Developing agents negative

As a developing agent, catechol tans the surface gelatin of the negative (see Tanning Developers, below). It is also easy to use catechol to compound formulas that create a desirable image stain density when low quantities of preservative (e.g., sodium sulfite) are used (see Image Stain, below). Both of these properties it shares in common with pyro. 

Uses As a preservative of developing agents constituent of the acid fixing bath blackener in negative intensification active energizer in amidol development. 

If the development rate by negatively charged developing agent ions is monitored until all the silver halide is reduced, it follows a typical S-shaped curve that has been interpreted as a consequence of autocatalysis caused by the increasing surface area of the developed silver. An alternative interpretation by Gavrik [23] holds that this autocatalysis is a consequence of simpler kinetics and that development is better represented by simple relations where developed silver mass is proportional to development time with an initial induction period and a final exhaustion period when all the silver halide has been reduced. Levenson [24], however, has reaffirmed the autocatalytic view. 

Early in Section 1.2.2 it was shown that if the potential of a developing agent is more negative than the silver ion potential, then development or silver ion reduction is thermodynamically possible. The difference between the equilibrium silver potential and the developer or redox buffer potential Ejev is ... 

During development, exposed crystals are chemically reduced to Ag much more rapidly than nonexposed crystals, while the developing agent is oxidized. Since more silver is usually produced at exposed crystals, typical b/w development is negative-working. Dye image formation, which is necessary for color photography, depends on the... 

Fig. 24. Representative cross-linking systems employed in negative tone CA resists, (a) Epoxy polymers requiring organic solvent development, (b) PHOST-based cross-linking systems requiring aqueous development, (c) Monomeric cross-linking agents used in PHOST matrix polymers.

Flame-Retardant Treatments For Wool. Although wool is regarded as a naturally flame-resistant fiber, for certain appHcations, such as use in aircraft, it is necessary to meet more stringent requirements. The Zirpro process, developed for this purpose (122,123), is based on the exhaustion of negatively charged zirconium and titanium complexes on wool fiber under acidic conditions. Specific agents used for this purpose are potassium hexafluoro zirconate [16923-95-8] [16923-95-8] K ZrF, and potassium hexafluoro titanate [16919-27-0], K TiF. Various modifications of this process have been... 

Lesser amounts of sodium thiocyanate are used in color toning photographic paper, as a stabilizer in rapid film development, and as a sensitizing agent in color negative-film emulsions. It is also used as a brightener in copper electroplating. 

A negative attribute of orthophosphate is its tendency to precipitate with calcium hardness found ia natural waters. In recent years, deposit control agents that prevent this deposition have been developed. Owiag to its relatively low cost, orthophosphate is widely used as an iadustrial corrosion inhibitor. 

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