Health effects of Pyro?

[sanking]

If the stain just adds base fog, what gives the negatives their wonderful qualities?

I will test it and see how I like it. Thanks.

All pyro developers that I have tried, including ABC Pyro, PMK, WD2D, Pyrocat-HD and Pyrocat-MC, add proportional stain. Some of these developers are more prone to general, or B+F stain, if dilution and time of development are not appropriate.

Stain is only one of the attributes of pyro staining developers. Such developers also tan and harden the gelatin of the emulsion, which can lead to a more precise reduction that increases sharpness.

Sandy King

 

[k_jupiter]

Stain is only one of the attributes of pyro staining developers. Such developers also tan and harden the gelatin of the emulsion, which can lead to a more precise reduction that increases sharpness.

Sandy King

Perhaps why, even though I use a non-hardening ammonium based fixer, I have no isses with scratching on Efke 100 films? I have developed these films in both WD2D+ and PyroCat HD.

tim in san jose

 

[Snapshot]

There seems to be enough benefits to switch to pyro developers for almost all film develolpment. Unless I'm mistaken, it seems the major drawback of using pyro developer is toxicity. Is there anything else that I'm missing? I'm sure issues like general availability, having to mix you own and other related matters dissuade people from using them.

 

[Daniel_OB]

Being pregnant, I'm more worried about this than normal. I wear gloves when using Diafine and Rodinal now. Could I use Pyro or should I stay away until after the baby's born? I highly doubt I'll run the risk, though.

Without gloves you have more chance to get a new photographer..

 

[Roger Hicks]

Note that hydroquinone, a very common compound of developer solutions, has a toxicity in the same range as pyro. When in dust form, these two compounds can have real bad health effects if absorbed.

Have you any good data for this? My own very limited knowledge is that even in the places where they actually sythesise(d) hydroquinone, there is no persuasive, let alone conclusive, evidence that the stuff is significantly dangerous. Of course you may have better information than I.

As for the toxicity of pyro, I rather like the words of Mike Gristwood, late of Ilford: "There are some things you worry about your children doing, and some things you worry about doing yourself." He placed the use of mixed pyro developer in the former category, not the latter, though like any sane person, he would use all reasonable precautions in mixing it. Of course he was speaking on his own (very well informed) behalf, not as ex-Ilford.

 

[Michel Hardy-Vallée]

Have you any good data for this? My own very limited knowledge is that even in the places where they actually sythesise(d) hydroquinone, there is no persuasive, let alone conclusive, evidence that the stuff is significantly dangerous. Of course you may have better information than I.

As for the toxicity of pyro, I rather like the words of Mike Gristwood, late of Ilford: "There are some things you worry about your children doing, and some things you worry about doing yourself." He placed the use of mixed pyro developer in the former category, not the latter, though like any sane person, he would use all reasonable precautions in mixing it. Of course he was speaking on his own (very well informed) behalf, not as ex-Ilford.

I'm mostly relying on the EPA toxicity info of Hydroquinone:
http://www.epa.gov/ttn/atw/hlthef/hydroqui.html

I wouldn't swallow the thing.

And I have somewhere a toxicity study of a cross-section of photographic materials. I'll try to find it.

 

[sanking]

Have you any good data for this? My own very limited knowledge is that even in the places where they actually sythesise(d) hydroquinone, there is no persuasive, let alone conclusive, evidence that the stuff is significantly dangerous. Of course you may have better information than I.

What part of MHV's message are you questioning? Pyrogallol and Pyrocatechin are in the same class of reducers as Hydroquinone, and MSD data sheets clearly indicate that the three substances are very similar in terms of toxicity issues.

Virtually all reducers have some toxicity issues but if treated with reasonable care one should not IMO be concerned about normal use. By reasonable care I mean, don't breath the powdered chemical, and avoid to the extent possible prolonged contact with the skin. That should be covered by mixing the chemicals in a well-ventilated area, outside if in doubt, and wear gloves if you develop in tray. For most types of development (in tanks, tubes, etc.) it is easy enough enough to avoid any contact with the developer so gloves are probably not even necessary unless you keep your hands in the developer for long periods of time, as in shuffling in a tray for example.

Sandy King

 

[Roger Hicks]

I wouldn't swallow the thing.

I'll go along with that. But the toxicity data for hydroquinone specifically refer to the ingestion of large amounts, or industrial-scale exposure to dust. This is not, on my reading, the same as the toxicity of pyro.

 

[Roger Hicks]

What part of MHV's message are you questioning? Pyrogallol and Pyrocatechin are in the same class of reducers as Hydroquinone, and MSD data sheets clearly indicate that the three substances are very similar in terms of toxicity issues.

Virtually all reducers have some toxicity issues but if treated with reasonable care one should not IMO be concerned about normal use. By reasonable care I mean, don't breath the powdered chemical, and avoid to the extent possible prolonged contact with the skin. That should be covered by mixing the chemicals in a well-ventilated area, outside if in doubt, and wear gloves if you develop in tray. For most types of development (in tanks, tubes, etc.) it is easy enough enough to avoid any contact with the developer so gloves are probably not even necessary unless you keep your hands in the developer for long periods of time, as in shuffling in a tray for example.

Sandy King

Dear Sandy,

Your point is the same that Mike was making, and that I attempted unsuccessfully to convey: no problem in normal use. My own reading -- which may be biased from preconceptions, plus the almost complete absence of reports of problems in hydroquinone fabrication (Kodak) -- is that pyro is a good deal more dangerous as inhaled dust than hydroquinone.

Cheers,

Roger

 

[sanking]

Dear Sandy,

Your point is the same that Mike was making, and that I attempted unsuccessfully to convey: no problem in normal use. My own reading -- which may be biased from preconceptions, plus the almost complete absence of reports of problems in hydroquinone fabrication (Kodak) -- is that pyro is a good deal more dangerous as inhaled dust than hydroquinone.

Cheers,

Roger

Hi Roger,

You may be right about the inhaled dust issue, but in the absence of compelling evidence to the contrary, and given the close chemical similarity of hydroquinone to both pyrogallol and pyrocatechin I am still inclined to believe that inhaling one is about as dangerous as the other. I strongly advise against inhaling any of these chemicals and recommend that one take positive measures to not do so.

We appear to be in agreement that in normal use there should be no problem in careful use of developers containing any of the three substances, or of most other reducers which may have toxic issues.

Best,

Sandy

 

[Roger Hicks]

Hi Roger,

You may be right about the inhaled dust issue, but in the absence of compelling evidence to the contrary, and given the close chemical similarity of hydroquinone to both pyrogallol and pyrocatechin I am still inclined to believe that inhaling one is about as dangerous as the other. I strongly advise against inhaling any of these chemicals and recommend that one take positive measures to not do so.

We appear to be in agreement that in normal use there should be no problem in careful use of developers containing any of the three substances, or of most other reducers which may have toxic issues.

Best,

Sandy

Dear Sandy,

We are in almost complete agreement. Our only difference is in our analysis of the relative dangers -- but as we agree that it would be extremely foolish to inhale either pyro or hydroquinone, I think our disagreement may be taken as trivial.

Cheers,

Roger

 

[Marc .]

Read the Safety Cards !

Hello,

Please read the Safety Cards if you use these chemicals.

What is called 'Pyro' can be either Pyrogallol = Pyrogallic Acid (in many pyro devs)
or Pyrocatechol = Cathechin (in Pyrocat-HD), a different chemical.
Compare them now to hydroquinone...
They have so many other technical names the 'CAS' number is the best to prevent mistakes.

International Safety Cards
http://www.cdc.gov/niosh/ipcsneng/neng0770.html
http://www.cdc.gov/niosh/ipcsneng/neng0411.html
http://www.cdc.gov/niosh/ipcsneng/neng0166.html

EPA Cards
http://www.epa.gov/ttn/atw/hlthef/pyrocate.html
http://www.epa.gov/ttn/atw/hlthef/hydroqui.html
nothing on Pyrogallol there

Oxford U. Cards
http://ptcl.chem.ox.ac.uk/MSDS/TR/1,2,3-trihydroxybenzene.html
http://ptcl.chem.ox.ac.uk/MSDS/CA/catechol.html
http://ptcl.chem.ox.ac.uk/MSDS/HY/hydroquinone.html


Marc

 

[Chris Breitenstein]

If the stain just adds base fog, what gives the negatives their wonderful qualities?

I will test it and see how I like it. Thanks.

This is just with PMK. How dark the film is stained is determined by how oxidized the developer is. this is why the second batch of film through a given tray of pyro is always more heavily stained then the first. With PMK the stain comes from the second dip into the developer after the film has been fixed. It is this additional staining that adds base fog. Which increases print exposure time and lowers contrast. With ABC & Pyrocat-HD the stain is added in proportion to the exposure density, which will in effect increase contrast. This is nice because you can now reduce development in order to maintain highlight detail, avoid bullet poof negs and still be able to print a full range of densities on grade two or three paper. This proportional stain also has many benefits when working with alternative and historic processes. There are some very informative articles on Pyro, it's stain, and the benefits on many sites. One of them is Unblinking eye. They have many articles written by Sandy King.

I would definitely encourage you to test anything you can get your hands. Find a film and developer combo that works for you and your vision. Good luck.

Yours;

 

[SPS731]

I'm convinced that I need to experiment with Pyro. Which formula would be good to start with? I've seen Wimberleys Wd2d+, Pyrocat-HD, ABC, and PMK mentioned in the discussion thread. Also, is there a good source for the formulas?

As far as the health concerns go, I also wonder about breathing the fumes of the different photographic chemicals!? Even with good ventilation they can be strong. In today's world it seems like everything is reported as a health risk, but the known toxicity of certain chemicals we deal with probably can't be good for us over the course of many years of exposure.

I'm definitely not going to give up photography, or go digital over the concern! But it something I wonder about.

 

[gainer]

PMK uses pyrogallol and the Pyrocat series uses pyrocatechin, AKA catechol. You can get them ready mixed or in a kit to make them from Photographer's Formulary. "The Book of Pyro" is worth getting, even if you do not use PMK.

Once the powders are dissolved in either water or propylene glycol stock solution, there is extremely little vapor pressure of the bad stuff above its surface. You will not be using more than an ounce of the stock solution mixed with 50 or more ounces of water. Be careful, but don't be afraid. You can easily do the process without endangering anything but the film, and even that requires a blunder.

 

[noseoil]

After using PMK and Pyrocat -hd, my preference for most development now is with Pyrcat-hd. It has better staining properties (no problems with muddy shadows as with PMK, just image stain), is inexpensive and most importantly for me, can be used for the stand type development methods. I still like PMK for portraits with certain films. tim

P.S. If you need to wear foul weather gear to work in the darkroom, get a different hobby. Take the reasonable precautions as listed above and enjoy some truly wonderful developers which exist.

 

[SPS731]

Thanks everyone for the wonderful information. I guess I'll start my pyro journey with Pyrcat-hd. I'm looking forward to seeing the results!