Before a fresco can be painted, the wall surface needs to be prepared to take the plaster. The St Seraphim church is block and concrete, so, we decided to first attach metal studds to the block or concrete, and thus build it out a bit to add to insulation and keep the paintings that will eventually be in those places away from an outside wall. We then paper the wall surface with a water-proof material, such as Tyvek, and then attach metal lathe (looks like chicken wire) to the studds. After the steel work has been completed, then the first coat of plaster is applied. This coat is called the scratch coat, since it is very deeply scratched. The scratched surface will be part of the all-important bond for the next plaster coat, the brown coat, which is smooth. Once the brown coat has been applied and it dries, the fresco painters can apply their painting coat, a lime putty mixture, on to which they paint directly, using only ground pigment and water. For a thorough discussion of the plaster technique, see the following website: http://www.gsinai.com/rw/icons/fresco_in_a_church.php.