DE1958875

Surfaces, esp. printed circuits built up with components which are covered after soldering with a flux layer based on resin or collophony. In which decomposition products and metal salts caused by the soldering are embedded, are cleaned by dissolving the layer in a wash liquid whereby the decomposition products and salts form stable colloids in folution, which is then diluted with the wash liquid. The preferred wash liquids consist of (1) organic compounds e.g. a mixture of toluene and n-butyl acetate which dissolve the layer and have lyophobic character towards the colloids present; (2) an organic solvent e.g. isopropanol in a volume which maintains the lyophobic character; (3) an organic solvent e.g. 1,1,2-trichloro-1,2,2-trifluoroethane miscible with (1) and dissolving the non-collloidal material but maintaining the lyophobic character.