Patent ID: 6998227

Claim:
An aqueous, homogeneous, single-part color developing concentrate having a pH of from about 9 to about 13 and comprising: a) from about 0.05 to about 0.35 mol/l of an N,N-dialkyl-p-phenylenediamine color developing agent in free base form, b) from about 0.01 to about 0.5 mol/l of an organic antioxidant composition for said color developing agent that comprises an N,N-dialkyl- or N,N-diarylhydroxylamine derivative, and c) a water-miscible or water-soluble organic co-solvent that has a molecular weight of from about 100 to about 400, is present in said concentrate at a concentration such that the weight ratio of water to said organic co-solvent is from about 1:1 to about 3:1, and d) from about 0.002 to about 0.25 mol/l of a quaternary ammonium salt that is tetramethyl ammonium chloride, tetraethyl ammonium chloride, tetra-n-propyl ammonium, chloride, tetra-n-butyl ammonium chloride, ethyltrimethyl ammonium chloride, n-propyltrimethyl ammonium chloride, n-butyltrimethyl ammonium chloride, 2-hydroxy-ethyltrimethyl ammonium chloride, or a mixture thereof.