The invention relates to an aqueous dye solution comprising a) 5 to 30% by weight of an anionic or cationic direct dye, b) 0.1 to 10% by weight of 1-phenoxy-2-propanol, c) 0 to 20% by weight of an inorganic or an organic acid, d) 0 to 20% by weight of further additives and e) water to complete to 100%, a process for the preparation of the solution and the use thereof for dyeing paper.