How do you prepare corner beads for the plaster finish coat?
This question is asked often. The success of having the finished plaster look “right” - with either a smooth or textured finish, has much to do with how the base coat is applied and worked with on the corner beads. Most of the time I inspect homes I find that the beads were simply filled out with base coat and then the finish coat was applied over this.
With the base coat even with the corner bead, there is no place left for the finish coat. With smooth coat it is applied and often gives the appearance of being overfilled or bulged slightly. With texture it will hang over the edges and just give a bad appearance to the bead instead of one that is nice and neat.
The solution lies in rodding off some of the base coat after the corner bead is filled out. Many plasterers I know use a cedar shake that has the edge sanded to a nice rounded finish on the edge. This is wet down and pulled up the corner, keeping the shake almost parallel to the wall as it’s used to rod off some of the base coat. Some will put a small notch in the board where the bead can ride as they do the rodding. Others slide it back and forth as they rod up the bead. The whole idea here is to keep the base coat uniform and to leave a small amount of space that the finish coat can fill in.
Thanks again for sending in the question, and keep them coming my way! W&C
Robin is a 20-year veteran of the plastering trade and has produced a series of videos on the subject. Write to the Plaster Man, Walls & Ceilings, 2401 W. Big Beaver, Suite 700, Troy, Mich. 48084.