MQ-Tea

[Alan Johnson]

I found the thread where I tried HQ stain , it was faint,post 15 and Pat Gainer made some comments posts 18, 21.
(there was a url link here which no longer exists)

 

[Gerald C Koch]

The data quoted above from Lumière and Seyewetz, 1928 may explain why hydroquinone is not used as a staining developer. Both pyrogallol and catechol are more tolerant of the sulfite concentration, 11 and 6 g/l respectively. This contrasts with hydroquinone which is stated at 2 g/l. A hydroquinone based staining developer would oxidize very quickly. In addition any series of experiments keeping the sulfite concentration constant (say at the catechol value of 6 g/l) WOULD come to the conclusion that hydroquinone produces a lesser amount of stain.

Unfortunately we appear to know little about the controls used for the evaluation. Is the amount of developing agent a molar constant and is the pH of the developer always constant. Interesting data but there are too many variables of which we know very little. For example, was the length of development keeps constant. This is important since hydroquinone has a lengthy induction period. Once again one would conclude that hydroquinone produces less stain.

 

[Gerald C Koch]

As it was pointed out in another thread, one has to be careful since TEA is sold in 4 different forms. Substituting among them can cause problems.

o Pure 99% TEA
o Technical grade containing ~15 % DEA. Produces a higher pH than the pure form.
o Pure TEA with 15% water added.
o Technical grade with 15% water added.

The last two forms contain water to lower the viscosity. It is always best to read the MSDS to see what one has. If one wishes a waterless concentrate then the last two should be avoided.

I buy the pure form from The Chemistry Store, www.chemistrystore.com . They sell to people who make soaps and lotions so the product cannot cause skin irritation.

 

[Gerald C Koch]

Adding a reducing agent like ascorbic acid to a staining developer would reduce that amount of stain. In this respect it would work the same as increasing the amount of sulfite. This also applies to other developing agents like metol which are also reducing agents. Things get complicated very quickly when one gets to three developing agents. What percentage of the stain image is produced by each of the three developing agents?

 

[mrred]

I will get on this in the morning. Eyes a little too crossed for that meter right now...

 

[Gerald C Koch]

I have been giving some thought to the question of the stain capabilities of various developing agents. The data that is needed must be from a series of controlled experiments. Anything else is mere conjecture. Toward this purpose I have made a list of requirements for any serious experiments.

1. The test developers must contain only one developing agent.
2. The concentration of the developing agent must be expressed in millimoles.
3. All the test developers must contain the same known concentration of developing agent.
4. All the test developers must contain the same known concentration of sulfite.
5. The pH must be known and the same for all test developers.
6. Exposure of the test films must be known and constant.
7. Development parameters must be the same for all tests, ie time, temperature, agitation.
8. Negative densities must be made with a densitometer.
9. Measured negative densities must be independent of stain color (blue filter).
10. The density of each negative must be expressed in known units and not as a relative value.
11. Each test must be performed at least 3 times and the results analyzed statistically.

This represents a great deal of work but the data should very useful. Anyone up to the challenge?

 

[Gerald C Koch]

Unfortunately for any of us items 1-11 range from impossible to difficult to problematic at best.

It would make a good master's thesis though.

 

[el wacho]

I'm thinking of posting my formula in the articles section. I'm going to call it Koch hq staining developer in honour of you Gerald. Perhaps you could add it to that big pile of staining formulas you have...

 

[Alan Johnson]

Well, Pyro-Ammonia was introduced in 1862, maybe one of those old timers did it.
http://www.earlyphotography.co.uk/site/gloss9.html

 

[mrred]

What is the pH of your working solution?

9.1 on my freshly calibrated meter.

 

[mrred]

Gerry, you have (and always) provided useful information. If this thread explores the deepest darkest secrets of this mystery, fine. However I am at best a hack and literally was just curious enough to try.

I originally went with tea as I knew this would oxidize on it's own too quickly. There was no advantage to go with glycol becease every alkali I may need to try would be above what I would get with TEA.

What I have taken from my runs is....

1. The stuff does oxidize fast. Maybe too fast to be useful. It would start to go dark within 1 min just sitting in a mixing beaker.
2. My first observation (1:100 @ 10 mins) was a development of the leaders but not even the film markings were visible. To me, this was not so much a PH problem as that it needed a buffered alkali.
3. My third observation with double (1:50 @ 10 mins) I had consistent but under development. It could be from conclusion in 1 or 2

My next steps are to go with a buffered alkali and then to a much higher ph.

My logic is just to ballpark something. It's not total guesswork but not stabs in the dark either. If I get something useful then I will worry about the details.

 

[Gerald C Koch]

I'm thinking of posting my formula in the articles section. I'm going to call it Koch hq staining developer in honour of you Gerald. Perhaps you could add it to that big pile of staining formulas you have...

Checked and at present I have accumulated 50 formulas. Not quite a pile perhaps a mound. So if anyone has a formula name then there is a decent chance that I can supply the formula.

 

[Wayne]

I'm interested in the topic of staining hydroquinone developers, so I'll just add that I tried Mehmet's formula from one of the linked threads (except I reduced the KBr proportionally and absent-mindedly used ~20% less carbonate because mine is monohydrate) on some x-ray film last night. This is essentially Pyrocat-HD with hydroquinone substituted for catechol. I have nothing to compare it to because I've never used a staining developer before, but I did get some brownish image stain and seemingly minimal general stain. Haven't tried to print them yet but they look more agreeable than anything I've done previously in x-ray (which isn't much, but all were developed in dilute rodinal or accufine).

Mehmet's formula is below.

I only had 20g of hydroquinone laying around so the amounts I used for part A are in ( ). I also used tap water from my well

A:
Distilled water : 400cc (300)
Sodium Bisülfite 5g (4)
Hydroquinone 25g (20)
Phenidone 1g (.8)
(dissolved in5cc
isopropyl alcohol)
Pot. Bromide 1g (.3) (not sure why he used so much, but .3 is proportional to the 1 gram/liter used in Pyrocat-HD)
Water to make 500cc (300)

B
Distilled water 1000cc
Sod. Carbonate 200g
(anhydre)

 

[Rudeofus]

At that pH, without any sulfite, I would think what you have is basically a metol developer, but one which slows down as development progresses due to the build-up of metol oxidation products. The role of sulfite in both metol and particularly MQ developers is an interesting one.

I agree with this, mrred's experiment does not necessarily allow the conclusion that HQ doesn't stain at pH 9.1. It might well be the Metol which messes up things in this test. It would be interesting if this test could be redone with Phenidone instead of Metol.

 

[Wayne]

Is there any reason to believe it would be significantly different than catechol?

Is there any data about long term stability of this HQ stain?

 

[Rudeofus]

Is there any reason to believe it would be significantly different than catechol?

Since neither Catechol, nor Pyrogallol are particularly pleasant developers to work with from a safety stand point, there must be a strong reason why HQ's staining properties were never put to practical use. It may have been abandoned >100 years ago, and the reasons may no longer be known. Lack of stain stability may be one of the reasons.

 

[Wayne]

Seems this was addressed elsewhere by Gainer or someone else. It seems reasonable (to me, who barely managed a C the second time I took organic chem) to conclude that the reason it hasn't been put to practical use is because few knew it was a staining developer because of the small amount of sulfite required to eliminate that stain. Anyone experimenting with it at the level of sulfite used in pyrogallol or pyrocat would conclude it doesn't stain. True, these properties are mentioned in the scientific literature as far back as 1928, but who reads that ? There was one guy some years ago who swore up and down that it doesn't even stain simply because it wasn't in the literature (and then someone produced the literature). You may very well be right but I'm not sure why stain longevity has been singled out as the reason for it never becoming widely used. Is that in the literature anywhere, or has anyone reported it informally/anecdotally?

Since neither Catechol, nor Pyrogallol are particularly pleasant developers to work with from a safety stand point, there must be a strong reason why HQ's staining properties were never put to practical use. It may have been abandoned >100 years ago, and the reasons may no longer be known. Lack of stain stability may be one of the reasons.

 

[mrred]

Since neither Catechol, nor Pyrogallol are particularly pleasant developers to work with from a safety stand point

It's only dangerous to stupid people. Metol is dangerous to stupid people. Painting your house or cleaning your oven....filling your car up with gas..that's more dangerous.

Sent from my Nexus 5 using Tapatalk

 

[Gerald C Koch]

We can define stupid people as those who don't take adequate safety precautions. While Metol can cause dermatitis in some individuals it is safer than either catechol or pyrogallol. Pyrogallol is particularly dangerous since it is readily adsorbed thru the skin and is very toxic. It is known to attack the liver, kidneys and bone marrow. As I have said before the lethal does LDLo of pyrogallol is less than 2 grams for the average size man.

Perhaps to put this in perspective it puts pyrogallol in the same class as arsenic trioxide. This was the favorite method of dispatch for characters in Agatha Christie's murder mystery books. Ms Christie was an authority on poisons.

Catechol presents a somewhat different problem. Unlike hydroquinone it has a measureable vapor pressure at room temperature. Besides being dangerous from skin adsorption the solid should be used only in well ventilated areas.

 

[mrred]

Of course everything you said is factual; no dispute. But....how bright do I have to be to ingest 2g of pyrogallol? But then again people do job in high traffic areas. I guess with humans anything is plausible.


The point I was making is there is noting truly safe in the darkroom without safety precautions of some sort. Handled safely, crossing the street is more dangerous.

 

[Gerald C Koch]

The point I was making is there is noting truly safe in the darkroom without safety precautions of some sort. Handled safely, crossing the street is more dangerous.

I totally agree. People who should know better often do stupid things. The man who discovered the sweetener saccharin did so accidently. By not washing his hands after working in the lab and then eating a sandwich. The sandwich tasted very sweet. His curiosity led him to one of the chemicals he had synthesized that morning. Here the outcome was good but it could also have been very dangerous.

Pyrogallol is not only dangerous by ingestion but also by contact. The damage it causes can be cumulative. It was noticed early in the previous century that professional photographers had a shorter lifespan than other occupations. The most used developing agent then was pyrogallol. I personally consider it too dangerous to keep and use in one's house. If someone must absolutely use it then I would recommend the use of a pre-weighed kit to minimize contact with the solid.

 

[Wayne]

Yeah its an unfortunate fact that many people (not this thread) try to paint the pyros as no more harmful than other B&W chemicals. Sure its no more dangerous than anything if safety protocols are followed 100% of the time and there are no mistakes, but that doesn't make it inherently less toxic material. Its true the closely related HQ is the most toxic of the commonly used developer ingredients and should not be handled carelessly but even it it is not in the same toxicity class as pyrogallol or even catechol. That along with reduced cost is why I'm interested in its staining properties.

 

[Rudeofus]

Seems this was addressed elsewhere by Gainer or someone else. It seems reasonable (to me, who barely managed a C the second time I took organic chem) to conclude that the reason it hasn't been put to practical use is because few knew it was a staining developer because of the small amount of sulfite required to eliminate that stain. Anyone experimenting with it at the level of sulfite used in pyrogallol or pyrocat would conclude it doesn't stain.

AFAIK Hydroquinone is used in lith developers with almost no Sulfite and at rather high pH. I am surprised that nobody noticed any toning properties during all these tests and experiments with lith.

 

[Wayne]

Well that sent me on a search where I found this from Patrick Gainer on a thread about a "sort-of lith developer":

http://www.photography-forums.com/threads/hydroquinone-stains.93280/

" Hydroquinone used as in your formula is a tanning-staining developer in
the class of catechol. A small amount of sulfite will eliminate the
staining, but the staining is what gives it a warm tone effect. The
stain is redder than pyrogallol's and not as resistant to sulfite. The
stain is a dye formed when hydroquinone is oxidized, and it is quite
permanent AFIK."


This isn't the final word by any means, but since Patrick seems to have been the modern re-discoverer of the staining HQ developer it has some value.
It's a shame Patrick can't participate or do darkroom work anymore. His negatives from the early 2000s might be the "oldest" hq stained negatives that could be checked for their permanence.


Maybe I'll toss out this alternate theory: Could it be the stain color that renders it less popular than other staining developers? This will surely affect it's usefulness but it's too difficult of a thought experiment for me to carry to completion.

AFAIK Hydroquinone is used in lith developers with almost no Sulfite and at rather high pH. I am surprised that nobody noticed any toning properties during all these tests and experiments with lith.

 

[Wayne]

Interesting. Hydroquinone developers have long been used in staining nerve tissue. Google Bodian technique. Here's an example

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB0QFjAAahUKEwiYubDB5cHIAhWE2RoKHbpOBD4&url=http%3A%2F%2Flibrary.med.utah.edu%2FWebPath%2FHISTHTML%2FMANUALS%2FBODIAN.PDF&usg=AFQjCNFG2otS59lVlRQGlBdufAYJGjfyaA&bvm=bv.104819420,d.d24&cad=rja

I knew HQ is used in skin lightening but in the "I wish I didn't know this" category, I learned it is also used in something called anal bleaching. Apologies in advance. https://anusbleaching.wordpress.com/tag/hydroquinone/