Rodinal
Encyclopedia
Rodinal is the trade name of a black and white developing agent
produced originally by the German company Agfa based on the chemical 4-aminophenol.
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.
In November 2005 the plant was sold to a&o Imaging Solutions GmbH in Koblenz, Germany, who continued the production of Rodinal. In 2008 it was sold again to Connect Chemicals (Ratingen, Germany.)
Today Rodinal can be obtained from ADOX
Fotowerke Bad Saarow, Germany. It is now called ADONAL.
The most complete listing of Rodinal development times with a wide variety of films may be found at the Massive Dev Chart
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.
, because 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.
Photographic developer
In the processing of photographic films, plates or papers, the photographic developer is a chemical that makes the latent image on the film or print visible. It does this by reducing the silver halides that have been exposed to light to elemental silver in the gelatine matrix...
produced originally by the German company Agfa based on the chemical 4-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 (2010).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.
Recent history
Rodinal has for a long time been manufactured in a chemical plant in Vaihingen-Enz owned originally by Agfa.In November 2005 the plant was sold to a&o Imaging Solutions GmbH in Koblenz, Germany, who continued the production of Rodinal. In 2008 it was sold again to Connect Chemicals (Ratingen, Germany.)
Today Rodinal can be obtained from ADOX
ADOX
In photography, ADOX is a trademark with a long history. It was originally a brand name used by the German company, Fotowerke Dr. C. Schleussner GmbH of Frankfurt am Main, the world's first photographic materials manufacturer. The company's founder, Dr...
Fotowerke Bad Saarow, Germany. It is now called ADONAL.
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 even 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 Massive Dev Chart
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.
Acutance
A well-known property of Rodinal is its high acutanceAcutance
In photography, acutance is the edge contrast of an image. Acutance is related to the amplitude of the derivative of brightness with respect to space...
, because 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
Sodium sulfite
Sodium sulfite is a soluble sodium salt of sulfurous acid. It is a product of sulfur dioxide scrubbing, a part of the flue gas desulfurization process...
) to soften the granularity.