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-3piece-wall-mixer/HG103031800AXOR Concealed Part For 3-Piece Wall Mixer//www.cphart.co.uk//images/products/medium/HG103031800.jpg202.50270.00GBPInStock/basin-taps/HG103031800