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-exafill-s-concealed-part-for-large-baths/HG58116180hansgrohe Exafill S Concealed Part For Large Baths//www.cphart.co.uk//images/products/medium/HG58116180.jpg164.01164.01GBPInStock/bath/HG58116180