Rodinal

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. Rodinal is a popular high acutance black and white developer and is used at different dilutions for development in rotary machines, by agitation, as well as for stand development. Rodinal was patented on 27 January 1891, making it the oldest film developer which is still commercially available. Novel at the time of its invention was that it is delivered as a liquid concentrate that had to be diluted and not as a powder. By changing the dilution the development speed can be greatly changed. This invention is the longest sold product for photography and is listed as such in the book of Guinness World Records. During the division of Germany the original manufacturer Agfa was split, becoming the ORWO company in East Germany, where Rodinal was sold under the name ORWO R09. After the insolvency of AgfaPhoto in 2005, production was taken over by the re-formed ADOX, which also purchased the trademark rights in the name in Europe (excluding France) and continues to sell the product under this name. Modern Rodinal contains the following chemicals as its main components: Rodinal is sold as a concentrate and has to be diluted before use. Typical dilutions are 1+25 (1 part Rodinal, 25 parts water), 1+50 and 1+100.