Preservation Spotlight – Restoring Marezzo or “American Scagliola”

Introduction

G&H’s Preservation Studio is fortunate to find excellent examples of historic craftsmanship in our hometown of Richmond, Virginia. One such craft is demonstrated in the impressive scagliola plaster in the Jefferson Hotel’s Rotunda (see the mid-20th century postcard illustration above.)  While the dramatically veined marble columns have been discolored by years of use, they are otherwise in excellent condition. Examination of the room confirms that the columns in the Rotunda and in the other principal rooms, both from the original construction in 1893 and the rebuilding of the Rotunda in 1907, were not painted but executed using an updated and streamlined version of a decorative art form originally developed in Baroque-era Europe. This “modern” technique was known as “American” or “Marezzo” scagliola.  There are clear seams between the sections, and the veining patterns match those shown in early photographs.

Scagliola

The application of plaster to achieve a realistic marble finish was developed in post- Renaissance Tuscany as a substitute for expensive marble decorative finishes. It spread throughout the European continent with the explosion of finely detailed architecture in churches and palaces, and, with the growth of commerce in the nineteenth century, into a plethora of new building types. Integrally pigmented gypsum plaster with added animal glue to give strength and slow the hardening was used in molds and applied in situ to wall surfaces. Pigments and chips of marble could be added directly into the plaster mix to simulate by natural stone. The colors and contrasts were often more distinctive than those possible using natural stone. Veining was accomplished by drawing pigmented silk through the plaster or the plaster could be layered and sliced in different colors and cut back to give effect of marble. The spaces between small pats of about 3/8” in thickness are filled with a troweled slurry. The dry plaster was polished and buffed to achieve a hard, shiny appearance of stone. As master plaster craftsman Patrick Webb has observed, the complexity of scagliola requires highly developed skills:

“Through a series of slicing, addition of pigments, folding and re-joining the whole of the mass is mixed and set aside as large balls placed in ratios and arrangements that achieve the desired result: a counter-type of true marble or a fanciful creation. Depending on the desired outcome, from the initial mixing of colored slurries and other preparations are set aside for decorative effects. Much of the artisanship lies in a process of mental reverse engineering. One must conceive the desired outcome, have all materials on hand and systematically take steps to accomplish the effect” [Patrick Webb 2014].

Scagliola became recognized as an art form in its own right- hugely popular in England and on the Continent in the eighteenth and nineteenth centuries. This kind of decorative work was sometimes known as “Bavarian Scagliola” in the United States due to its association with immigrant craftsmen from that region. It became widespread in the United States around the turn of the twentieth century when it became a kind of industrial material serving civic, religious, and commercial clients. As the wealth of the nation increased, rich finishes and lavish decoration were in demand in spite of the relative lack of craftsmen with the skills needed to create these dramatic effects. The plaster craft responded by adapting scagliola to serve contemporary construction technology and the quick turn-around required for completion.  

Marezzo

Marezzo seems to have begun in Europe as a way of producing scagliola in reverse, with the finished surface facing downward in the mold and worked from above [Miller 415]. This North American variation of scagliola, used in addition to the traditional kind, was capable of quick assembly and placement on a large scale.  Known to the trade as marezzo or “American Scagliola,” it was used for the finishing of the many courthouses, capitals, hotel, and office buildings built in the classical manner that sprang up in the period after 1900. The scagliola was produced by roving teams of immigrants from Italy and Germany, where the skill was widespread. The accelerating construction demands of American architects and their wealthy patrons, as well as the development of new materials, required innovation from the immigrant craftsmen who were responsible for realizing the great works in plaster, stone, and bronze that appeared on the scene at the turn of the twentieth century.

The development of marezzo was made possible by the development of Keene’s Cement in in England in 1834, a gypsum-based material with a hard finish suitable for polishing, modeling, and sculpture. Marezzo was made of Keene’s Cement, water, fiber, and pigment. It could be produced on site in very large sections of extremely thin, lightweight sections. One piece of marezzo could be wrapped around an entire column. The seam revealing its origin is usually concealed at the back of the column. At classically designed buildings like Richmond’s Jefferson Hotel, the Allen County Courthouse in Fort Wayne Indiana, and countless others:   

The surface of the scagliola on the columns measures from about 1/8 inch to 1/16 inch thick. . . . The scagliola is created on an oilcloth on a flat bench then lifted up on the cloth and “wrapped” around the column” . . . . “During setting, the cloth is peeled off, leaving the scagliola true and evenly curved” [Moretti, 2000].

With marezzo, in which the process of building up the effect of marble was reversed from that of conventional scagliola, the layer of plaster could be sometimes applied to a glass plate, allowing the craftsman to see the finish surface from below during composition.

“Scag,” in America, “was considered to be a trade secret of traveling crews of artisans. The scagliola artists’ work area would be draped and barricaded so they could proceed unobserved” [Staeli 1984]. According to a contemporary writer, “its limited use in recent times is greatly owing to its manufacture being restricted by rules and rigid methods and even prejudices, and being confined to monopolists, who kept the method secret until it was looked upon as a mystery which greatly enhanced its cost” [Hodgson 621].

Restoring Marezzo

Marezzo and scagliola in general are very durable but are subject to discoloration by accumulated grime and by poorly conceived attempts to restore it with transparent coatings that can darken over time. It is essential that architects, property managers, and building owners understand the extraordinary value and history of the material. On occasion, we have been asked if it is possible to lighten the appearance of the finishes to appeal to the tastes of the current generation. Once everyone involved is aware of the value of conserving the decorative finish, we recommend beginning with a small-scale analysis to discern what the finish layers are and to suggest cleaning techniques, then hiring a decorative finishes restoration firm to do the work if the study indicates it. If there is damage to the surface, a plan for repair should be put together in consultation with an artisan skilled in the making and repair of scagliola. The fact that the color and veins run beneath the surface of scagliola means that scratches and chips don’t remove the color so that removal of a small portion of the surface by a careful sanding is possible.  We would not recommend using the same firm for both the analysis and the restoration to ensure that the solution is long-lasting and effective.

The Allen County Courthouse in Fort Wayne, Indiana, stained by many years of heating using coal, was successfully cleaned in 1997 by the scagliola restoration team of Hayles and Howe, of Baltimore, and Montpelier, of Bristol, U.K., in connection with Evergreen Painting Studios. It was determined that the scagliola had been cleaned previously and polished with linseed oil. The smoke was absorbed into the porous plaster, causing discoloration.  The staining was removed with heavy grit wet and dry papers and water stones, and the plaster surface polished. David Hayles and his team also used traditional techniques to repair the extensive marezzo surfaces, some areas of which showed signs of scratching and bleaching from harsh cleaning as well as voids, chipping, and cracking.  “Every time you sand down a surface, you lose more and more of the original layer,” Hayles’ assistant Angela Bakalyar remarks. “For a building like this, you almost need a full-time maintenance crew of skilled people to baby these surfaces. Otherwise, in 100 years, you’ll have another big job” [Moretti 2000]. On the other hand, minor repairs could be done with inpainting rather than attempting to inset new decorative plaster. In some cases, it may be impossible to find a specialist. As was done at the Portland City Hall after damage in 1970, a dedicated local plaster company recreated the techniques of scagliola to repair existing elements and replace missing ones [Staehli 1984].   

Conclusion

The decorative finishes of scagliola are important contributors to the significance of any historic building. Marezzo finishes are representative of the rapid multiplication of elaborately detailed interiors in the period before and after the turn of the twentieth century that was dominated by Beaux-Art classicism. Repair work or cleaning done to significant scagliola and marezzo surfaces should be specified by experienced restoration architects with the direct advice of skilled artisans or plaster specialists experienced in the field of scagliola as consultants.

Sources:

Billings, John Shaw, Records of first director of the New York Public Library, New York Public Library Archives and manuscripts [https://archives.nypl.org/nypla/4937].

Hodgson, Fred T., Mortars, Plasters, Stuccos, Artificial Marbles, Concretes, Portland Cements and Compositions (Chicago: Frederick Drake and Co. 1906). [https://archive.org/details/FredTHodgsonMortarsPlastersStuccosArtificialMarble/page/259/mode/2up]

Millar, William, Plastering Plain and Decorative (London, B. T. Batsford, 1897).

Moretti, Nick, Old World Order, 19 Oct. 2000, Walls and Ceilings [https://www.wconline.com/articles/83816-old-world-order].

Staehli, Alfred M., Scagliola: Restoration of an Antique Plaster Finish in the Portland City Hall, Oregon, Bulletin of the Association for Preservation Technology. Vol. 16, No. 2 (1984), pp. 44-50 [https://www.jstor.org/stable/1494001].

Webb, Patrick, Scagliola, Real Finishes [Blogspot] 22 Nov. 2011 [https://realfinishes.blogspot.com/2011/11/plaster-casting-series-scagliola.html]

Worsham, Gibson, Carrere and Hastings’ Jefferson Hotel, UVA Thesis, 1996 [file://C:\\Users\gworsham\Downloads\Worsham._JohnG_1996_MARH.pdf].