Rodinal

Rodinal is the trade name of a black and white developing agent produced originally by the Belgian company Agfa based on the chemical p-Aminophenol.

History

Rodinal was patented January 27, 1891 by Dr. Momme Andresen. It was the first product sold by Agfa and is the oldest photographic product still available (2008).After the patent expired, Rodinal has been supplied under different names by other companies. Rodinal is a concentrated liquid developer with very long storage life; the working developer is used once. This may have helped sales to amateur users who did not have to make up an entire packet of developer, enough for many films but with a short life once made up.

How to use

Rodinal is sold as a long-lasting concentrated liquid which is diluted with water for use, typically at 1+25, 1+50 or 1+100. Higher dilutions than 1+100 will slow down development and increase the perceived sharpness of the film. Working solutions can only be used once and will not keep evn if unused. Stand development of sheet films, oriented vertically with high dilution, no agitation, and extremely long developing times can be used for special purposes.The most complete listing of Rodinal development times with a wide variety of films may be found at the [http://www.digitaltruth.com/devchart.html Massive Dev Chart]

*See also: film development.

Edge sharpness

Rodinal increases perceived edge sharpness dramatically: since the developer is used up more quickly in dark than in light areas, development of light areas next to dark areas (the edges of the image) is reduced, increasing contrast at edges. Very dilute Rodinal (1 part to 100 or more) is often used to maximise this effect.

Rodinal is not a fine-grain developer, and is best used with film of low and medium sensitivity, with inherently finer grain than high-speed films.

High acutance

A well-known property of Rodinal is its high acutance, due to the fact that the Rodinal formula contains no silver solvent. Consequently the metallic silver in film, once developed, is left in its natural state, and does not undergo any "softening" by means of a solvent. It is not uncommon for photographers to add a solvent (such as sodium sulfite) to soften the granularity.

Recent history

Rodinal has for a long time been manufactured in a chemical plant in Vaihingen-Enz owned originally by Agfa. In November 2005 it was sold to a&o Imaging Solutions Gmbh in Koblenz, Germany. In 2008 it passed to CMS International. B&W chemical distribution is also done by the Rollei/Maco company [http://www.flickr.com/groups/rodinal/discuss/72157606051109157/] . Rodinal remains available from Fotohuis RoVo [http://shop.fotohuisrovo.nl/index.php?cPath=31_37] and possibly other sources.

References

External links

* [http://unblinkingeye.com/Articles/Rodinal/rodinal.html Ed Buffaloe's "Appreciating Rodinal" Article]