35mm and pyro something

[Andrew O'Neill]

I have been using Pyrocat-HD for 15 years, always mixing it from scratch. There was a short time where I was mixing it with Glycol.. but I stopped because I was going through it very quickly. Glycol is great if you don't develop film so often.
I always handle this stuff carefully, from mixing up the chemicals, to developing. I have a vent hose over the mixing container, and I wear a respirator. When I develop, I wear gloves... even though my fingers never touch the stuff (tube development).
I've been quite happy with the results. I love the fact that the same negative can print nicely on VC paper, Kallitype, carbon transfer printing... and yes, scans very well. Pyrocat-HD is also a lovely developer for stand and semi-stand development.

 

[JWMster]

I've used apron, eye goggles, and chem suitable rubber gloves from day one. One set of gloves to mix, and then another after my break to let chems come to temp and I start the processing. So I am fairly careful even with the mild stuff - HC-110, DDX and FA-1027 that I've used.

So to me it sounds like pyrocat-HD is worth a shot. Have to admit ease of use and handling are also a factor, and then there's MC version and both HD and MC in glycol... just to make it simple. I may also try some of the other recommendations out there available in liquid or easy (beginner) mix kits from Photo Formulary or similar.

Petraio: I did read your article - especially the conclusion where he admits that while progress has been made, much may remain to be rediscovered in older formulations... a sentiment that sounds much more nuanced. That aside, suggestion of Adol's FX-39 may in fact be worth a try. Thanks!

 

[JWMster]

So if you do this pyrocat-HD, do you do it with glycol, or not? Thanks!

 

[Anon Ymous]

So if you do this pyrocat-HD, do you do it with glycol, or not? Thanks!

It's water, or propylene glycol and it's up to you to decide. If you plan to make a rather large quantity that will not be used within 1 year for example, then a glycol based version is a good idea. Otherwise, a water based solution is fine. By the way, it's the part A that we're talking about. Part B has indefinite shelf life and water is fine. The only thing that you might want to change is the concentration of part B. The normal concentration is rather marginal and some carbonate might precipitate, especially at lower temperatures. Halving the concentration takes care of that, but you need to double the amount used, ie 1+2+100 instead of 1+1+100.

 

[John Wiegerink]

So if you do this pyrocat-HD, do you do it with glycol, or not? Thanks!

Depends on how fast you use it. If you get a big batch you might want to go the glycol route as it will keep for almost ever. Still, Pyrocat-HD in water keeps extremely well also and is a little easier to work with due to less viscosity.

 

[John Wiegerink]

Anon hit the button just a tad faster than I.

 

[Rudeofus]

My impression is that Pyrocat HD (and variants) is one of the few published developer formulas using Phenidone as primary development agent, this alone may well explain its reported superiority over D-76 or Adox Borax MQ. This does not, however, make it particularly unique compared to e.g. Ryuji Suzuki's or Mark Overton's Phenidone+Ascorbate formulas.

 

[JWMster]

Won't know 'til i get sime, but thought you made it up like you do in a typical one shot of HC-110 ...it's for immediate use. Yes? If not, if yo don't just pour out what you need now... then glycol add- in is probably the right way to go.

 

[Andrew O'Neill]

Won't know 'til i get sime, but thought you made it up like you do in a typical one shot of HC-110 ...it's for immediate use. Yes? If not, if yo don't just pour out what you need now... then glycol add- in is probably the right way to go.

Pyrocat-HD has two stock solutions, A (contains catechol, etc), and B (potassium carbonate). You mix (usually) equal parts of A and B into water to make a one shot working solution. In my case, to develop two sheets of 8x10 film, I mix 10 ml of part A and 10ml part B into 500ml water.

 

[Andrew O'Neill]

My impression is that Pyrocat HD (and variants) is one of the few published developer formulas using Phenidone as primary development agent, this alone may well explain its reported superiority over D-76 or Adox Borax MQ. This does not, however, make it particularly unique compared to e.g. Ryuji Suzuki's or Mark Overton's Phenidone+Ascorbate formulas.

If they are not staining developers, then can't really put in the same boat.

 

[JWMster]

Pyrocat-HD has two stock solutions, A (contains catechol, etc), and B (potassium carbonate). You mix (usually) equal parts of A and B into water to make a one shot working solution. In my case, to develop two sheets of 8x10 film, I mix 10 ml of part A and 10ml part B into 500ml water.

So the shelf storage life of Solution A is what? And the glycol extends this? Someone I think (elsewhere) noted that HC-110 is as thick as it is due to glycol... and if that's the case I would just as soon do without it.

 

[Andrew O'Neill]

Yes, the glycol will extend stock A's life indefinitely. I would only recommend it if you develop infrequently. I don't recall it being as thick as HC-110. I don't bother with it as I go through the stuff quite quickly... and glycol costs and arm and a leg up here...even more to ship it up here.

 

[JWMster]

Great help! I am indebted. Many thanks to one and all for their input. Most kind and generous of you.

 

[Rudeofus]

HC-110 does not use Glycol, but Triethanolamine as liquid solvent. The assumption is, that oxidation takes place at a much smaller rate in organic solvents than in aqueous solution. So the trick is not adding Glycol/TEA to an aqueous stock solutiuon, but dissolving all the ingredients in Glycol/TEA from the onset. This severely limits the list of feasible ingredients in such developers and forces some formulas to start with two concentrates, but the extra longevity of the concentrate(s) may make it worth the effort.

About staining developers: if they are dilute and also tanning developers, they will likely increase sharpness, because tanned gelatin hinders diffusion, which leads to local developer exhaustion and the resulting Mackie lines. This effect has nothing to do with limited movement of silver ions or other explanations I have read here. Given that most explanations for the alleged small grain of staining developers are also questionable at best, I wonder whether there are solid and reliable measurements to back up these claims. It should raise eyebrows, that neither of the big, established photographic companies pursued this venue in the last 50 years.

 

[Petraio Prime]

HC-110 does not use Glycol, but Triethanolamine as liquid solvent. The assumption is, that oxidation takes place at a much smaller rate in organic solvents than in aqueous solution. So the trick is not adding Glycol/TEA to an aqueous stock solutiuon, but dissolving all the ingredients in Glycol/TEA from the onset. This severely limits the list of feasible ingredients in such developers and forces some formulas to start with two concentrates, but the extra longevity of the concentrate(s) may make it worth the effort.

About staining developers: if they are dilute and also tanning developers, they will likely increase sharpness, because tanned gelatin hinders diffusion, which leads to local developer exhaustion and the resulting Mackie lines. This effect has nothing to do with limited movement of silver ions or other explanations I have read here. Given that most explanations for the alleged small grain of staining developers are also questionable at best, I wonder whether there are solid and reliable measurements to back up these claims. It should raise eyebrows, that neither of the big, established photographic companies pursued this venue in the last 50 years.

Agreed!

 

[JWMster]

Agreed in principle, but the the deep pocket theory of litigation and liability with a hazardous chemical and small market may have also limited the reward to an extent that things of this nature are simply left to the boutique end of the market. Now if the hazardous nature were solved.... then the iPso facto might have more legs.

 

[Gerald C Koch]

Agreed in principle, but the the deep pocket theory of litigation and liability with a hazardous chemical and small market may have also limited the reward to an extent that things of this nature are simply left to the boutique end of the market. Now if the hazardous nature were solved.... then the iPso facto might have more legs.

The problem with this theory is that neither propylene glycol nor triethanolamine are particularly toxic. Propylene glycol is used in various liquid medicines as a solvent and TEA as an ingredient in hand lotions.

The HC-110 patent gives a formula that contains both ethylene glycol and diethylene glycol. The formula also contains DEA and TEA that serve a double role providing alkalinity and also additional solvency.

If you observe a tin can partially filled with water you will see that the rust first forms at the interface of the water and the air. The rust forms as a line around the inner surface of the can. It happens here because there is water and plenty of oxygen. Rust in the bottom of the can forms less slowly because there is less oxygen available. In fact rust will not occur in a completely water free environment. Kodak R&D took advantage of this fact to compound a developer concentrate very resistant to oxidation by merely avoiding water in the recipe.

Rodinal works on a slightly different principle. The very high concentration of salts severely restricts the amount of oxygen that can dissolve in the liquid. This was more serendipity rather than planning.

 

[Ian Grant]

So if you do this pyrocat-HD, do you do it with glycol, or not? Thanks!

I've done both, I made a double strength Part A in Glycol 6 0r 7 years ago to cut the weight while flying. However as long as your Metabisulphite is reasonably fresh and you use the right bottle (not low density plastics) I found Part A keeps up to 3 years just made up with water. I only discovered this as I kept some in my darkroom UK while living in Turkey, it finally collapsed just short of 4 years.

The free SO2 from the Metabisulphite prevents the Pyrocatechin from oxidisinig, once the metabisulphite has broken down to form Sulphite the developer collapes and oxidises rapidly.

Interestingly the formula for HC-110 has varied over the years, for a time it included Pyrocatech according to older Kodak MSDS.

Ian

 

[Rudeofus]

The problem with this theory is that neither propylene glycol nor triethanolamine are particular toxic. Propylene glycol is used in various liquid medicines as a solvent and TEA as an ingredient in hand lotions.

I believe, that JWMster referred to toxicity of Pyrogallol, not so much that of PG or TEA. Yes, Pyrogallol is plenty toxic, but Catechol would also work and is a lot less problematic. Kodak also appears not particularly afraid of selling toxic stuff to amateurs, if you look at KRST or their early color developers.

The HC-110 patent gives a formula that contains both ethylene glycol and diethylene glycol. The formula also contains DEA and TEA that serve a double role providing alkalinity and also additional solvency.

TEA is a ternary ammine and as such not a silver solvent. AFAIK the main silver solvent in HC-110 is Ethylenediamine. The biggest advantage of TEA over Glycol is the fact, that TEA binds with SO2 and Br-, and thereby provides a convenient way to get Sulfite into a developer based on a non-aqueous concentrate. Glycol won't do that, as exemplified by PC-Glycol, and a Hydroquinone based developer won't work without sulfite ion.

Kodak R&D took advantage of this fact to compound a developer concentrate very resistant to oxidation by merely avoiding water in the recipe.

Most photographic development agents are active mostly in their ionized form. This shows up as steady gain in developer activity as pH rises, and activity flattens out once a pH is reached where most developer molecules are fully ionized. Since there is minimal ionization of Hydroquinone and Phenidone in TEA, oxidation doesn't happen quickly. The same salting-out effect you mentioned with Rodinal may also help here.

 

[Rudeofus]

The free SO2 from the Metabisulphite prevents the Pyrocatechin from oxidisinig, once the metabisulphite has broken down to form Sulphite the developer collapes and oxidises rapidly.

Once the Metabisulfite turns into Sulfite, pH must have risen beyond 7 or 8, and at that pH most photographic developers will become very active reducers. If Sulfite would be more active at low pH, acidic fixers would have very long shelf life - they don't, to the contrary, neutral or alkaline fixers last much, much longer. Since Sulfite is used even in extremely alkaline developers like E6 CD, and it's used in E6 CD for no other purpose than to protect the CD-3 from oxidation, I would assume that it is active at all pH.

Interestingly the formula for HC-110 has varied over the years, for a time it included Pyrocatech according to older Kodak MSDS.

Even with Catechol in HC-110, it was never a staining developer, thanks to the copious amounts of TEA-SO2 in the concentrate.

 

[Gerald C Koch]

Perhaps I wasn't clear. By solvency I meant that TEA also acts as an organic solvent to dissolve various chemicals in the recipe not as a silver halide solvent.

 

[Alan Johnson]

AFAIK the main silver solvent in HC-110 is Ethylenediamine.

I think you mean the iminodiethanol-sulfur dioxide addition product?

 

[Ian Grant]

My impression is that Pyrocat HD (and variants) is one of the few published developer formulas using Phenidone as primary development agent, this alone may well explain its reported superiority over D-76 or Adox Borax MQ. This does not, however, make it particularly unique compared to e.g. Ryuji Suzuki's or Mark Overton's Phenidone+Ascorbate formulas.

Ilford published a few formula with Phenidone as the primary developing agent, Autophen and Microphen (ID-68) are the fine grain PQ developers, I'm not sure that it's the Phenidone that makes Pyrocat HD superior as it's the Pyrocatechin which is also a fine grain developing agent on its own that really gives it most of its benefits, the slight tanning and more importantly the staining.

Many Phenidone Ascorbate developers were published before Riuji Sezuki, and Mark Overton's developers, they are in various patents. Xtol was only released after one Patent (non Kodak) expired.

Ian

 

[Rudeofus]

I think you mean the iminodiethanol-sulfur dioxide addition product?

I must have mixed this up with something else. If I look at the current SDS, then I would consider the Ethanolamine as the most active solvent.

 

[Rudeofus]

Ilford published a few formula with Phenidone as the primary developing agent, Autophen and Microphen (ID-68) are the fine grain PQ developers, I'm not sure that it's the Phenidone that makes Pyrocat HD superior as it's the Pyrocatechin which is also a fine grain developing agent on its own that really gives it most of its benefits, the slight tanning and more importantly the staining.

Many Phenidone Ascorbate developers were published before Riuji Sezuki, and Mark Overton's developers, they are in various patents. Xtol was only released after one Patent (non Kodak) expired.

Yes, there are some published formulas, but on an absolutely minuscule scale compared to the spring flood of Metol based developer formulas. If you have access to underlying data of digitaltruth data, you will see the difference. In this regard, Pyrocat HD with Phenidone is more the exception than the rule, and the Phenidone may well explain why people coming from Metol based developers suddenly noticed an improvement with Pyrocat HD. Add the extra sharpness from high dilution and tanning, and I can understand that large format folks went all enthusiastic.