Dyeing auxiliary

A process for dyeing blends of elastane and natural or synthetic polyamide or cellulose fibres which comprises treating said fibres with an aqueous liquor consisting of

• (a) a betaine of formula
• wherein R1 is a monovalent radical of an aliphatic C4-C30 hydrocarbon,
• R2 and R3 independently of one another represent C1-C12 alkyl and
• X and Y independently of one another denote a bivalent radical of an aliphatic C1-C12 hydrocarbon,
• (b) a quaternary ammonium salt of formula (2)
• wherein R4 is a monovalent radical of an aliphatic C4-C30 hydrocarbon,
• R5, R6 and R7 independently of one another represent C1-C12 alkyl, C5-C24 aryl or C6-C30 aralkyl,
• A− is halogenide, nitrate, hydrogensulfate or sulfonate, and
• (c) an alkoxylated fatty alcohol,
• and (d) at least one dye and optionally
• one or more additives selected from a alkali, lubricant, electrolyte, antifoam, flame retardant, dirt-repellent, water-repellent, oil-repellent, alginate and water,
• and wherein the process is carried out in accordance with a padding or exhaust process.