Scagliola: Beautiful Faker

By B. Gunar Gruenke
Published in Painting and Wallcovering Contractors magazine

Psst: Can you keep a 2,000-year-old secret? Some of the world’s most exquisite marble masterpieces…are not marble at all.

They’re not painted, either. They are, in fact, fabulous fakes – a hand-crafted imitation marble known as scagliola (skag-lee-OH-luh).

Never heard of it? That’s not surprising. Although beloved by its artisans since ancient times, scagliola has largely remained a mystery outside the decorative-arts realm.

No more. Lustrous, durable and versatile, scagliola is fast becoming a high-end favorite.

From vases to staircases, and columns to countertops, these beautiful blends of pigment and plaster are assuming forms and functions unavailable even to their stone-age ancestors.
Storied history
The first examples of scagliola were created in Roman times from selenite (SELL-en-ite), which derives from a gypsum stone found in Italy’s Appennine Mountains. Italian monks honed the technique in the 17th century; some of their creations survive today.

In the United States, scagliola was widely used from the mid-1800s to the 1930s, in the elaborate churches, capitol buildings and theaters of that era. In these applications, scagliola became a popular choice for large columns, wall cladding, pilasters and door surrounds.

The appeal (then, as now): The amount of marble demanded for such massive works would have been prohibitively expensive — if available at all. Scagliola looks like natural marble and is just as durable, but it is less expensive and can be formulated in a limitless range of colors and textures.
‘Polish and beauty’

“Painted marble can never be compared with scagliola, which has the look, color, touch and polish of the more costly natural marbles,” William Millar wrote more than a century ago in Plastering, Plain and Decorative.

“Experience has proved that it will last as long as the house it adorns, and with an occasional cleaning, it will always retain its polish and beauty.” 

It is those qualities – along with the renewed popularity of marble and its look-a-likes – that have refocused interest in scagliola.

Although less expensive than marble, scagliola projects are labor intensive and highly specialized. The finest results demand historical knowledge, technical excellence in fabricating the material, and the trained eye and hand of the decorative artist.

Projects may incorporate the traditional European technique, which uses lumps of a doughy mixture with mineral pigment for veining. More common, however, is the marezzo (muh-RET-zo) technique, which employs an almost-liquid mixture and raw silk fiber for veining.
American Marezzo 

Marezzo is sometimes known as American Marezzo because of its popularity in the United States. While the mixture varies for each installation, the process is similar.

First, precise molds of the object are created.  Next, a basic scagliola recipe is produced. This usually includes some combination of gypsum plaster, hydrostone, Keens cement, and mineral pigments to achieve the desired tint.

Artisans then work in the raw silk fiber to create veining and cast the doughy mixture into molds. Test batches are mixed, to achieve the correct colors and properties.

Once the scagliola has hardened, grinding and polishing begin. Hand polishing takes place over several weeks, using water and a fine grade of sandpaper. Finally, the surface is buffed with aluminum oxide and coated with a surface-enhancing sealant called carnauba wax for protection.

The finished scagliola is perfectly smooth, with a glossy sheen like that of the finest polished marble. 
Easy maintenance

If it is in good condition, scagliola requires minimal maintenance. In fact, cleaners or polishes should not be used, because they can cause discoloration. Carnauba wax on a dry cloth may be applied every two to three years for protection; the wax need not be applied to areas that are difficult to reach.

Scagliola that is in poor condition calls for more attention.  Stained or chipped areas must be restored by an experienced studio. Cleaning products on scagliola may cause discoloration and further damage.

The art of restoration

Restoring scagliola is an exacting process. Typically, it begins with an investigation to determine the condition, composition and original coatings on the material.

The surface is inspected for defects and documented with photos using specialized lighting. Information about the interior may be gained by attaching a fiber-optic lighted lens to a borescope video camera and recorder inserted through a 3/8” hole in the material.

These findings will help determine the scope of the work and the procedures to be used.

If the project involves tall columns or weight-bearing structures, the scagliola must be attached to rods or other inner supports to ensure structural integrity.

Next, old coatings are stripped from the scagliola, and test samples of the pigment are produced. Molds are created for larger patches and replacement pieces. After molding, the new scagliola sets for a few weeks before polishing begins.

Crafting repairs

Repairing cracked scagliola requires routing out the cracks to give them a rough V-shape that is optimal for adherence of the infill. The cracked and broken scagliola is patched and reinforced before the replicated pieces are installed.

As with restoration projects, scagliola must be anchored to inner supports; wire ties may be added for additional safety. Then, the scagliola is burnished and polished. The original and restored areas must achieve uniform color, texture and porosity. A non-yellowing sealer may be added for protection.

In the end, the repair should be undetectable.  Beautiful expanses of the deep, rich scagliola should shine with the glow of the original creation.
Project profile: French Lick

Scagliola played a major role in the recent $382 million historic restoration and expansion of French Lick Springs Resort in French Lick, Ind. Conrad Schmitt Studios, of New Berlin, Wis., was selected to restore the original decorative scheme of the 1845 resort.

Conrad Schmitt, founded in 1889, has restored and revived similar projects around the world. Its scagliola endeavors have included the Marquette County (Mich.) Courthouse; St. Louis (Mo.) Union Station; the Palace Theatre in Cleveland, Ohio; and the Cathedral of St. Helena in Helena, Mont.

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