I have just used the HG Mould Remover on my shower as it says it's for use in bathrooms and on grout, sealant etc. However, it would probably have been safer to just napalm my shower. My white tiles, are somehow now even whiter in random places, and the product itself is so strong I think the first spray took a year off my life and reduced my lungs to jelly. Unless you are the kind of person who enjoys living on the edge, or are trained in chemical warfare, then give this a miss.