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#1
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To Richard K - Perceptol x Microdol
Hello, Richard
Could you comment in the (accepted) data that Perceptol uses an innordinate ammount of bromide vs Microdol using chloride? Thanks, Jorge |
#2
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To Richard K - Perceptol x Microdol
"Jorge Omar" wrote in message ... Hello, Richard Could you comment in the (accepted) data that Perceptol uses an innordinate ammount of bromide vs Microdol using chloride? Thanks, Jorge This is true according to the Material Safty Data Sheet on the Ilford web site. Microdol-X contains sodium chloride. Both the chloride and bromide act as fine grain agents in large amounts. I _think_ I saw an old MSDS for Perceptol which showed sodium chloride instead of bromide but am not sure and can't find it in my archived stuff. Haist mentions sodium chloride in his book but not bromide as a fine grain agent. Both developers have proprietary formulas but the chloride content of Microdol-X is evidently about 20 grams per liter. There was an earlier version called just Microdol. I don't know the difference for certain but think that the X version probably contains something to prevent dichroic fog. It may be that the bromide in Perceptol also does this. Both of these developers work as advertised. 100 T-Max in full stength Microdol-X is nearly as fine grain as Technical Pan in Technidol at more than double the speed and is less fussy about getting normal tonal range. -- --- Richard Knoppow Los Angeles, CA, USA |
#3
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To Richard K - Perceptol x Microdol
Richard Knoppow wrote: "Jorge Omar" wrote in message ... Hello, Richard Could you comment in the (accepted) data that Perceptol uses an innordinate ammount of bromide vs Microdol using chloride? Thanks, Jorge This is true according to the Material Safty Data Sheet on the Ilford web site. Microdol-X contains sodium chloride. Both the chloride and bromide act as fine grain agents in large amounts. I _think_ I saw an old MSDS for Perceptol which showed sodium chloride instead of bromide but am not sure and can't find it in my archived stuff. Haist mentions sodium chloride in his book but not bromide as a fine grain agent. Both developers have proprietary formulas but the chloride content of Microdol-X is evidently about 20 grams per liter. There was an earlier version called just Microdol. I don't know the difference for certain but think that the X version probably contains something to prevent dichroic fog. It may be that the bromide in Perceptol also does this. Both of these developers work as advertised. 100 T-Max in full stength Microdol-X is nearly as fine grain as Technical Pan in Technidol at more than double the speed and is less fussy about getting normal tonal range. I'm a long way from last using either dev, but from my early experiences I would have expected bromide or chloride to have acted as mild solvent agents with a restraining and buffering side-effect, with slightly more activity from bromide. Perceptol, which I used for a long time both straight and diluted, generally had a far superior resistance to aerial oxidation, and with the long dev times involved for 1+3 user (an extreme) with inversion agitation, that was technically better. Microdol-X generally proved slightly harder to dissolve, with more tendency to leaving a small residue needing filtering, and oxidised more rapidly in stock solution or diluted working solution. Kodak used the 'X' suffix to indicate films or processes which were in line with sensitivity revisions - originally, the X was used to indicate filmspeeds only. X indicated a speed approximately 32 ISO (pre-war), XX 64, XXX 125. With the changes in calculaton of filmspeeds using density above fog threshold in the 1950s, X became 64, XX 125 and XXX 250; further improvements in emulsions meant that Tri-X (XXX) increased to 320 - the rating which still applied to Tri-X Professional into the 1980s - and then 400 for general stock. Panatomic-X remained peculiarly stuck in the past and was only 32 ASA (ISO) and eventually the whole concept just got muddled so that no-one really remembers why Tri-X is called Tri-X! Plus-X, or course, was a little bit faster than X in the final stages where X meant 100, XX 200 and XXX 400. Whatever formulation changes were present, the X in Microdol-X probably got there as part of a marketing concept, and indicated the suitability of the developer for use with these films - but also implied a retention of filmspeed. Though Microdol-X (like Perceptol) incurs a loss of around 1/3 to 1/2 the conventionally measured filmspeed unless diluted, it was in its day far superior to strong solvent developers, which lost half to 2/3rds of available speed and also produced a very low acutance by destroying micro-contrast. But strong solvent developers were not averse to using sodium thiosulphate in the dev, being half way to a monobath. So the X probably just marked the spot... signalled that this was a fitting companion dev to Panatomic-X, Plus-X and the 'generation X' of films with their revised sensitivities. For anyone keen on experiment, in the 1970s I made an ad-hoc special effect developer by mixing a chromium intensifier bleach with a print strength MQ developer - in much the same way as a monobath. Negatives developed in this produce a direct posterization, with a distinct set of steps, but you have to start the development in a regular developer then transfer to the combined intensifier/redeveloper mix for the second half of the dev time. David http://www.freelancephotographer.co.uk/ http://www.maxwellplace.demon.co.uk/pandemonium/ |
#4
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To Richard K - Perceptol x Microdol
Thanks for the explanation, but I still find it intriguing how a
developer works with such a hig ammount of restrainer in it! Jorge "Richard Knoppow" wrote in news:VGUuc.18900 : This is true according to the Material Safty Data Sheet on the Ilford web site. Microdol-X contains sodium chloride. Both the chloride and bromide act as fine grain agents in large amounts. I _think_ I saw an old MSDS for Perceptol which showed sodium chloride instead of bromide but am not sure and can't find it in my archived stuff. Haist mentions sodium chloride in his book but not bromide as a fine grain agent. Both developers have proprietary formulas but the chloride content of Microdol-X is evidently about 20 grams per liter. There was an earlier version called just Microdol. I don't know the difference for certain but think that the X version probably contains something to prevent dichroic fog. It may be that the bromide in Perceptol also does this. Both of these developers work as advertised. 100 T-Max in full stength Microdol-X is nearly as fine grain as Technical Pan in Technidol at more than double the speed and is less fussy about getting normal tonal range. |
#5
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To Richard K - Perceptol x Microdol
Jorge Omar wrote in message . 4...
Hello, Richard Could you comment in the (accepted) data that Perceptol uses an innordinate ammount of bromide vs Microdol using chloride? Thanks, Jorge I doubt that. Sodium sulphite rather than potassium bromide. The latter is seldom used at concentrations exceeding 3g/litre in B&W developers. |
#6
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To Richard K - Perceptol x Microdol
"Michael Scarpitti" wrote in message om... Jorge Omar wrote in message . 4... Hello, Richard Could you comment in the (accepted) data that Perceptol uses an innordinate ammount of bromide vs Microdol using chloride? Thanks, Jorge I doubt that. Sodium sulphite rather than potassium bromide. The latter is seldom used at concentrations exceeding 3g/litre in B&W developers. Have a look at the MSDS. Perceptol contains a very large amount of bromide. I think the bromide in Perceptol and chloride in Microdol-X have about the same effect. They slow down the development. Neither is a halide solvent. There is considerable solvent action in both developers due to the high concentration of sulfite and long time of development. However, the effect of sulfite as a solvent is very often mis-understood. Sulfite has no significant action on the developed silver. Nor does it etch the corners off silver crystals. Rather, it removes a layer from the surface of the halide crystals and changes the shape of the developed metallic silver crystals. A small amount of solvent action, about what is found in D-76, causes an increase in film speed by exposing more development centers to the developer. More action, as in Microdol-X, Perceptol, or D-25 when they are used at full strength can dissolve some of the development centers, or in other words, destroy some of the latent image, causing a loss of some speed. When diluted this effect does not take place. Note that the developing times for these developers is quite long in comparison to developers without an extra-fine-grain property. This is the result of the very low activity of all three. The same thing is found in the old Para Phenylenediamine developers. PPD is very low in activity, about the lowest of any practical developing agent, and it is a halide solvent. A pure PPD developer may take more than half an hour to develope even modern film and will lose four or five stops. It does have finer grain than any other developer but the great speed loss and generally very low contrast made it impractical. Most of the practical PPD developers combined it with something else, often Glycin or Metol. These developers had no advantage over developers like D-25, Microdol-X, or Perceptol so fell out of use. Grant Haise discusses extra-fine-grain developers a little in his book _Modern Photographic Processing_. This book, which was long out of print, is available in an excellent reprint from the author. -- --- Richard Knoppow Los Angeles, CA, USA |
#7
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To Richard K - Perceptol x Microdol
Richard Knoppow wrote:
Grant Haise discusses extra-fine-grain developers a little in his book _Modern Photographic Processing_. This book, which was long out of print, is available in an excellent reprint from the author. Do you have an URL or any information about this? I searched in Google, but found only numerous references to the old books. Martin |
#8
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To Richard K - Perceptol x Microdol
Martin Jangowski wrote in message ...
Richard Knoppow wrote: Grant Haise discusses extra-fine-grain developers a little in his book _Modern Photographic Processing_. This book, which was long out of print, is available in an excellent reprint from the author. Do you have an URL or any information about this? I searched in Google, but found only numerous references to the old books. Martin Martin, I will post the info when I get home and can look it up. I got my copy from Grant. Richard Knoppow Los Angeles, CA, USA |
#9
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To Richard K - Perceptol x Microdol
Martin Jangowski wrote
Richard Knoppow wrote: Grant Haist discusses extra-fine-grain developers a little in his book _Modern Photographic Processing_. This book, which was long out of print, is available in an excellent reprint from the author. Do you have an URL or any information about this? I searched in Google, but found only numerous references to the old books. Martin Available from abebooks.com (great site for used & obscure books). $490 the set, though. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#10
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Quote:
The MSDS for Microdol-X reads as Elon/Metol, Sodium Sulphite, Boric Anhydride, Sodium Chloride and Sodium Hexametaphosphate(Calgon). You can find the components used for many Kodak developers on www.kodak.com/go/MSDS. and likewise with Ilford chemicals on www.ilford.com |
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