The present invention relates to a process for the production of an aluminium multilayer brazing sheet which comprises a core layer made of a 3xxx alloy comprising 0.1 to 0.25 wt. % Mg, a brazing layer made of a 4xxx alloy on one or both sides of the core layer, and optionally an interlayer between the core layer and the brazing layer on one or both sides of the core layer, the process comprising the successive steps of:



providing the layers to be assembled or simultaneous casting of the layers to obtain a sandwich;
rolling of the resulting sandwich to obtain a sheet; and
treating the surface of the sheet with an alkaline or acidic etchant.