I live in Pittsburgh in a house from the 1940s and scars from the pre-1980s steel mill pollution remain on my exterior sandstone wall.
I pressure washed with an ~1,800 psig pressure washer that only removed some surface dirt.
I then used muriatic acid at 1:8 dilution: wet the stone, applied with acid brush, let it ist for ~8-10 minutes and pressure washed. That cleaned some of the stones, but left some of the stones splotchy with areas that are bleached, some that are now clean and other areas that remain black.
I'm considering:
1. Repeating the muriatic acid
2. Renting a more powerful pressure washer.
Any advice? Many thanks, Brian
I pressure washed with an ~1,800 psig pressure washer that only removed some surface dirt.
I then used muriatic acid at 1:8 dilution: wet the stone, applied with acid brush, let it ist for ~8-10 minutes and pressure washed. That cleaned some of the stones, but left some of the stones splotchy with areas that are bleached, some that are now clean and other areas that remain black.
I'm considering:
1. Repeating the muriatic acid
2. Renting a more powerful pressure washer.
Any advice? Many thanks, Brian
