Have been sanding a 30-year-old chimney indoors, would like a smooth and even surface. It seems like it has been plastered with some kind of lime mortar, as it is completely white and dusty! However, need to add more plaster in some places, but don't know which product is easiest to use? Hydraulic lime mortar, kc-mortar, or ordinary lime mortar? Which is easiest to work with?:S
