I plan on building a wall to be flush with the brick facing on my existing fire place and then covering the entire wall in Venetian plaster. I am comfortable with wood working, but Venetian plaster is a whole different ball game. I am still debating if I should put something like wonderboard on top of the brick and then do the plaster or throw on the plaster directly over the bricks. The area of concern is the space between the bricks, will it the plaster shrink over time and show off the brick lines if I put plaster directly over the brick? The mantle will also be covered with the same Venetian plaster. Not sure if I should have a contrast color for the Mantle. May be someone has experience with Venetian Plaster and can advice me. Please see before picture and after rendering in my Gallery.