This part of ISO 9455 specifies a method for the de-termination of the zinc content of water soluble fluxes of type 3, as defined in ISO 9454-1. The method is intended to apply to an aqueous solution of flux containing approximately 25 % of zinc, ex-pressed as zinc chloride (ZnCI2). For solid fluxes and for solutions whose concentrations differ ap-preciably from those stated above, an appropriate adjustment should be made to the amount of sample taken for the test.