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PMK PYRO

 PMK Pyro Formula: Stock A: Distilled water, 100 deg F, 750 ml. Metol 10 g Sodium Bisulfite 20 g Pyrogallol 100 g WTM 1 L Stock B: Distilled water 1400 ml Kodalk ... [Prosegue]

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ROLLO PYRO

Ce poco da dire con le sviluppatrici automatiche ci si e accorti che il pyro non regge lagitazione continua evidentemente a contatto con laria assida troppo velocemente e perde lattivit224 dopo qualche minuto Per ovviare il problema e stata modificata la formula Stessi ingredienti ma con laggiunta dellacido ascorbico per prolungarne lattivit224 [Prosegue]

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FX-37

Geoffrey Crawley has formulated and dislosed FX 37 a developer optimized for both T-Max and Delta films Crawley makes it clear that FX 37 is not just for use with tabular grain films This black-and-white negative developer is proposed for the processing of modern films especially those using so-termed high-emulsion technology such as T-Max and Delta But it may be used for traditional type emulsions when the finest grain is not the prime requirement It is an independent formula not a substitute for any commercial product FX 37 is designed to produce enlarging quality very sharp tonally rich negatives on modern films with an EI speed increase It is not a fine grain developer in the sense and assumes that the fastest films will not be used when big [more than 12x] magnifications are required FX 37 fully exploits Phenidones speed enhancing properties For most films true speed is a half to two-thirds of a stop more than the manufacturers ISO [Prosegue]

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CONTROLLING PRINT IMAGE TONE

Two main factors control the color or image tone in a black-and-white print The first is the type of paper and its halide composition meaning how much silver bromide and silver chloride it contains Although the terms bromide and chlorobromide are terribly unscientific and misleading they do suggest something about the general halide mix in a black-and-white paper These days all papers contain a mix of bromide and chloride but generally speaking a bromide paper has less silver chloride than a chlorobromide paper Keep in mind that its altogether possible for Brand Xs bromide paper to have more silver chloride than Brand Ys chlorobromide Bromide papers tend to be faster and produce colder or more neutral tones Socalled bromide papers are the mainstays of general black-and-white printing Papers called chlorobromide by manufacturers tend to be slower and yield warmer image tones Many people like the look of a chlorobromide print over a colder bromide type These slower papers are also more flexible in that they respond more readily to image tone manipulations produced by developer modifications Chlorobromide are best suited for neutral to cool print tones Amidol is considered as the classic developing agent for creating cold tones on bromide papers Cooler color is best obtained with print toners Neutral and cold tones tend to create an emotional distance a sense of looking at the image from the outside Warm tones tend to engage the viewer emotionally drawing them to the image Learning to manipulate and control the tone of a print opens up new vistas and ways to communicate a photographer vision Whereas the tint is most easily seen in the highlights the tone of a print is most obvious in the shadows The developer is the second factor contributing to image tone A developer can foster either a warmer or colder tone depending on its composition Although developer composition exerts an enormous influence on overall image tone it turns out that most image tone effects can be controlled with just three ingredients bromide concentration organic restrainer (antifoggant) and type of developing (reducing) agent Cold tone developers can be used to produce very subtle cool tones on bromide papers Gold toning of normally warm chlorobromide papers is generally reconized to provide the most pleasing cool image tone Paper-Developing Agents Pyrocatchin: warm tones Glycin: neutral tones and subtle gradations Amidol: cold-tone formulas Manipulating The Print Image Tone Cold Tones MQ Developers Reduce the amount of bromide Reduce the amount of bromide and add benzotriazole PQ Developers Eliminate the bromide and replace it with 1 benzotriazole solution Increase the benzotriazole 1 solution up to 15 ml per liter of working solution Substitute Phenidone and benzotriazole for metol and bromide Neutral Tones Eliminate or reduce the amount of bromide andor substitute benzotriazole Warm Tones Reduce the amount of sodium carbonate Substitute potassium carbonate for sodium carbonate Increase the amount of potassium bromide using a 10 solution Increase the exposure and shorten the developing time Dilute fresh developer with up to 50 used developer Generally speaking increasing the bromide level in a developer leads to warmer tones whereas increasing the level of an organic antifoggant (eg benzotriazole) leads to colder tones Since PQ (phenidone -hydroquinone) developers generally contain an antifoggant they often produce colder tones than nominally equivalent MQ (metol -hydroquinone) types Developers containing the agents glycin or chlorohydroquinone produce warmer tones if organic restainers are ommited from the formulation These agents produce more neutral tones if an organic restrainer is included This suggests that you could devise a continuous-tone control scheme using a stock warm-tone glycin or chlorohydroquinone developer plus a stock solution of benzotriazole or 6-nitrobenzimidiazole etc The system would be calibrated for a particular print paper by adding varying drops of restainer to produce a given image tone Potassium bromide may be added as a restrainer It should usually be prepared as a 10 percent solution You might begin with about 50ml of a 10 solution of potassium bromide per liter of stock developer Check on the effect of the bromide and add more as necessary until you have the disired effect Examine the print in daylight if feasible for a more accurate color evaluation The bromide sometimes adds a slightly greenish tone to the image which can be overcome in most cases by selenium toning Benzotriazole (Kodak Anti-Fog 1) provides about the same restraining effect but produces a noticeable shift in print color toward the blue Use 25ml of a 1 solution of benzotriazole per liter of stock developer Adding 50 ml of the 1 solution causes a noticeable color shift toward the blue and with 100ml the effective paper speed by roughly two-thirds of a stop Increased amounts of benzotriazole seem to affect the image contrast somewhat more so than potassium bromide but this effect may depend on the paper and developer used The use of both of these chemicals effectively reduces the speed of the papers and thus requires an increase in exposure They may also lengthen the emergence time of the image in the developer and some papers may therefor require lower than normal development factors With contemporary papers benzotriazole will cause a distinct cooling of the image color and potassium bromide will increase its warmth Based on the solubilities of the silver salts 10gliter of Potassium bromide is roughly equivalant to 02gliter of Benzotriazole (Anti-Fog1) [Prosegue]

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F24 FIXER

Fixer 24 is a nonhardening sodium thiosulfate fixer which is recommended for prints Hardening is neither necessary nor desirable when fixing prints Without hardening both hypo and the other developing by-products will wash out of the gelatin readily In addition a nonhardened print is easy to tone and spot While Fixer 24 will fix film its nonhardening action will result in a negative whose wet emulsion is delicate and easily damaged [Prosegue]

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