Re-lathing and Plastering the Mansion
Similar to the flooring, an amazing amount of Madison-era riven lath survived. Riven lath, which are thin wooden strips split from four foot long oak or pine timbers, is used to hold the plaster onto the walls. Each lath is attached to the wooden framing elements with a gap left between them to accept the plaster. Where the original riven lath did not survive, usually because the duPonts had removed the original wall, historic riven lath from other sites was installed.
After the lath is installed, the masons will begin to plaster. Plaster during President Madison’s time usually consisted of two or three coats of a mixture of lime and sand. After plastering, the walls will either be lime washed or, if evidence of wallpaper has been found, papered.
Images of the Re-lathing and Plastering
Masons re-securing ca. 1797 lath in one of the upstairs bedrooms.
A mason lathing the ceiling of one of the second floor chambers. The lath, thin wooden strips use to attach plaster to ceilings and frame partitions, is the first step in the plastering process.
Applying scratch coat to the ceiling of the colonnade.
One of the ca. 1765 upstairs bedrooms with after the base, or scratch, coat was installed. A traditional plaster finish has two or three coats of plaster. The first coat is often called the scratch coat due to the grooves that the plasters "scratch" into the surface of the plaster. The second coat, which was only applied in the finer, higher status spaces, was called a brown coat. The final layer of plaster, which was often made from a mix very rich in lime, was called the white coat after the color of the lime.
What is Lath?
The Art & Architecture Thesaurus defines lath as the surface, other than masonry, to which plaster is applied. Lath is made from various materials, including expanded metal mesh, gypsum board, or other material that will sufficiently bond the plaster.