Ready-to-use solution caustic soda lye / NaOH 2.0 mol/l (~ 8 %) for use in histology and/or cytology for differentiation / pickling / bluing or cleaning. As macro-etchant for aluminium welding seams (aluminium alloy/ pure aluminium/ hard aluminium alloys) in materialography. For macroscopic weld seam assessment. Provides a high-contrast image of the individual weld layers and heat-affected zones.