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#11
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PQ Stain
John Stockdale wrote:
I did read Patrick's item a few weeks ago with some skepticism, but this really does sound interesting. I suppose I've been mixing with water for so long that this concept seemed strange. Since your negs look not very contrasty but print with greater than expected contrast, I assume that they are stained like a pyro neg. What is the colour of the neg image? Brown and stained Did you use VC paper? No, Forte Fortezo G3 The reason for my asking is as follows: It used to be said the pyro negs gave smooth prints because the stain added to the silver grain (and gaps between grains), leading to good density with minimal development which of course leads to minimal grain. This was with graded papers. Nowadays with VC papers it is being said that pyro gives a built-in soft filter to control highlights, but the effect is not always desirable, since with VC paper the highlights can look flat with some subjects. I've heard that VC papers can do this as well, but also that the stain (usually) increases the density of the neg more than the colour of the stain decreases it even with VC... Have you used PMK? If so, how would you compare PMK with this new formulation? No, I haven't tried PMK, Patrick just emailed me tonight privately saying that he couldn't tell the difference between Catachol and Hydroquinone in Pyrocat-HD and that it is a safer and cheaper what to get what most people like about Pyro developers such as PMK. But perhaps you should ask him exactly what he thinks instead of me paraphrasing him as he has many years of experience with all of these developers. Did you do a measurement of film speed? No, but compared to the same roll I did in another developer this one seems to have full speed without exaggerated FB+F. I'm no chemist, Me neither but the formula of propyl glycol looks like an alcohol. Does it absorb water from the atmosphere? I note that its boiling point is 150degC, well above that of water and other common alcohols. So heating it could drive off water as long as it didn't decompose. The developing agents could also get cooked. How hot can you make it before any such troubles occur? Its a diol - a double alcohol. It doesn't seem to take on water because if it did it wouldn't last as long as it does. Wonder why then one has to heat it to expel the water as per Jorges comments on Patricks recommendations? Just what I wanted. Yet another developer to obsess over, just when I thought I had narrowed it down to two. Me too, I thought the same thing as soon as I developed these frames last night. I was happy with my other developer, but compared to these photos it looks like I've got a new favorite developer and it doesn't have any Vitamin C in it at all! |
#12
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PQ Stain
Just a couple of general comments here on Patrick's most recent developers to fill in some details about what Patrick, Nicholas and Jorge have been writing about. Hope you guys don't mind me piping up here to give a "bird's eye" description of this stuff. Many of you know about Patrick's developers from the article posted on the unblinkingeye.com web site. The ones he describes there are based on combinations of ascorbic acid (Vitamin C) and phenidone or metol, dissolved in various alkaline buffers (based on sodium carbonate or borax/lye mixtures). None of his formulas use sodium sulfite, which makes them very unusual in the developer world. Patrick's latest film developers are also based on simple combinations of developing agents and have also been formulated without any sodium sulfite at all. However, lately he has been using propylene glycol as a solvent (instead of water) to make up the stock solutions. The stock solutions don't contain any alkaline component or preservative (other than the Vitamin C itself). Part of the reasoning behind using propylene glycol is that a water-free stock solution inhibits the ionization of developing agents and reduces their tendency to be oxidized by air. The stock solutions won't develop film until they are diluted in water containing sodium carbonate, borax, or both. This is similar to the case of HC-110, another stock solution in a viscous organic solution. Patrick has found that HC-110 syrup (undiluted) does not develop film. Although the propylene glycol has to be heated to get the developing agents into solution, the developing agents don't crystallize out on cooling. Propylene glycol is pretty readily available from chemical suppliers, Photographer's Formulary, and also (pretty inexpensively) at www.chemistrystore.com. It is non-toxic -- used as an environmentally friendly antifreeze and as a base for cosmetic products, etc. It's a viscous liquid and is quite hygroscopic (it absorbs water vapour from the air). However, the amount of water absorbed isn't enough to cause problems. The stock solutions in propylene glycol keep for a very long time. The mixed developers give good film speed and fine grain. I've used the Vitamin C / Phenidone version on HP5 Plus, FP4 Plus, and PanF Plus with good results. The PanF looked especially nice. What Nicholas and Patrick have been discussing here are variants of these developers that contain hydroquinone. Patrick found that hydroquinone acts a staining agent in the absence of sodium sulfite. I don't know too much more about these experiments but they are very promising. The fact that hydroquinone acts differently in this case than it does in (say) D-76 isn't surprising. Hydroquinone is known to react with sodium sulfite in alkaline solutions to form a sulfite addition product. Hope I'm not spewing incorrect info here, Patrick or Nicholas should correct me if I am. Jordan (remove "pants" to reply) John Stockdale wrote: I did read Patrick's item a few weeks ago with some skepticism, but this really does sound interesting. I suppose I've been mixing with water for so long that this concept seemed strange. Since your negs look not very contrasty but print with greater than expected contrast, I assume that they are stained like a pyro neg. What is the colour of the neg image? Did you use VC paper? The reason for my asking is as follows: It used to be said the pyro negs gave smooth prints because the stain added to the silver grain (and gaps between grains), leading to good density with minimal development which of course leads to minimal grain. This was with graded papers. Nowadays with VC papers it is being said that pyro gives a built-in soft filter to control highlights, but the effect is not always desirable, since with VC paper the highlights can look flat with some subjects. Have you used PMK? If so, how would you compare PMK with this new formulation? Did you do a measurement of film speed? I'm no chemist, but the formula of propyl glycol looks like an alcohol. Does it absorb water from the atmosphere? I note that its boiling point is 150degC, well above that of water and other common alcohols. So heating it could drive off water as long as it didn't decompose. The developing agents could also get cooked. How hot can you make it before any such troubles occur? Just what I wanted. Yet another developer to obsess over, just when I thought I had narrowed it down to two. |
#13
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PQ Stain
Jorge Omar wrote: Patrick I have easy access to 98%~99% pure ethanol (I believe it's not purified through copper - CaO looks more like it if I remember right). How would that compare to Pglicol in your opinion? Besides, I would mix a stock alkali solution also. Thanks, Jorge Patrick Gainer wrote in : Nicholas, You may as well tell everyone what dilution and amounts of borax and carbonate you used. I just got and signed the contract for the article in Photo Techniques next issue, but I didn't describe the use of borax-carbonate. Makes me feel good that you like the results. We have been keeping the wrong thing away from developer in our efforts to preserve stock solutions. We worry about air, when we should be worrying about water. Keep the water away until the last minute. Dissolve hydroquinone or ascorbic acid or catechol or pyrogallol and/or phenidone in propylene glycol for the stock. I find it necessary to heat the mixture in order to dissolve the dry chemicals and to drive out water that may be in the glycol. This won't work with most alcohols which would boil away before the water. There is a method of dehydrating alcohol with anhydrous copper sulphate, but who wants to take a chance on having traces of copper in the developer? When you use a technical grade of propylene glycol, there may be water in it. When I first used heat to dissolve ascorbic acid, nothing much happened until I got the temperature up near 250 F. At that point, the ascorbic acid dissolved with evolution of steam. I was not sure whether or not there was an actual reaction with the ascorbic acid, and am still not. Because the glycol does not ionize the developing agents as water does. there is no noticeable loss of activity. Yes, glycols do take on water from the atmosphere, but not very rapidly and only from the atmosphere in the bottle, which cannot contain very much water. I did a life test of a phenidone-ascorbic acid-glycol developer which will be described in the upcoming article, which showed that after exposure to air of a thin layer of stock solution 100 mm in diameter for 16 days, the stock solution had lost no oomph. This is a rather extreme exposure. I don't know of any stock solution of phenidone and ascorbic acid. My interest was in sulfite-free developers. I have found that fine grain, excellent sharpness and good film speed can be obtained without any sulfite, and not just with ascorbic acid. Adding sulfite may actually increase graininess without increasing acuity. The staining-tanning developers include any that have two or more hydroxyl groups such as catechol, hydroquinone and pyrogallol. The staining is reduced by sulfite. Ordinarilly, sulfite is required for preservation, but not when a glycol or alcohol or even an organic base such as triethanolamine is used as a solvent for the stock solution. After water is added, there is a rather short life, but long enough for stand development if that is your cup of TEA. (Pun intended.) |
#14
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PQ Stain
"Patrick Gainer"
When you use a technical grade of propylene glycol, there may be water in it. When I first used heat to dissolve ascorbic acid, nothing much happened until I got the temperature up near 250 F. At that point, the ascorbic acid dissolved with evolution of steam. I was not sure whether or not there was an actual reaction with the ascorbic acid, and am still not. Ascorbic acid (vitamin C) is heat labile. I am not sure of the max temp it will stand but do know that boiling water will destroy it. I am afraid when it generated a puff, the acid went poof. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. |
#15
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PQ Stain
Nicholas O. Lindan wrote:
"Patrick Gainer" When you use a technical grade of propylene glycol, there may be water in it. When I first used heat to dissolve ascorbic acid, nothing much happened until I got the temperature up near 250 F. At that point, the ascorbic acid dissolved with evolution of steam. I was not sure whether or not there was an actual reaction with the ascorbic acid, and am still not. Ascorbic acid (vitamin C) is heat labile. I am not sure of the max temp it will stand but do know that boiling water will destroy it. I am afraid when it generated a puff, the acid went poof. My Merck Index gives a melting point of 190-192C for ascorbic acid with "some decomposition". We may be losing a small part of the ascorbic acid on dissolving it in the hot propylene glycol, but not much. The developer still works just fine. Aqueous solutions of ascorbic acid generally decompose quickly due to aerial oxidation. Destruction of Vitamin C in boiling water is probably just a heat-accelerated version of this. The vitamin C does not ionize in propylene glycol and this probably protects it. Jordan |
#16
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PQ Stain
I mixed my PA in Pglicol at some 80C (did not heath the Pglicol above that;
it's USP grade) 4 months ago. It's working quite well - as a matter of fact, just developed a test strip to test a recently repaired camera. Jorge Jordan Wosnick wrote in news:4031233e$0$573 : My Merck Index gives a melting point of 190-192C for ascorbic acid with "some decomposition". We may be losing a small part of the ascorbic acid on dissolving it in the hot propylene glycol, but not much. The developer still works just fine. Aqueous solutions of ascorbic acid generally decompose quickly due to aerial oxidation. Destruction of Vitamin C in boiling water is probably just a heat-accelerated version of this. The vitamin C does not ionize in propylene glycol and this probably protects it. Jordan |
#17
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PQ Stain
Patrick Gainer wrote
My interest was in sulfite-free developers. WAS? Why such exotic compounds such as brake fluid and antifreeze? At bedrock is the lifespan of at least the stock or concentrate. Why not some other scavenger of oxygen? Perhape an oxalate or even one of those used in preserving pharmaceuticals in water solution. Dan |
#18
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PQ Stain
"Jordan Wosnick" wrote:
Nicholas O. Lindan wrote: "Patrick Gainer" wrote: dissolve ascorbic acid ... 250 F ... evolution of steam Ascorbic acid (vitamin C) is heat labile. I am afraid when it generated a puff, the acid went poof. My Merck Index gives a melting point of 190-192C ... Destruction of Vitamin C in boiling water is probably just a heat-accelerated [oxidation] Mea Culpa. I am reading the wrong cookbook; Fanny Farmer's rather than Steve Anchell's. Thanks: "Say something stupid -- learn something new." -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. |
#19
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PQ Stain
Dan Quinn wrote: Patrick Gainer wrote My interest was in sulfite-free developers. WAS? Why such exotic compounds such as brake fluid and antifreeze? At bedrock is the lifespan of at least the stock or concentrate. Why not some other scavenger of oxygen? Perhape an oxalate or even one of those used in preserving pharmaceuticals in water solution. Dan Is there another one that is cheaper than glycol? Besides, glycols are not scavengers of oxygen. In addition, oxygen is not the only concern. Some developer solutions are unstable even when carefully protected from oxygen. The mere ionization of molecules into parts that can oxidize and parts that can reduce makes possible reactions that you may not want. In order to get the sulfite-free preservation of stock solutions one could use an alcohol, but it is difficult to keep alcohols from becoming 10% water. Pure alcohols are more expensive than glycol. Ethanol, for most of us, is subject to a liquor tax. Besides all that, it makes more interezting reading when I write about using antifreeze or brake fluid in developers. |
#20
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PQ Stain
I just had an out of town, 'acquaintance / photographer / accomplished
printer', in my darkroom so I could develop a roll of film that he used to test a camera he was thinking of buying... When I swung open the cupboard doors and there stood cans of gas line antifreeze, Red Devil Lye, 20 Mule Team Borax, Arm & Hammer Washing Soda, and Vitamin C powder, he started mumbling, "No way... This is a joke, right? Where's the D-76?"... Funny thing, after the negatives were hanging to dry and we were leaving he was still mumbling, " . . & the goddam negatives look great.. I don't believe this..."... Sorta like the day he found the Santa Claus costume in dad's closet... I'm not sure he will ever be the same... denny "Patrick Gainer" wrote in message Besides all that, it makes more interezting reading when I write about using antifreeze or brake fluid in developers. |
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