I have to remove grout in a bathroom black slate cladding wall. The contractor (who apparently didn't know much about porous stone tiles) has tried too many things, grout removed, vinegar, hand scrubbing, etc. and nothing is really working... :( I am getting ready to try power washing, carefully and with a small nozzle to not remove much of the in-between grout from the wall. Anyone feels strongly against it?
I will report back results afterwards...
[![Wall zoomed in][2]](../../images/bcafc18ff5ca71f1f06fd6adbcb566d0.webp)
[![With original tile for comp][3]](../../images/f6768f158d3e9d28f3f9fec88e00f0c5.webp)
