Jest jeszcze jedna metoda i zdaje mi się że w fabrycznych wywoływaczach stosowana. W książce The Darkroom Cookbook na stronie 186 podana jest informacja jak rozpuszczać fenidon:rbit9n pisze:ja chyba znalazłem przyczynę osadu w moim id78. otóż ostatnio kupiłem filtry wiodącej marki, które są tak podłej jakości, że po tygodniu czajnik zarasta kamieniem. będę jeszcze badał ten trop, bo osad jaki się wytrącił słabo mi wygląda na fenidon, a raczej na węglan wapnia.
ale metoda z izopropanolem bardzo obiecująca w sumie.
Notes: Phenidone is sparingly soluble in cold water and moderately in hot and can require temperatures of 175F/80C to dissolve. It is readily soluble in both aqueous acids and alkali, including solutions of alkali bisulfites and carbonates, so that it can easily be incorporated into a developer solution. Used alone in sodium carbonate/sulfite solutions, it is very fast but extremely soft working and is only capable of producing negatives of low contrast. In combination with hydroquinone it produces developers with superadditivity that are even more effi cient than MQ developers.
Phenidone-based developers keep better than those based on metol. The reason is the oxidation product of Phenidone is more efficiently regenerated by hydroquinone than is metol.
Additionally, while the first oxidation product of hydroquinone, mono-sulphonate, forms an almost inert system with metol, it has a superadditive effect with Phenidone, increasing developing power. Because very small amounts of Phenidone are required, it is often desirable to use a percent age solution.
A concentrate of Phenidone, containing a preservative, can be made as follows:
Water at 125F/52C, 750.0 ml
Sodium bisulfite, 6.0 g
Phenidone, 2.0 g
Cold water to make 1.0 liter
100.0 ml of the concentrate contains 0.2 grams of Phenidone.
The preservative will have no appreciable effect on any developing formula. Alternately, a 5% concentration can be made using methyl hydrate instead of water, but it does not keep.