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By Rlibersky - 01:53 AM, 03-27-2006 Edit Rating: None
Please add more. I would like to have a formula that gives nice browns on papers.
By Kino - 04:53 PM, 03-27-2006 Edit Rating: None
These catechol formulas were apparently published in 1940. There were many of them. The most important one was:
catechol 1 g
sodium carbonate 20 g
water 500 ml
This one was used by professionals only from around 1900. In my family of professional photographers ( but in Germany and the Netherlands in general) it has been used since 1910. Amateurs used it for a short while, just after world war II, because of a shortage of chemicals. And I used it as a scientific developer in laboratories. It is a excellent developer. I modified it again and the result were published on the APUG site, together with a modified pyrogallol developer under non-staining developers. Although the catechol developer was not in use by amateurs, I think amateurs can use them because the lenses are coated nowadays and the problem of an excellent image of the effect of flare has disappeared. The developers were introduced on an APUG workshop yesterday in The Netherlands with participants from Belgium and the Netherlands. Requests were made to introduce it in France in an international workshop.
On the workshop I gave an overview of the properties of the developers and demonstrated it with actual prints. For the catechol developer we have the following properties: the silver image has a brownish color, because the silver deposit is extremely fine ( some people think it is stain, but it isn't; stain is a macro molecular phenomenon). The grain is quite fine, the fog level is extremely low, The image quality is high definition ( MTF values of near 100% over a wide spatial frequency range). No disturbing adjacency effects. The developer is compensating because of the HD effect. No contraction or expansioin in the developing process is necessary ( although it is certainly possible).
Ribersky asked for more formula (also for paper). If you want a brown color, you need a fine silver deposit. This has been done with catechol on paper too. Another one that has been used in the first part of the 20 th century in Europe is one based on glycine. And, use a paper based on silver chloride emulsion.
Jed
