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Antique plaster and how to restore it

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Let’s get plastered!

Left: A variety of plaster wall panels. Right: The clay prototype for a ceiling decoration.
Photos by Robert Khederian

Welcome back to Period Dramas, a weekly column that alternates between rounding up historic homes on the market and answering questions we’ve always had about older structures.

Last summer, we took a day trip to check out an early 19th-century Federal house that was on the market about an hour and a half north of New York City.

The house had essentially sat vacant for a few decades and was previously inhabited by somebody who did very little work on the house. In short: Very little had changed since it was completed in about 1830. It needed an alarming amount of work.

We immediately noticed the house’s plaster walls and molding. We began to think about the wide spectrum of places we’ve seen plaster detailing—from social clubs’ stately drawing rooms to picture molding in our own (modest) apartments. And now here we were, about a hundred miles north of New York City, confronting a similar type of construction.

If we were to take on the restoration, what does rehabilitating—or replacing—plaster take?

The house’s master bedroom. Notice the section of molding that’s missing above the fireplace.

“In the 19th and early 20th centuries, the plaster industry was thriving,” says Foster Reeve, founder of Foster Reeve & Associates, an architectural and ornamental plaster company. “That was how you built. You didn’t have the dimensional lumber that you have today. There was essentially just lathe and plaster.”

“Today, you often find people working with joint compound and sheetrock,” Reeve says. “That can be washed right off a wall, whereas one coat of veneer plaster is stable, and durable—it’s practically bulletproof.”

The main hallway on the second floor has plaster walls that have very noticeable cracks.

The plaster walls and moldings are married together to create a monolithic surface. Don’t think you can just take down plaster molding; If you want to remove it, chances are the wall will come with it, too.

Reeve went on to explain that the traditional method of installing plaster moldings—a process called “running”—is an involved, multi-step process. As opposed to wood moldings, which are first carved and then installed, plaster moldings are formed on location, in the specific place where the molding is desired.

“First you need to [apply] wire mesh, followed by a brown coat, which is essentially a primer layer,” he says. “Then you set your tracks—the line that the molding is going to follow. It’s very important to get that straight, or else the look of the molding will be off. Sometimes that involves squaring up the wall if it’s crooked.”

A tool with the profile of the molding is then used to push and form the plaster. The plasterer is usually working overhead—if we’re talking about crown molding—with a material called “fat lime,” which is so acidic that it can splatter and burn whatever it touches.

Only a short section of molding can be run at once, Reeve explained, and meeting two tracts of molding in a corner requires a different set of tools and expertise. “If you ever are looking at molding and wonder why things may start to get wonky as it turns into a corner, that’s why.”

While running plaster molding typically happened on location, Reeve has evolved further, moving the process to his loft-like warehouse in Brooklyn’s Greenpoint neighborhood.

There, he works to run moldings according to measurements and specifications that he and his team take on site. The moldings are run and then hung to dry out for about a day in what Reeve calls the “sauna.” Then, they’re taken and installed on site in a process that preserves the monolithic quality of traditional plaster construction while minimizing mess.

But these relatively simple molding profiles are just a fraction of what Reeve creates in his workshop.

Always referencing historic precedent—which is unsurprising, since he’s an active member of the Institute of Classical Architecture & Art and a custodian of many 19th-century plaster casts from the Metropolitan Museum of Fine Art—he creates everything from ornate wall panels to intricate ceiling designs.

“A client restoring a house in the Hudson River Valley recently came to me asking for help. I immediately said ‘Great! Let’s open some books and find inspiration!’” says Reeve.

The process for creating these intricate designs involves first sculpting them out of clay, then making a mold from the clay program. The plaster is then cast into the mold before drying out in the sauna.

But thankfully, the plasterwork that originally inspired our curiosity didn’t require such an ordeal to repair. “If I were to restore this, I would take a bit of the existing molding to replicate the profile and then run just what needs to be repaired,” says Reeve. “And then it’s up to whoever is painting it to make the repair look seamless.”