GB564271A - Improvements in concentrated photographic solutions - Google Patents

Abstract

564,271. Photographic hardening solutions. KODAK, Ltd. (Eastman Kodak Co., and Russell, H. D.). March 15, 1943, No. 4223. [Class 98 (ii)] A photographic hardening solution comprises at least 10 per cent by weight of an aluminium salt capable of hardening gelatine, e.g. aluminium chloride, bromide, sulphate, or nitrate, and at least 10 per cent by weight of a hydroxyaliphatic amine, e.g. mono-, di-, or tri-ethanolamine, 2-amino-butanol, #-diethylaminoethyl alcohol, 2 - amino - 2 - methyl - 1 - propanol, or 2 - amino - 2 - methyl - 1 : 3 - propanediol, or a cyclic derivative thereof such as morpholine. The amine should preferably be present to an extent of 20 per cent. The amount of water present should not be more than 40 per cent, and may be even less than 5 per cent. The water may be introduced by using hydrated compounds. The solution preferably contains acetate or propionate ions, and also a boron compound yielding boric acid such as boric acid itself, an alcohol such as methyl alcohol, ethyl alcohol, ethylene glycol, glycerol, diethylene glycol, triethylene glycol, or tetraethylene glycol, and compounds for preventing incrustation and precipitation, e.g. di- and tri-basic organic acids, citrates, tartrates, urea and glucono-d-lactone. If the solution is to be added to fixing baths; it should contain sufficient sulphur dioxide to prevent sulphurization. Sulphur dioxide may be introduced into the solution. Examples of various compositions, all containing aluminium chloride, are given. The fixing solution may comprise a hypo solution containing sodium bisulphite, or the fixing agent may be ethanolamine, ethylenediamine, guanidine, potassium, or ammonium thiosulphate. The rate of fixation may be increased by addition of the hardener.