A vacuum treatment apparatus and method for manufacturing has a plurality of treatment chambers for treating workpieces, in particular silicon wafers, a transfer chamber attached to the treatment chambers communicating via respective openings and having handling zones located adjacent to each of the treatment chambers. The light source apparatus body includes a connector that electrically connects the light source apparatus body to a light source driver. To clean off mixture 50 stuck to the whisk 46 the whisk wiper 30 is simply pulled off, the opposed edges of each slit 32 wiping the loops 44 clean, the removed mixture 50 collected on the top side of the whisk wiper 30 so it can be then returned to the mixing bowl 52.