In a moment of madness I had "stone tiles" put on the floor and walls of the bathroom.The shower tray is a pre-formed composite material that is tiled.. The mastic pealed around the junction between the wall and floor of the shower (it's all covered in tiles, no plastic tray) causing a hard to diagnose water leak. When pulled, the mastic pealed off the tiles like opening a new zip. Is there a good "sanitary" sealant (what does that mean anyway?) that has good adhesion to stone tiles? Should I prep the area where I am going to reapply mastic in any way apart from leaving it all to dry out for a couple of weeks? Does dilute bleach cause mastic to fail which I use when there is a hint of mould on the mastic?

Thanks,

Clive