So recently we tackled this limestone shower stall which was in pretty rough shape.
Step one was to deep clean all the surfaces, the tiles, the grout, the glass and hardware. A special natural stone-safe cleaning solution was applied and scrubbed followed by our indoor vacuum-contained hot water pressure washing system. This is 1200 psi of hot water spinning jets blasted at the surfaces, all contained in a vacuum chamber so all the water and cleaning solutions are recovered and there's no mess spraying around outside the shower stall.
Step 2 - Repeat Step 1.
Step 3 - The tiles were treated with a heavy duty mould remover. This treatment was allowed to dwell on the surface for 20-30 minutes or so then the pressure washing process was repeated to rinse it all away.
Step 4 - The limestone tiles were then honed using diamond abrasives on a polishing machine to smooth out the badly etched and rough surface in order to prevent rapid re-soiling and for easier maintenance moving forward.
The glass was also polished using special abrasive creams designed for removing soap film and mineral deposits. After honing was complete and glass was polished, one final deep clean with the pressure washing system to remove any limestone slurry from the honing process and any glass polish splatter.
Step 5 - Some of the grout was cracked so in those areas the old grout was cut out and re-grouted. This was a minor repair but very important to keep moisture from getting in behind the tiles.
The shower was allowed to dry overnight.
Step 6 - The next day a final touch up clean a few spots with a neutral cleaner, final clean the glass with glass cleaner and microfiber, and buff the grout haze.
Step 7 - A penetrating stone sealer was applied to help reduce the absorption rate of this stone.
Limestone is very absorbent and while beautiful and visually interesting, not really the best choice for a low maintenance shower installation.
The home owners were pleased and we set them up with some good products and a maintenance plan they can manage themselves and of course we're always here to help when things get out of hand again.