The Increasing Popularity Of Pyro.

[gainer]

Toxicity depends on a number of factors Patrick. Just as D-sugars and L-sugars differ in activity within the human body, but have the same formula should clue you in to this. Metabolic routes used by otherwise "identical" organic chemicals can cause havoc if used incorrectly.
PE

Yes, I know those things. Ascorbic acid is vitamin C, its mirror image is not, but both work equally well in developers. I just don't know why. If one knows why these things happen, one is more likely to be able to predict when they happen. If we put enough sulfite in a developer, we will not so easilly determine whether hydroquinone of catechol is the regenerator. They both stain when minimum sulfite is used, but the stain is of different color. The dye industry uses many colors that differ little chemically, I think.

I think it is safest to assume that anything we put into a developer is likely to be poisonous. At the same time, if the uses of a dangerous but managable drug in photography are sufficiently desirable, I would not choose agent over another simply on the basis of toxicity, although one I am particularly fond of has nothing but a pinch of Phenidone, a bunch of ascorbic acid, and a wad of borax in it. I used those terms just to tweak your sense of propriety.

 

[PhotoJim]

All I can speak about is my own experience.

I use PMK extensively, exclusively with traditional films (not t-grain emulsions) although some use it for t-grain films as well. I like the results. I like the tonality. I like how they print.

I like how PMK stock solutions last for years, which is convenient for this occasional worker.

I've used PMK for nearly a decade now and I've no intention of terminating its use, although D-76 and HC-110 do find a place in my darkroom for occasional use.

 

[Kirk Keyes]

Yes, I know those things. Ascorbic acid is vitamin C, its mirror image is not, but both work equally well in developers. I just don't know why.

I ain't no stinkin biochemist (so let my ignorance show), but it could be something as simple as what's called "stearic hinderance". Steric hindrance occurs when the size of groups within a molecule prevents chemical reactions that are observed in related smaller molecules.

So simply moving on -OH group that is attached to one position on a benzene ring to another may cause geometric effects that either favor or disflavor a particular reaction.

 

[KOG]

PS.
Howard Bond plays the trumpet.

I thought Howard played piano?

Kevin

 

[Keith Tapscott.]

Pyro developers are indeed good developers. I am not in a position to judge if they are superior to any existing non-pyro developer, but here are 3 cautions I have learned.

1. Pyrogallol and Catechol are two of the most toxic of all developing agents used in B&W.

2. The "stain" is a dye and as such can both improve and degrade the image. It can introduce a "blur" to the silver grain thereby reducing grain, but due to other effects it can appear to improve sharpness.

3. The stain is a dye and can fade with time. This is similar to a color film, no different.

PE

If the stain is a dye, then surely there must be some sort of post treatment of films to obtain a pyro or catechol like stain for films which have been processed in a non-staining developer if this is desired?

 

[Phillip P. Dimor]

I like the longevity and working dilutions of pyro, particularly the pyro pmk formula (of which it is the only one i've used). Smooth, crisp tonality. I'm not sure what the stain does at this point, honestly. I do remember having highlights that didn't block up as much but then again a lot of what I was printing while using PMK wasn't very demanding. Most of my detail was in the middle, or so I feel/felt at the time.

I'd use it again, except that I have a fair amount of Rodinal and other things. The $25 for the kit from photog. formulary is a deal but it's $25 I don't have right now.

 

[Photo Engineer]

If the stain is a dye, then surely there must be some sort of post treatment of films to obtain a pyro or catechol like stain for films which have been processed in a non-staining developer if this is desired?

There are! There are also many many staining type developers other than pyro types.

PE

 

[gainer]

I thought Howard played piano?

Kevin

He does that with the other hand.

 

[ic-racer]

3. When printing with variable contrast papers, pyro stain, which is always proportional to silver density, functions as a continuous variable color mask that reduces printing contrast, particularly in the high values. This allows shadow and mid-tones to be printed without compressing or blocking the highlights, reducing time spent burning and dodging. S King

Question for sanking: I am curious as to the magnitude of the effect. As I am sure you will agree, there are a lot of things that can be measured that don't affect print quality.

What method did you uses to test for that? I was thinking of using a series of evenly exposed frames of pyro-developed negatives as filters to determine the ISO(R) for each on Ilford MG paper. I think that would be pretty simple to do. Did you do something like that? Or did you measure spectral transmission of the stained negatives?

 

[gainer]

If the stain is a dye, then surely there must be some sort of post treatment of films to obtain a pyro or catechol like stain for films which have been processed in a non-staining developer if this is desired?

Simple. Bleach the negative in the same bleach you would use in the first part of sepia toning a print, but redevelop it to completion in the pyro or catechol developer of your choice. The silver image comes back with the stain. This is sometimes a good way to intensify a negative. Don't repeat it more than twice on the same negative. The same pyro effect that gives the hardened relief image can cause minute cracks in the emulsion.

 

[Photo Engineer]

Yes, redeveloping after bleaching can restore the stain, but it can also cause cracks.

HQ also causes some degree of relief image that can be documented since the early days of processing. It has been shown to be in part due to the relief image and in part due to the formation of the colorant or dye within the emulsion. This bulks up the emulsion imagewise just like Kodachrome and causes an enhanced relief image.

Good or bad, who can tell, but repeated treatment will eventually cause irreparable damage.

There is no magic bullet. There are always pluses and minuses.

And, steric effects in molecules is the answer as Kirk said. That is why there are two stereoicsomes of many organic chemicals and many straight isomers which do different things with the same identical formula. Some, like the vitamin C family are either good or inert, others are good or bad or inert in a similar fashion.

PE

 

[nworth]

This makes me wonder about staining developers without pyro. The advantage would be a less toxic developer. Any published formulas for a staining, non-pyro developer? While trying out a dilute low-contrast metol-carbonate-sulfite developer, I noted a significant stain in one instance, likely due to metol with very little sulfite, so it should be possible.

What immediately comes to mind are the chromogenic developers sometimes used for paper. You could use one of these without bleaching the silver out of the negative and get about the same effect. You could probably also use some variation on a color film developer with the couplers. Some combination of yellow and magenta couplers would produce a red stain in the image area to enhance the effective density. I'm not sure that it would have the same mask type of effect at pyro, however. As for toxicity, these developers use PPD derivatives, which are also toxic, but not as toxic as pyro. Here is an ancient example of the kind of developer I mean:

Focal chromogenic developer:
Diethyl-p-phenylene-diamine hydrochloride 2 g
Sodium carbonate 30 g
Sodium Sulfite 1 g
Potassium bromide 1 g
Hydroxylamine hydrochloride 1 g
WTM 1 l

Couplers:
Magenta
p-nitrophenyl acetanilide 500 mg
Acetone 12 ml
Ethanol (denatured) 100 ml
Brown
2,5,dichloroacetoacetanilide 500 mg
p-nitrophenyl acetonitrile 500 mg
Acetone 12 ml
Ethanol (denatured) 100 ml
Blue
alpha-napthol 700 mg
Alcohol 100 ml
Cyan
Dichloro alpha-napthol 1 g
Alcohol 100 ml
Green
2,4-dichloro-alpha-napthol 500 mg
2,5-dichloroacetacetanilide 500 mg
Alcohol 100 ml
Yellow
o-chloroacetanilide 1 g
Alcohol 100 ml
Yellow
2,5,dichloroacetanilide 1 g
Alcohol 100 ml

For use, mix 100 ml of developer with 10 ml of coupler and use as a one shot.

 

[Keith Tapscott.]

What immediately comes to mind are the chromogenic developers sometimes used for paper. You could use one of these without bleaching the silver out of the negative and get about the same effect. You could probably also use some variation on a color film developer with the couplers. Some combination of yellow and magenta couplers would produce a red stain in the image area to enhance the effective density. I'm not sure that it would have the same mask type of effect at pyro, however. As for toxicity, these developers use PPD derivatives, which are also toxic, but not as toxic as pyro. Here is an ancient example of the kind of developer I mean:

Focal chromogenic developer:
Diethyl-p-phenylene-diamine hydrochloride 2 g
Sodium carbonate 30 g
Sodium Sulfite 1 g
Potassium bromide 1 g
Hydroxylamine hydrochloride 1 g
WTM 1 l

Couplers:
Magenta
p-nitrophenyl acetanilide 500 mg
Acetone 12 ml
Ethanol (denatured) 100 ml
Brown
2,5,dichloroacetoacetanilide 500 mg
p-nitrophenyl acetonitrile 500 mg
Acetone 12 ml
Ethanol (denatured) 100 ml
Blue
alpha-napthol 700 mg
Alcohol 100 ml
Cyan
Dichloro alpha-napthol 1 g
Alcohol 100 ml
Green
2,4-dichloro-alpha-napthol 500 mg
2,5-dichloroacetacetanilide 500 mg
Alcohol 100 ml
Yellow
o-chloroacetanilide 1 g
Alcohol 100 ml
Yellow
2,5,dichloroacetanilide 1 g
Alcohol 100 ml

For use, mix 100 ml of developer with 10 ml of coupler and use as a one shot.

An interesting idea. Some people have reported excellent results when developing Technical Pan in C-41 developer. I`m sure the use of chromogenic developers (dyes?) might also be quite feasible for B&W films.

 

[Photo Engineer]

This type of process can also have the effect of "tanning" the emulsion just like Kodachrome. In fact, the 3 subtractive dyes above were used to make Kodachrome type images and were published in early texts such as Ledly and Stegmeyer.

They will work with C41 or RA developers quite well and with less toxic effect than the color developer given which was an early and very dermatitic color developing agent.

PE

 

[Kirk Keyes]

Question for sanking: I am curious as to the magnitude of the effect. As I am sure you will agree, there are a lot of things that can be measured that don't affect print quality.

What method did you uses to test for that? I was thinking of using a series of evenly exposed frames of pyro-developed negatives as filters to determine the ISO(R) for each on Ilford MG paper. I think that would be pretty simple to do. Did you do something like that? Or did you measure spectral transmission of the stained negatives?

The problem with using individual frames to make VC filters and then measuring the contrast range of a print made using those frames/filters is that the stain a negative is not constant, it varies with the density of the negative. The shadow areas have less stain than the highlights, so one filter will not be able to make a proper comparision.

I did some tests a few years ago to figure this out, and my approach was to expose and process some stepwedges. I measured the density of the pyro processed negs along with Ilford MG filters using a color densitometer and scanned them for absorbance vs. wavelength using a spectrophotometer, which I bought just for this test.

Using these techniques, I was able to determine the amount of "filtration" in the pyro-stained negative. I then assumed that the layers in my VC paper (Ilford MG IV FB) were pretty blue only or green only sensitive. That's a big assumption, but it simplifies the rest. (I planned to make a wedge spectrograph to actually measure the response of the paper with various multigrade filters, but never made it... I have the parts, so I'll do it someday for testing home-made emulsions.)

Using those measurements, I figured that the stain in the lower Zones of the neg was acting as about 10CC Yellow filtration, and in the higher Zones, there was about 40CC Yellow or so. (I'll have to look the numbers up if you want more precise values.) If you subtract out the base+fog stain from the neg, that ends up being about 30CC or so Yellow filtration that the stain is adding to the negative. For my MGIV FB paper, that ends up being about 1/2 to 1 grade when printing without any filtration.

So that means the highlights have a compression of about 1/2 to 1 grade of paper compared to the shadows. Or, if you add 30CC Magenta, you can filter out the yellow filtration of the highlights and then have about 30CC Magenta in the shadows, thereby increasing the shadow separation relative to the highlights. Keep in mind, the middle Zones, and split between these two extremes so there is not a big difference in fitration from the middle Zones to the highlights or the middle Zones to the shadows.

The measurements also indicate that developers with a stain color similar to PMK should give greater highlight compensation than ones with a stain color similar to Pyrocat. There is less difference in green absorbtion relative to blue absorbtion in Pyrocat stain than PMK.(Also, there is more UV absorbtion relative to blue with Pyrocat than PMK.)

 

[Photo Engineer]

Kirk;

Good idea, but the stain in pyro developers (and with HQ as well) has a large UV absorption component. I found this out when trying to print using Azo type emulsions. The exposure using stained negatives goes up very much more than one would expect if the stain were all in the visible. It does not go up as fast with an enlarging emulsion however.

This is my clue that there is a lot in the UV going on here. So, printers using contact (Chloride) papers, beware that all is not what you can see.

PE

 

[sanking]

The measurements also indicate that developers with a stain color similar to PMK should give greater highlight compensation than ones with a stain color similar to Pyrocat. There is less difference in green absorbtion relative to blue absorbtion in Pyrocat stain than PMK.(Also, there is more UV absorbtion relative to blue with Pyrocat than PMK.)

The measurements you did for absorption a couple of years ago and shared on either this forum or the LF forum were very consistent with my own comparison of the stain of PMK and Pyrocat-HD. I am not sure if that also applies to Pyrocat-MC since it has a very different color stain than -HD.

Sandy King

 

[sanking]

Question for sanking: I am curious as to the magnitude of the effect. As I am sure you will agree, there are a lot of things that can be measured that don't affect print quality.

What method did you uses to test for that? I was thinking of using a series of evenly exposed frames of pyro-developed negatives as filters to determine the ISO(R) for each on Ilford MG paper. I think that would be pretty simple to do. Did you do something like that? Or did you measure spectral transmission of the stained negatives?

As Kirk notes the effect depends on highlight density. If you develop to a very high CI the effect will be much greater than if you develop to a low CI.

My advice has always been to develop pyro negatives to a very high CI, say .70 or higher, and then control contrast with filtration if necessary. That way you will be able to take maximum advantage of the unique quality of highlight compression that is offered by staining developers.

Developing to a high CI is more practical with LF than 35mm since developing to a high CI with miniature film may give more grain than desirable.

Sandy

 

[Kirk Keyes]

Kirk;

Good idea, but the stain in pyro developers (and with HQ as well) has a large UV absorption component. I found this out when trying to print using Azo type emulsions. The exposure using stained negatives goes up very much more than one would expect if the stain were all in the visible. It does not go up as fast with an enlarging emulsion however.

This is my clue that there is a lot in the UV going on here. So, printers using contact (Chloride) papers, beware that all is not what you can see.

I only tested with a tungsten light (about 2850K) and only with Ilford MGIV. I could only extrapolate to other combinations of UV rich light sources or papers at this point. But I have not put any thought into that!

 

[Kirk Keyes]

I am not sure if that also applies to Pyrocat-MC since it has a very different color stain than -HD.

I have not tried the Pyrocat-MC.

If anyone is willing to send a couple of stepwedges processed in this developer, I can scan them and report.

Note: The submitted negs will most likely be destroyed in the testing process and will not be returned.

 

[Kirk Keyes]

My advice has always been to develop pyro negatives to a very high CI, say .70 or higher, and then control contrast with filtration if necessary. That way you will be able to take maximum advantage of the unique quality of highlight compression that is offered by staining developers.

I agree that this is good way to go.

 

[gainer]

The problem with using individual frames to make VC filters and then measuring the contrast range of a print made using those frames/filters is that the stain a negative is not constant, it varies with the density of the negative. The shadow areas have less stain than the highlights, so one filter will not be able to make a proper comparision.

I did some tests a few years ago to figure this out, and my approach was to expose and process some stepwedges. I measured the density of the pyro processed negs along with Ilford MG filters using a color densitometer and scanned them for absorbance vs. wavelength using a spectrophotometer, which I bought just for this test.

Using these techniques, I was able to determine the amount of "filtration" in the pyro-stained negative. I then assumed that the layers in my VC paper (Ilford MG IV FB) were pretty blue only or green only sensitive. That's a big assumption, but it simplifies the rest. (I planned to make a wedge spectrograph to actually measure the response of the paper with various multigrade filters, but never made it... I have the parts, so I'll do it someday for testing home-made emulsions.)

Using those measurements, I figured that the stain in the lower Zones of the neg was acting as about 10CC Yellow filtration, and in the higher Zones, there was about 40CC Yellow or so. (I'll have to look the numbers up if you want more precise values.) If you subtract out the base+fog stain from the neg, that ends up being about 30CC or so Yellow filtration that the stain is adding to the negative. For my MGIV FB paper, that ends up being about 1/2 to 1 grade when printing without any filtration.

So that means the highlights have a compression of about 1/2 to 1 grade of paper compared to the shadows. Or, if you add 30CC Magenta, you can filter out the yellow filtration of the highlights and then have about 30CC Magenta in the shadows, thereby increasing the shadow separation relative to the highlights. Keep in mind, the middle Zones, and split between these two extremes so there is not a big difference in fitration from the middle Zones to the highlights or the middle Zones to the shadows.

The measurements also indicate that developers with a stain color similar to PMK should give greater highlight compensation than ones with a stain color similar to Pyrocat. There is less difference in green absorbtion relative to blue absorbtion in Pyrocat stain than PMK.(Also, there is more UV absorbtion relative to blue with Pyrocat than PMK.)

There is a problem here, which might only be that it is 1:30 AM, but from what you are saying, it seems that if you bleached the silver out of a pyro negative and printed it, the printed image would also ba a negative. It seems to me, and agrees with my experiments, that the printed image would be a very weak positive, but positive nonetheless. To be otherwise would be a breach of conservation of energy.Only yellow light is coming through the negative, but less light energy is still getting through the more yellow parts than through the less.

 

[ic-racer]

The problem with using individual frames to make VC filters and then measuring the contrast range of a print made using those frames/filters is that the stain a negative is not constant, it varies with the density of the negative.

Yes, that is why a series of frames will be used. So, based on what sanking posted about hight CI, I'll go up to like 2.5 or so as the densest one.

The 'negative filters' of course will be used in front of a light source used to contact print a step wedge and thus determine ISO(R).

This will plot out nicely with the y-axis being ISO(R) and the x-axis being 'white light density of the negative/filter'. This should show the magnitude of the effect you are describing very well. It will presumably show that as the density increases there will be an effect on ISO(R). I presume it will be to increase ISO(R), that is to allow more blue light through, as that is what would be needed as the blue response of the MG paper is the most sensitive. But we will see.

Again to show hypothetical results:

Light/Filter ISO(R)

White(baseline) = 150
Film base = 150
base+.1 = 150
base+ .5 = 140
base+ .8 = 130
base+ 1.2 = 125
base+ 2.0 = 120

I don't think it will be anything this much of a change, but we will see.

In summary this is just a test of the color of the stain with increasing silver density. Rather than measure the color with a color probe, the color change is being tested by how it alters MG paper contrast (like a MG filter would).

Because of the claims that have been made, I presume someone has already done this test or something similar.

 

[Photo Engineer]

I suggest testing or somehow using such a test object with and without UV filtration to see what contribution the UV portion of the image has.

Also, I too believe that the bleached image should be a weak negative giving a weak positive image.

PE

 

[sanking]

I have not tried the Pyrocat-MC.

If anyone is willing to send a couple of stepwedges processed in this developer, I can scan them and report.

Note: The submitted negs will most likely be destroyed in the testing process and will not be returned.

Kirk,

Be happy to do that. Send me your mailing address in a pm and I will get them in the mail to you today or tomorrow.

Sandy