Hello, I have looked around in various forums. As a tip from me: the company Supergrip does something like that. I am a tiler and my tile supplier delivered the wrong tile to me. However, they are already installed and we only noticed the mistake after installation. After stumbling upon this company during my search, I called them directly and asked if they could help me. Two days later, two employees were on site and treated the tiles afterward, so that they now have the desired slip resistance. I am super impressed with them and their product. So if anyone here still has problems with their tiles not being slip-resistant enough, just contact them. Excellent advice and service. The price is also reasonable. Of course, I will bill my supplier for this service. ;-)