If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Comparison of developer components
I just started putting together a darkroom and was reading the
Darkroom Cookbook last night to familiarize myself with paper develper chemistry. When I started to compare similar formulas, it occurred to me that it would be handy to index formulas by their components so that one could see the relationship between formulas more easily. That is, if the formula you were using contained 2g of metol, what other formulas also use 2g and how do they otherwise differ. This would seem to assist in following Mr. Anchell's "chef" approach to formula modification - tweaking measurements to meet particular goals. Has anyone created an index like this? Is there a good chemistry book that provides more detail on the effects of one restrainer versus another? On a related note - how do people like this book? I've used the Film Developing Cookbook for a few years and like the format a little better: providing formulas in with the description of the developer "families" makes more sense to me. It also seems to provide more background: sharpness vs grain, developer history, etc. |
#2
|
|||
|
|||
Comparison of developer components
"Mike Schuler" wrote
When I started to compare similar formulas, it occurred to me that it would be handy to index formulas by their components so that one could see the relationship between formulas more easily. That is, if the formula you were using contained 2g of metol, what other formulas also use 2g Sounds like a spread sheet to me. Columns for different ingredients. Rows for formula. Cells holding quantity. Sort as you like. -- 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/ |
#3
|
|||
|
|||
Comparison of developer components
"Nicholas O. Lindan" wrote in message ink.net... "Mike Schuler" wrote When I started to compare similar formulas, it occurred to me that it would be handy to index formulas by their components so that one could see the relationship between formulas more easily. That is, if the formula you were using contained 2g of metol, what other formulas also use 2g Sounds like a spread sheet to me. Columns for different ingredients. Rows for formula. Cells holding quantity. Sort as you like. -- 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/ I would also suggest comparing contents of _working_ solutions rather than stock solutions. Its interesting to make such comparisons if only because it shows how few real variations in developers there are. As far as properties of the various developing agents there is some information in older books on photographic chemistry. Most of the developers devised between the late 1920s and about the mid 1950's are Metol and Hydroquinone developers which vary mostly in their activity. Before about the 1920's the most popular film developer was Pyrogallic acid. Pyro developers originated about 1865, previous to that non-organic developers were used. About 1950 Kendall of Ilford found a way to make Phenidone economically. It has increased in popularity every since. About ten years ago ascorbic acid began to be used in commercial developers mainly as a replacement for Hydroquinone. Neither Ascorbic acid or Hydroquinone is very often used as a sole developing agent, I don't think Ascorbic acid ever is. Hydroquinone is used as the sole agent in several very high contrast developers and a couple of old very warm tone developers for paper. There are many thousands of organic compounds which are developers. Only a very few have ever achieved much popularity. Metol and Hydroquinone in combination can make nearly any kind of developer and is quite reliable. Phenidone and Hydroquinone makes similar developers which can have some advantages. Both Phenidone and Metol are used in combination with Hydroquinone because these form what are called superadditive developers, having more developing energy or greater capacity than either alone. Ascorbic acid is used with both Metol and Phenidone where it is desired to have a more environmentally friendly developer than a Hydroquinone containing one. The combination of Phenidone and ascorbic acid, as in Xtol has advantages of fine grain, good film speed and generally good tonal rendition. Agfa makes a Phenidone and Ascorbic acid print developer called Neutol Plus. The older version of Phenidone has been superceded by more stable forms such as Kodak Dimezone-S but their photographic properties are similar. In the 1930s, when 35mm photography first became popular, a number of developers claiming to produce extra-fine-grain were introduced. Most of these were based on para-phenylene diamine, mostly used in combination with other developers, most often Glycin. PPD does produce very fine grain but at the price of a substantial speed loss. When used as a sole developer the loss can be as great as five stops. When used with Glycin the speed loss is less but the grain is not as fine. As better film became available the use of this developer fell by the wayside. However, color developers are all related to PPD since it reacts with other substances to form dyes. Pyro is still popular among some photographers. Pyro, in the right kind of formula, produces a stain image which is in proportion to the silver image. The stain is yellow, brown, or greenish brown in color and holds back blue light to which printing paper is sensitive. A Pyro negative will usually print with greter contrast then it has visually. About the only other agents used much currently are Glycin, which can be used to make very warm tone print developers which have less speed loss than Hydroquinone developers, and Amidol, a very active developing agent which makes a good print developer in combination with sodium sulfite. Amidol tends to produce neutral colored images on many papers. Both Amidol and Glycin have become very expensive and do not have definite advantages so are not often used although there are photographers who swear by them. -- --- Richard Knoppow Los Angeles, CA, USA |
Thread Tools | |
Display Modes | |
|
|