An Unsolvable But Not Too Serious Problem

I’ve probably mentioned this issue before, but in September 2025 I came across the perfect illustration of it, so here we go: That’s an 1860 commercial building designed by John Kellum, one of New York’s better mid-1800s architects. I’m reasonably sure that’s Tuckahoe marble veneer, both because of its appearance and because that was a popular white stone of that era in New York. A fair amount of ornament was recently replaced as part of a renovation, and the new stone looks to have been carved as good matches for the damaged material it replaced. The old stone is dirty. Close to a hundred years of coal smoke from building boilers, and a different hundred years of automobile exhaust, can do that. And Tuckahoe marble is porous and has, as it weathers, a rough surface. There is no requirement for people to clean the facades of their buildings, and it’s unlikely it would matter if there were: I believe the light yellowish-tan areas between the second floor windows are where stone was…