Blitz That Mould Brush-On Mould Remover Gel 250ml 1 "Disappointing" Mrs Sunderland 19 April 2018 Tried it on paint and sealant and window edges. Didn't work, despite leaving on for at least 30 minutes. I've tried repeatedly with this gel but I just don't get on with it. I've gone back to my usual spray bottle product that I know works, and works instantly. A note from the team Thank you for placing your review. I'm sorry this product was not successful in removing the mould. From personal experience I leave it in place a couple of hours and find it works wonders. I trust you've found an alternative that suits you better.