"Clinker" bricks are bricks that were exposed to intense heat when fired which gives them a dark, varied appearance and irregular shape. They make a metallic sound when banged together, which is why we call them clinkers. They are an old style brick that you see in old houses and we always do our best to preserve them in in our jobs. The top third of this old chimney was coming loose and needed to be rebuilt. After careful cleaning the bricks for reuse we rebuilt the chimney with rebar supports, wire mesh and mortar. A beautiful classic Berkeley chimney ready to ride out another 100 years on the Hayward fault!