Q.: I recently read a specification that required a "burnished" slab. I'm not familiar with this slab type. Do you know what the spec is asking for?
A.: Burnish refers to the finish. A burnished finish requires troweling the slab to the point where it appears very smooth and glossy. According to concrete floor consultant Carl Bimel, this type of finish requires two or more trowelings. The trick, according to Bimel, is to time the last pass so that you can use a high angle on the trowel to produce a very tight surface. The result is similar to a trowel-burned surface, except that trowel burning darkens a slab while burnishing makes an extremely hard, tight surface. Subsequent curing and sealing enhance a burnished slab's glossy surface.