Specifying Mosaics

			Whether specifying a stock mosaic border around a swimming pool or a custom-designed pictorial on a dining-room wall, mosaics are a personal and enduring design element inside and out. Here, a mosaicist imparts technical information and the particulars of mosaic specification. by George Fishman, Fishman Mosaics, Miami Shores, Fla.
History Types & Materials Stock vs. Custom For Architects & Designers Hints & Tips Buying Guide to Suppliers

In this article I hope to provide guidelines and encouragement for design professionals who wish to incorporate mosaics in a remodeling or new-construction project. If I succeed, the specification process will show how attention to detail will produce a beautiful and enduring reward. Recent design trends have increasingly featured mosaic treatments of walls and floors. Large manufacturers and small studios present a proliferation of beautiful borders and medallions in various materials. Classical motifs are enduringly popular, but custom work can be created to enhance any decor.

History
More than 2,000 years ago resourceful home builders, tired of the problems inherent in "traditional" dirt floors, developed mortars that were spread out over gravel beds, into which they pressed stone chips. The embedded stones formed terrazzo-like pavements and primitive tiling patterns. Over time, artisans developed sophisticated layout schemes that were disseminated throughout the Mediterranean basin and beyond. This work came to be called Mosaics.

The conquests and settlements of the Greeks and Romans took artists and artisans further afield. Elegant mosaic pavements and wall decorations enhanced baths, villas, temples, and eventually Christian churches from Palestine to Britain to Spain and North Africa. The styles and methods of mosaics evolved over later centuries with occasional declines and revivals. The mosaics that most of us in the Americas are familiar with exist in Western Europe where they decorate the fountains, pavements, and grottos of Pompeii, the facades of palazzi on the Grand Canal, humble 5th-century village churches, and the grand cathedrals of capital cities. Art Deco, Art Nouveau, and the various Classical Revival styles all have adopted mosaics in both public architecture and private homes. Types Mosaic design generally falls into two camps: the pictorial and the geometric. However, many popular motifs -- vines, waves, chains, compass roses -- are stylized forms of natural subjects. Greco-Roman mosaics often combined a realistic pictorial subject -- a landscape, a mythical creature, a still life -- placed within a solid-color field and surrounded by a geometric border. This design approach still works today. Rather than borrowing the classical subjects, however, residential clients might opt to work with a mosaic artist to invent a highly personal subject for the picture. Showroom catalogs and reference books will show scores of field patterns, borders, and medallions. If desired, a design professional can then generate variations, keying in to a preferred color scheme and to the home's particular layout.

A mix of vitreous glass and unglazed porcelains were used to fabricated "Deco Rugs," based on 1930s French rugs designs. They are inserted "casually" in a field of honed limestone. Critical surface leveling was achieved across various thicknesses of materials. (Master Installer, Gerard Scobie; Interior Designer, Barbara Hulanicki; Photographer, Lanny Provo.)

Materials
The range of mosaic materials is first daunting, but ultimately, inspiring. Although some are more workable than others, most stone varieties that are sold as nominal 10-mm-thick (3/8 in.) stone tiles can be cut into small pieces (tesserae or chips) to create custom mosaics for walls or floors. Polished, honed, or split surfaces each have a unique appeal. Semi-precious stones such as onyx, agate, and lapis make luscious accents and boost the palette into the brighter colors. Smooth pebbles create a striking textured effect -- even for pictorial subjects -- though usually in informal settings, such as patios and gardens.

Glass for mosaics is manufactured in two principal forms: First is the so-called vitreous or Venetian, a thin, uniform glass tile with a flat, slick surface. At least a half dozen major manufacturers sell it in North America; each produces a palette of up to about 75 colors, including gold. The most common tesserae size is 20x20 mm, although 10 and 25 mm also are available. Vitreous glass is usually sold in cartons of 30-x-30-cm sheets. The tiles -- in a solid or mixed-color field -- are glued face down on paper at the factory. This premounting allows them to be installed expeditiously: after the tiles are held in place with thinset, the paper is moistened and then peeled off.

Vitreous is the least-expensive mosaic glass and is suitable for interior and exterior walls and ceilings. However, it is rather delicate and slippery; use caution before specifying it for flooring. When used for pictorial work or hand-cut borders, the glass first is soaked off the sheets, then cut and assembled into the layout. Glued paper or clear adhesive film is then applied to the completed design 's face for transport and installation.

"Passion Vine Medallion" is an original design fabricated of unglazed porcelains with vitreous-glass accents, was installed in a simple tile field. The pictorial element is surrounded by concentric border motifs, which could be repeated at the floor perimeter.

Glass smalti is the traditional material for mosaic murals. The tesserae are thicker and more irregular than vitreous glass. They are hand-cut from slabs, and their fractured faces ultimately constitute the finished surface. Because smalti is made for subtle portraits and religious scenes, thousands of colors are manufactured, although not all are readily available. Smalti is sold loose rather than sheet-mounted, and is most suited for custom work. As with vitreous glass, the mosaicist face-mounts her layouts on interlocking sheets of paper or cloth prior to thinset mounting. The rich palette and rippled, lustrous surface of smalti are unique. At least one manufacturer also makes a glass specifically for floors. These tesserae measure 12 x 12 mm and 8 mm thick, and are spaced wider on the sheets than vitreous glass.

Ceramic tile varies beyond the scope of full discussion here. Generally speaking, unglazed porcelains can be used for either walls or floors. Modules of 25 x 25 mm are available in about 40 colors for nipping into patterns or pictures. Glazed tiles are less commonly used for stock borders than are unglazed ceramics, stone, and glass. (Commercial glazed "faux mosaics" with embossed grout lines are an exception.) Glazed tiles are generally produced in larger modules that need to be cut or shattered into appropriate sizes for making custom mosaics. Glazed wall tiles should not be used for floors; they are slippery and scratch easily.

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