Amidol

Chemical Name (6R,7R-3-Carbamoyloxymethyl-7-[2-(2-furyI )-2-(methoxyimino)acet-amidol -ceph-3-am-4carboxylic acid... 

The literature is most prolific on neutral An amides, but neutral U and amides are also well documented. There are only few publications on amides,one being on three alkali metal amidouranate(VI)s. ° There is a paper on a compound (18) which couid be classified as of U° and two on mixed valence U /U amides (see Section 5.4 for these types). There are a number of articles on monocationic amidol/ tetraphenylborates, three on dicationic analogues, three on a cationic U salt and four on alkali metal amidoactinate(IV)s and three on corresponding U salts. For crystalline uranium amides containing only monodentate ct-bonded ligands, metal coordination numbers of 3-7 are... 

Metol (monomethyl p aminophenol sulfate), used in most developing solutions, can cause severe skin irritation and allergies. Phenidone-based developers are less toxic to the skin than metol, amidol, or pyrogallol. When developing powders are mixed, inhalation is a concern. 

For very low temperature processing a caustic solution of two powerful developing agents, such as amidol and pyrocatechin, may be required, as used in Kodak SD-22. 

When processing at high temperatures a mildly alkaline, buffered borax developer is recommended. Alkali-free developers of the amidol type or one of the mildly alkaline fine grain developers such as Kodak D-23 are preferable to those with normal alkali content. Additionally, a pre-hardening bath such as Kodak SB-4 Tropical Hardener Bath or a specially formulated tropical developer may be used. 

SA For many years you used pyro and Amidol. You were famous for the black Amidol stains on your fingernails. I noticed when I came in that your fingernails are no longer black. 

BW Pyro is a film developer, Amidol is for paper. Amidol makes the fingernails black. Pyro stains too, but you don t get your hands in it as much, it s a different kind of stain. Pyro is a dirty developer but it s very crisp and sharp. I stopped using pyro for about ten years, but I ve decided to start using it again. I just can t get the same results with other film developers. 

SA What caused you to switch from using Amidol ... 

Method 1. The classic developing agent for creating cold tones on bromide papers is amidol. However, PQ developers using organic antifoggant, such as benzotriazole, will also increase the amount of cold image tone in a print (Formulas Paper Developers, Blue-Black Developer). In either case the results are usually very subtle. 

As with two-tray development, the time in each developer can be varied, though the minimum time in the amidol is about 1 minute. However, too long in the water bath could result in streaking. A good starting point would be to develop the print for 90 seconds in the amidol, and 30 seconds in the water bath. Keep an eye on the shadow areas of the print. When they appear to be about 80% complete, move the print to the water bath. 

The best papers to use with amidol developer are old-style, soft emulsion papers, such as those with minimal hardener, silver-rich papers (papers without excessive dye sensitization), graded bromide papers, long-scale chloride papers, or specially coated papers such as David Lewis Bromoil Paper (see Resources). With any other paper, which is to say most modern chlorobromide papers, amidol works just as well, though not necessarily better than most other developing agents, or combination of developing agents—thus the controversy. 

Much has been written about amidol s tendency to both oxidize rapidly and to stain paper. My own experience using amidol is that it does not oxidize any fester than most other developers. According to Michael A. Smith, an expert on amidol, and David Lewis, a leading expert on the Bromoil process who uses amidol extensively, neither has experienced the rapid oxidation reported by some users. If anything, amidol should only be used for one session and then tossed. 

Amidol is also toxic—never put your hands into a solution of amidol either use tongs or rubber gloves. This is good advice for all photographic chemicals, including MQ developers. 

Further notes on using amidol will be found in the Formula section. 

Fresh lemon juice is sometimes useful in removing amidol stains. 

All three of the famous Westons—Edward, Brett, and Cole—used amidol paper-developing formulae. All three were famous for their rich blacks and full-scale print tones. All three used different amidol formulae. There is some confusion as to the formula each one used, and more than one has surfaced for Brett and Edward. It may be possible that they used different formulae during the course of their long careers. 

In any event, there is one similarity to all three of the Weston formulae. One clue as to how they achieved the quality for which they were famous. All three formulae use as much or more Amidol than other published formula. Indeed, Brett used to say he liked to use twice as much Amidol than called for in published formulae. He would throw in a healthy handful and if his blacks weren t rich enough he would throw in more. Perhaps this is the secret to usingAmidol the rest of us have missed More is better. 

Edward (top) and Brett Weston s Amidol formulae as given to Richard C. Miller. The handwriting is Richard s. 

Some of the chemicals can be obtained from photo suppliers. Less common chemicals, such as amidol and pyrogallol, can be obtained from various chemical suppliers. A few suppliers even specialize in photographic chemicals. Not all chemical suppliers will sell directly to the public. Some that do are listed in Resources. 

Notes Amidol is one of the finest developing agents for blue-black tones on soft-emulsion bromide paper. It is also capable of creating neutral-blacks with a fine scale and transparency in the shadows. 

Amidol is very soluble in water or sulfite. The keeping properties of amidol in solution can be improved by the addition of a weak acid, such as lactic or citric acid. Amidol is energized by sodium sulfite alone, without the necessity of adding any alkali. 

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