.

 

[psvensson]

You're right. If experimental data aren't supported by the books, we really have to go with the books. We're really being disrespectful of a century of photographic knowledge by using hydroquinone this way.

 

[Canuck]

After reading all of this, another question comes to mind. The lack of people using HQ (relative to its cousins), in the past, was it becuase of the archival quality of the negs produced? How archival are stained negs compared to those developed in non-staining developers?

 

[skahde]

You're right. If experimental data aren't supported by the books, we really have to go with the books. We're really being disrespectful of a century of photographic knowledge by using hydroquinone this way.

My thoughts exactly. Follow the authorities and stop experimenting. Who's that Francis Bacon anyway?

Best

Stefan

 

[Tom Hoskinson]

After reading all of this, another question comes to mind. The lack of people using HQ (relative to its cousins), in the past, was it becuase of the archival quality of the negs produced?

No.

 

[Tom Hoskinson]

My thoughts exactly. Follow the authorities and stop experimenting. Who's that Francis Bacon anyway?

Best

Stefan

Yeah! Never go with the data! Always go with arguments from authority!

 

[Helen B]

Norman wrote:
"...I defer to Mees, Tull, Neblette, Hauff, Bogisch, Lumiere, Andresen, Haist and researchers of similar reputation whose reports were both authoritative and accurate, and did not - to the best of my current knowledge - mention anything about hydroquinone image stain. ..." My emphasis.

Before I quote something else, I'd just like to say two things:

-I'd trust the guys here who say that hydroquinone forms a stain image even if I didn't already know it, and

-few of the standard texts (or at least those I have) go into much detail on stain images, if they mention it at all, but they do cover tanning. Tanning and staining may not be the same, but they are similar, and if the developer oxidation product is coloured then there is likely to be a link between tanning and the formation of a stain image.

OK, so on to L P Clerc's Photography Theory and Practice, 1971 edition revised by R. E. Jacobson, Vol 4, Monochrome Processing:

"573. Oxidation Products of Developers; Tanning; Secondary Images.
The quinonoid oxidation products of developers that are formed in the absence of sulphite, or in the presence of very low concentration of sulphite, are deposited in the gelatine at the site of development, and in a quantity proportional to the amount of silver halide reduced. Usually they polymerize, giving rise to coloured, tanning substances of the nature of humic acids, whose exact constitution is unknown.

After removing the silver image ... a yellow or brown secondary image remains, which, though it may not appear very intense to the eye, can give acceptable prints on high contrast paper because of its absorbtion of actinic light. The following table (Lumière and Seyewetz, 1928) shows the colour of the secondary image obtained in various developers, its relative intensity and the concentration of sulphite necessary to prevent its formation.

Developer -- colour -- relative intensity -- sulphite g/litre

Pyro -- yellow-orange -- 10 -- 11
Catechol -- black -- 10 -- 6
Hydroquinone -- yellow-brown -- 10 -- 2
Chlorhydroquinone -- yellow-brown -- 10 -- 2
Amidol -- reddish-brown -- 8 -- 2
p-Aminophenol -- brownish-black -- 3 -- 2
Metol -- brownish-black -- 2 -- 1
PPD -- Grey -- 1 -- 0
Glycin -- None."


Best,
Helen

 

[psvensson]

Thanks, Helen! It's interesting to see that they rate the intensity of the hq stain the same as pyro and catechol. And metol stains too!