Monday, April 5, 2010

Scratch coat applied

The fresco crew, Pam, Nick, DePaul, Nate. Others not shown in this photo: , Theresa and Mike.

Over the weekend we applied the scratch coat to the wall. This gray layer gets its color from the gray Portland cement that is added for strength. To ensure the "key" gets a good grip the coat is applied to the wall without using finishing techniques such as screeding or floating. After this thick layers sits for a short time (30 min) it is "scratched" with a plasterer's comb. Care is taken to to scratch deep enough to provide tooth for the subsequent layers, but not so deep that it could sever and weaken the coat's strength. Due to the addition of the cement, repeated wetting of the wall is required for two days to prevent cracking.

The next layer commonly called the stabilizing layer or leveling layer will be meticulously worked to even out the lumpy scratch coat. A more comprehensive tutorial on the methods and materials used will be coming soon at