The exposed limestone between our front foyer and kitchen was formerly an exterior wall. At one point, our plan was to demo this wall to open up the kitchen, and use the stone to restore the northeast section of the house that had burnt down roughly a century ago. However, in April 2017 when general demo began and we pulled off the plaster that covered those walls, our plan quickly changed.
Three main things led us to reconsider demolishing this wall. We were very pleased to see how well the mortar had held up; minimal re-pointing will be needed. Second, once the flat ceiling was removed in our master bedroom, we were awestruck by the look and feel of the stone wall and vaulted ceiling. Third, we loved the breathtaking color and character of the now-exposed well-preserved limestone up in the attic area.
We worked with the contractor to revert to an earlier plan that included the wall, and made designs to keep the vaulted ceiling in the bedroom. The big remaining problem, though, was that most of the limestone was still coated with a thick layer of plaster and dirt. Our contractor quoted us a price to clean them with sandblasting, but it was steep and out of our budget. We would have to do this one ourselves.
Seeking to do as little harm to the limestone as possible, we started with just elbow grease. With non-wire scrubbing pads and neutral cleaning agents, we scrubbed. And scrubbed. We had to use minimal water so as not to damage the floors. It made a difference, but a good bit of the plaster was just too stubborn. The walls still needed work.
We then moved to low-psi abrasive blasting using a portable air compressor and a siphon-fed blaster hose that proved to be $20 very well spent. We tested on surplus limestone to find the right pressure and distance that would not eat away the stone itself, then set to work. It was a long, tedious process, especially taking care to preserve the mortar. I can see why the contractors charged so much.
We are very pleased with the result. Once overall construction is drawing to a close, we will give the walls another good scrubbing, then apply some sort of (non-sealing) finish.