Silver halide developing solutions
AssigneeIlford Limited
InventorRoss Fielding
Life of this patent
Estimating the term…
Abstract
There is described a concentrated developer solution which comprises from about 20 to about 60 g/l of dihydroxybenzene developing agent, preferably hydroquinone, from about 0.5 to about 3.0 g/l of an auxiliary developing agent, preferably 1-phenyl-3 pyrazolidinone, from about 300 to about 500 g/l of potassium sulphite and which is buffered to a pH of from about 8 to about 10 with a buffering agent other than an alkanolamine and which comprises sufficient organic solvent other than an alkanolamine to dissolve the hydroquinone. Such a concentrated developing solution which contains a high concentration of potassium sulphite has when diluted a long useful life and produces images of low graininess.
Claims12
A concentrated developer solution which comprises from about 20 to about 60 g/l of a dihydroxybenzene, from about 0.5 to about 3.0 g/l of an auxiliary developing agent, from about 300 to about 500 g/l of potassium sulphite and which is buffered to a pH of from about 8 to about 10 with a buffering agent other than an alkanolamine and which comprises an organic solvent other than an alkanolamine sufficient to dissolve the dihydroxybenzene.
Dependencies are inferred from the claim text.