Pyrogallic acid

[David Vickery]

Hello, I bought a bottle of Pyrogallic Acid from Bryant Labs over a year ago and am getting close to an empty bottle. I recently purchased a new supply from Mike at Artcraft Chemicals. The Grade of the old bottle is "Crystal, Technical" and the grade of the new stuff from Artcraft is "Analytical Reagent 99.8% min. purity, powder". I didn't start using ABC pyro until this summer and when I did I was surprised to find that when I mixed my chemicals as others do my film had enough density to view the Sun with the Hubble. I had to dilute my chemistry to about 1:1:1:20 rather than the more common 1:1:1:7. Can the different Grades be enough to cause this difference in dilution? As far as I can tell everything else is similar to the way others use these chemicals except maybe that I use constant aggitation(I don't remember right now if that is different or not).

 

[c6h6o3]

What film did you develop in it and for how long?

 

[Jorge]

David this is a hard question as little amounts of pyro make a big change. Typically technical grade chemicals are in the 94 to 96% purity, so I find hard to beleive that a 2% difference in purity has made such a big difference in your developer strenght. But with pyro it could be possible. On th other hand how about your C solution, have you changed this? could you have made a mistake and mixed this stronger? Sodium carbonate is usually the culprit for things like this.
One more thing, could you have made a mistake when mixing sol A?
If you are using 1:1:1:20 then you would have oxidation very quickly in the developer. Have you seen streaks? have you seen more overall staining? examine all of this and let me know.

 

[edbuffaloe]

I am not a chemist, so take this as opinion only: pyrogallol is crystalline in nature. The powder form is simply pulverized crystals, so there should be no difference between the two forms in effectiveness as a developer. But be careful not to breathe the powder.

 

[avandesande]

I have seen tremendous differences in the way films react with pyro, unless we know what film he was using it's hard to guess what is going on..
Aaron

 

[David Vickery]

Hello, and thanks for your responses. The film that I have been using is HP5+. It sounds like you are saying that I have to be real careful when I mix my chemicals. I have always thought that if a little is good then a little bit more can only be better. I have really had to restrain myself with this stuff. Having thoroughly flunked college chemistry many years ago, I was wondering about the grades. If one is crystal and one is powder then it looks like the powder could absorb more water and then be less potent per weight??? Of course, they both look like powder to me.
As far as streaking goes, I don't really know for sure. I have had some of this but I was passing it off as bad technique or other mistakes, mainly because I was using what I thought was a large volume. Depending on the amount of film, anywhere from 2500ml to 4000ml.
At one point I thought that I had too much sol. C and so I reduced it for a couple of sheets and they turned out flat, but still as thick as kevlar.
When I first started with ABC pyro I didn't really do any formal testing. I just sorta started using it to get a feel for it. (I know what you're thinking,"that sure is a powerful tool to be in the hands of a moron") The first couple of sheets that I processed were thick enough to require me to hold a 300 watt Reflector Flood about twelve inches above the film for at least 60 seconds to get a decent amount of density in the print.
Things have improved somewhat and I will soon be out of HP5+ and will be using BPF200.

 

[Jorge]

It sounds to me you have high overall staining as opposed to proportional staining. Since you are able to see different contrast when using different amounts of C.
No, if a little bit is good a lot more is not better. So maybe you put too much pyro in solution A. One way to reduce the overall staining is to increase the sodium sulfite amount. Try increasing solution B. HP5+ is known for producing a higher overall staining than most films in pyro, so maybe your change to Bergger will help.
Another cause could be overexposing the negative. What EI are you using? Most people rate HP5+ at 160 to 200 but maybe your meter/developer/temp combination requires that you rate the film higher.

 

[c6h6o3]

If you're holding a 300 watt lamp that close to the printing frame then your negatives are too dense. Way, way too dense. No error in film rating or agitation procedure could account for such a difference. The densest negative I have gets 25 seconds on Grade 2 Azo with the lamp 3.5' away. Since the intensity of the light falls off proportionally to the square of the distance, just moving the lamp from 1' away to 3.5' away is equivalent to about 3.5 f-stops. Then you're giving it at least double my maximum. That's another stop. So you're at least 4 stops denser than my most bulletproof, contrasty negative. That's assuming that you're getting a good black at 60 seconds.

Have you developed any with the pyro you got from Mike? I bet that will solve your problem. Are you mixing it according to Michael Smith's instructions?

 

[Jorge]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (c6h6o3 @ Nov 17 2002, 10:37 PM)</td></tr><tr><td id='QUOTE'>No error in film rating or agitation procedure could account for such a difference.
</td></tr></table><span id='postcolor'>
I disagree, if David is rating the film at 100 and the EI he needs is 400 then there is two stops right there. If this is compounded with high overall staining for which HP5 is known for, I can easily see a 4 stop difference in density. I use HP5 as well as TMY 400 for my 8x10 and see a marked difference in overall and b+f staining between both films, HP5 being much greater than TMY.

As I understand it he is already using the pyro from Artcraft, thus his questions about the purity grade. I believe the problem lies with the mixing of the chemicals. Without knowing how much David put in each solution the most likely problem is oxidation of pyro and high overall staining.

 

[c6h6o3]

I was being conservative. The level of density he's talking about goes way beyond anything attributable to stain.

BTW, I get more fog stain with Bergger than with HP5+. This is probably due to the longer development times.

 

[Jorge]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (c6h6o3 @ Nov 18 2002, 09:43 AM)</td></tr><tr><td id='QUOTE'>I was being conservative. The level of density he's talking about goes way beyond anything attributable to stain.

BTW, I get more fog stain with Bergger than with HP5+. This is probably due to the longer development times.</td></tr></table><span id='postcolor'>
I dont know, I was once playing with a pyro formula I found in a focal press book, and let me tell you the negatives could be used for arc welding. They were correctly exposed and developed to the suggested time and boy were they thick. After a few negs I was tired of trying to tame the formula so I stop playing with it, but adding sodium sulfite helped a lot. Thus my reasoning about David's problem. There are many variables that need to be accounted for like temperature, concentrations etc, to be able to really trouble shoot this problem.

More stain with Bergger? .....hmm.....I am surprised...

 

[c6h6o3]

Admittedly there's something very strange going on with the stain I'm getting. The last batch I developed were in pyro from the last little bit of stock solutions in my jars. The sulfite was about 2.5 months old, but it had been sitting in the bottom of the jar for about 1 month of that. Add to that the fact that I changed fixers for this batch, and all bets are off. The stain on BPF 200 looked just like what I used to get with HP5+ in PMK; leprechaun green.

I plan to go back to Kodak Rapid fixer, mix up fresh pyro and then develop both HP5+ and Bergger. Then we shall see what we shall see. I'll keep you posted.

 

[avandesande]

I had nasty low contrast 'greening' when solution B was too old. I wouldn't recommend using it if its older than a month.
--Aaron

 

[Jorge]

I use Hutchings recommendation and just add 0.4 grams to solution C before I am ready to develop.

 

[john_s]

I mix my PMK accurately, but find that my contrast is excessive with Hutchings's recommended time. Conclusion? Don't know, but the best you can do is use accurate amounts, then test. Fortunately PMK lasts for ages, so you only have to test occasionally. Pyrogallol is rather more variable than most tech grade chemicals. The idea that if some is good then more is better is going to give you some very hard negs.

 

[c6h6o3]

Jorge-

What do you add .4 grams of to solution C? My solution C was a little weak, as there wasn't quite as much left in the jar as of the other two, and I always put it in last.

I wouldn't think that C would affect the stain that much anyway. Density yes, but it's the sulfite which affects stain the most and not the carbonate.

Jim

 

[avandesande]

Sodium carbonate solutions should keep indefinitly if they are protected from the air. If not, it can absorb CO2 from the air and turn in to sodium bicarbonate.
I have a theory that solution B slowly decomposes into a equilibrium mixture of sodium sulfide, sodium sulfite, and sodium sulfate.
As many of you know sodium sulfide will fog film..

--Aaron

 

[Jorge]

Pyro, instead of making the sodium sulfite solution, I just add 0.4 grams of sodium sulfite to solution C. This way my sulfite is always fresh.

Aaron you might be right I have not worked the redox reaction but sulfide is not far fetched. It could be an intermediate step in the oxidation of the sulfur ion into sulfate.

 

[c6h6o3]

Nice idea. I'll try it. Is that 0.4 gr for a one liter batch of working solution? (Don't make me do the math. It's too late in the day.)

 

[c6h6o3]

Wait a minute. Now I'm very confused. My Solution B stock is 105 gr / liter. Since I use 100 ml of stock/batch, that gives me 10.5 grams of sodium sulfite per liter of working solution. You're telling me to add 0.4 grams as a substitute for my Solution B stock? You can't be serious.

 

[Jorge]

you forgot the further dilution for the working formula. 10.5 grams add 700 ml of water and you get about 0.7 or 0.6 I dont know .....terrible doing figures in my head.

 

[c6h6o3]

No, I didn't forget. Each 1 liter batch of B stock solution contains 105 grams of sodium sulfite. When you dilute that by placing 100 ml of that B stock into 1 liter of working solution (1:10, since 100ml is 1/10 of 1 liter), you end up with 10.5 grams of sodium sulfite in the 1 liter of working solution. To substitute 0.4 grams for this is to be short on Solution B by more than an order of magnitude. Just what am I missing here?

 

[Jorge]

No no no......ok each liter of stock solution has 105 grams, this is aprox a 10% solution, agree?
Ok so now we take 100 ml of the stock solution, now we have only 10.5 grams...(10% solution). Were are now further diluting these 10.5 grams in 900 ml..(water+C+A) to make .105 concentration of sulfite aprox. In your previous post you missed a step.

Or in other words your calculations assume that 100 ml have 105 grams not 10.5 grams. Read your post again and you will see I am correct.

 

[c6h6o3]

All I really need to know is that there must be 10.5 grams of sulfite in the liter of working solution + 100 ml of Solution A (pyro, bisulfite and KBr) + 100 ml of Carbonate (solution C). So, I'll just mix 100 ml of the 10.5% sulfite solution for each development session and voila! My sulfite will always be fresh. Thanks for the tip, Jorge.

 

[Jorge]

Sure you are just making 100 ml of B stock solution everytime...you can do it that way or like me just add the pinch to the working solution.
In any case you will be using fresh sulfite everytime and will be more consistent....you are welcome.

OTOH hand it is not the working solution but the stock solution you are talking about. Please be aware of this. If you put 10.5 in the working solution you will get no stain....I promise you that.