Grain development

Chono, M., I. Honda et al. (2006). Field studies on the regulation of abscisic acid content and germinability during grain development of barley Molecular and chemical analysis of pre-harvest sprouting. J. Exp. Bot. 57(10) 2421-2434. 

If the photolytic silver is added on to the material of the speck, the nuclei which are responsible for making a grain developable consist... 

The solvent action of sulfite tends to promote fine-grain development, and some of the commercially used fine-grain developers contain as much as 100 grams of sodium sulfite per liter. Some of these developers contain other solvents as well, e.g., thiocyanates and amines. Any of these solvents should cause some shift to occur in the relative rates of the... 

Kopnwa, B. M. (1975) A comparison of various procedures for fine grain development m electron microscopic radioautography. Histochemistry 44, 201—224... 

The coarse grains developed by conventional casting processes usually arc deleterious to fatigue life. For parls such as turbine disks that arc life-limited by latiguc rather than creep, fine grains are produced by powder metallurgical techniques. 

FIGURE 7. Relation between polarographic Er of dyes and the log of the exposure to blue light needed to make 1/3 of the grains developable exposure, 100 s. 

Development modifiers alter the rate of development (development accelerators or inhibitors) or may render silver halide grains developable. Certain complexes of ruthenium, in particular [Ru(NH3)6]Cl3, are accelerators of development with hydroquinones and ascorbic acid.46 Several complex ions of cobalt, for example [Co(NH3)5OH2]3+, [CoC1(NH3)5]2+ and [Co(en)3]3+, are development accelerators.47... 

Alkaline fixer (8.5-9.5) fine grain developers, baking soda... 

Borax is the mildest common alkali. It finds its widest use in low-contrast and fine-grain developers. Decahydrate is the preferred form. Sodium sulfite, though most often used as a preservative, can also be used as a mild alkali. In Kodak D-23 it serves both purposes. 

A good fine-grain developer is considered to be one that yields fine grain without any serious loss of speed. Fine-grain developers should be compensating, that is, they should prevent the formation of heavy, unprintable deposits in the highlight areas. 

When exposed silver halides are reduced to metallic silver via the development process, there is always a degree of extraneous, unexposed silver halide that remains attached. Fine grain and superfine grain developers make use of solvents to dissolve as much of the extraneous silver halide as possible. The more efficient the solvent action of the developer, the finer the grain. 

Glycin, used in combination with ppd (Formulas Superfine-Grain Developers DuPont No. 3 Superfine-Grain Developer), makes a fine-grain developer with improved emulsion speed and faster rate of development. Unfortunately, because of the presence of ppd, it still suffers from the unpleasant side effects of high toxicity and staining. 

As far as the general composition of superfine grain developers, nearly all of them have a high sodium sulfite content as sodium sulfite is an effective silver solvent. For an alkali, they use small quantities of either carbonate or borax in order to minimize the energy of the developer and produce a finer grain. FX 10 uses a buffering mixture of borax and boric acid, whereas Windisch Superfine Grain Developer uses sodium metabisulfite to reduce the pH of the sodium sulfite. 

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. 

Uses As a mild alkali accelerator in fine-grain developers and those of low activity in certain hardening fixing baths and in some acid hardeners, especially those intended for prints that are to be dried through heated belt driers and in gold toning baths to render them alkaline and to increase the rate of deposition of gold. 

Until the advent of 35 mm film, with the resulting emphasis on fine-grain developers, glycin was used mainly in paper developers. Now it is sometimes used in combination with other developing agents for fine-grain film development. 

The use of caustic alkali (e.g., sodium hydroxide) is not recommended with metol as there is a tendency to excessive fog. When used with sulfite alone, without additional alkali (Kodak D-23), metol provides a slow-working, fine-grain developer. This type of film developer often works well with a mild alkali, such as borax, which accelerates the rate of development without increasing the grain size appreciably (Kodak D-25). 

Notes p-Phenylenediamine is the classic superfine-grain developer. Besides the cautions that follow, it requires strong overexposure of the film and a very long developing time, often twenty minutes or more, and even then the contrast of the resulting negatives is rather low. 

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