It is stainless, and my understanding is that it is high quality. That's why I'm thinking its an issue of the sandpaper having left bits of material which then fanned out as I burnished. I am sanding it; have gone over the wall with 200-ish grit and will work my way up to 1500 and will then buff. Then I'll go over the whole thing with pigmented wax. But I need to figure this out for the other three walls; yikes, I dont want to go through this sanding again...