Smalt at the Warner House in Portsmouth, New Hampshire

Magazine Antiques, Feb, 2005 by Joyce Geary Volk

If the word smalt is unfamiliar to you, you are not alone. Smalt is ground cobalt blue glass, an inexpensive way to obtain a dark blue pigment that goes back at least to ancient Egypt. The expensive way was to grind lapis lazuli imported from Afghanistan, and, indeed, ultramarine, the name for a dark blue color paint today, means "beyond the sea," referring to that source during the Bronze Age lapis trade.

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To make smalt, cobalt ore is smelted, and the resulting cobalt oxide poured into molten glass. Once the glass cools, it can be ground and used in a variety of ways. The Persians were the first to use smalt for blue in ceramic glazes. By the fifteenth century, many Western artists were using it in frescoes or in gesso on wood panel paintings. Michelangelo Buonarroti (1475-1564) used it in his frescoes for the Sistine Chapel ceiling, and when oil painting developed in the High Renaissance, smalt was mixed with that medium for works on canvas. Johannes Vermeer (1632-1675) and Peter Paul Rubens (1577-1640) were among the many painters who worked with smalt before the discovery of Prussian blue in the early eighteenth century. (1)

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Smalt also provided the blue for stained glass and for enamels, but investigation into its use in the decorative arts has been limited. According to Ian C. Bristow, a British historic paint specialist, it was applied in the seventeenth century to the ceiling beams and entablature of the Queen's Cabinet at the Queen's House in Greenwich, England, and to ironwork railings or gates there and at Ham House in Surrey. (2) Patrick Baty, another English historic paint expert, reported finding smalt in the blue color on a plaster frieze in the Queen's Drawing Room at Kew Palace in Surrey and on some ironwork at London's Kensington Palace, (3) minor uses, in other words. Research so far has not uncovered any other evidence of its application in European interiors. It was most surprising, then, to discover that it was used in the parlor bedchamber of the Warner House in Portsmouth, New Hampshire.

The Warner House (Pl. VIII) was built between 1716 and 1718 by Archibald Macpheadris, a wealthy merchant, sea captain, and shipbuilder. Jonathan Warner, another successful trader, married Macpheadris's daughter, Mary Osborne, in 1760, second marriages for both, and they moved into the house, where Warner continued to live until his death in 1814. The couple evidently redecorated when they took up residence, judging by furnishings and wallpaper dating from this period. Subsequent members of the family also made changes to the interior before the house was sold to the Warner House Association in 1932.

As part of an ongoing program to interpret the house to the actual history of its inhabitants from 1718 to 1930, the museum's volunteer staff decided to restore the parlor bedchamber to the occupancy of Jonathan and Mary Warner. An inventory taken after Jonathan's death in 1814 included "10 mahogany Chairs u'r Green damask bottoms" (4) in the room, a clear indication that the Warners used the parlor bedchamber for dining and entertaining, as was common in the eighteenth century. As a first step in the restoration of the room, we had a museum intern take a sampling of the paint layers. The inhabitants had been a frugal bunch, judging by the fact that only six layers were found for the entire period of more than two hundred years. The samples, very small and encased in plastic, were examined under a high-powered microscope, and we were told that the appropriate paint layer for the Warners' redecoration was the third, a dull shade of ocher-beige. However, considering there were only six layers, 1760 seemed a bit early for the third one, so we had another paint analyst and friend of the house take a quick look at the samples. She felt something had been missed but was unable to say exactly what.

As a result, we decided to hire Brian Powell, a conservator and paint analyst at Building Conservation Associates in Dedham, Massachusetts, who is known as one of the best in this field. Powell came in December 2001 and saw what he first thought was evidence of verdigris in the paint. He took a sample about one-half-inch square that went right down to the bare wood for perusal in the laboratory and discovered that what we had was smalt. A subsequent visit confirmed it was not in the ocher-beige layer, but embedded in the underlying coat of pale mauve paint.

We quickly realized that painting the room was going to be a far more complex and costly project than just applying a flat color on the walls, and we applied for and received a grant for the work. Richard M. Candee, former chairman of the Warner House board and a founder of the graduate Preservation Studies Program at Boston University, who had done considerable work on early colonial paint treatments, gave us all the sources he had found on smalt, which saved us considerable time and effort. The references proved fairly easy to locate through the Internet and interlibrary loans. One pertinent example was an advertisement in the New-York Gazette in 1748 for blue smalt, just in from London. (5) Interestingly, the advertisement also mentions "prussian blue," so both were being sold at the same time. We subsequently located other notices offering smalt from Pennsylvania and Boston, so Warner could either have purchased it in the colonies, or, like other wealthy merchants and shipowners in Portsmouth, bought it in England, or had his agent do so for him.