Clean with warm soapy water followed by rinsing with clean water and drying with a soft cloth. All finishes are vulnerable to acid attack and some strong substances such as household cleaners or disinfectants can cause surfaces to go black or peel.
https://www.cphart.co.uk/hansgrohe-concealed-part-for-2piece-bath-filler/ZHG13550180hansgrohe Concealed Part For 2-Piece Bath Filler//www.cphart.co.uk//images/products/medium/ZHG13550180.jpg637.00910.00GBPInStock/tap-ancillaries/ZHG13550180