Anyone who has restored original plaster walls is familiar with three-coat plaster: a scratch coat over wood or metal lath, a brown coat, and a top coat. As for historically correct surface finishes, things go beyond one, two, three. Matte and high-sheen finishes—including some that are waterproof—along with textural effects have been in use for centuries and are especially relevant today. Plus: Have you heard of earthen finishes for floors? • Whether you’re a novice or a pro, patching or matching a historic plaster finish can be tricky. That’s because the composition of the plaster found in American homes has continually evolved as available materials changed and innovations were developed. • Determining what components are in a 180-year-old plaster, for example, requires a bit of detective work. Most plasters that old will necessarily contain sand and lime, but the proportions of each component, where they come from, and even how the lime is produced all make a difference in the finished surface.
“You want to replace like materials with like materials,” says Joelle Huntsberry, who has restored plaster and other surfaces at historic sites including Montpelier and Historic Jamestown, near her Virginia home. It may mean adding lime made from local oyster shells to the mix—or adding
