The invention relates to a process for the purification of a melamine condensation product, comprising the steps of a) making a diluted slurry of a reaction product mixture comprising the melamine condensation product in a solution of a base in water with a pH of at least 9, b) keeping the diluted slurry for a period of at least 1 hour, c) concentrating the diluted slurry, thereby obtaining a concentrated slurry and an eluent, and d) washing the concentrated slurry by diluting the concentrated slurry with aqueous liquid and repeating step c, wherein the washing is performed by counterflow washing wherein eluents of downstream concentration steps are used to wash the slurry in upstream concentration steps.