What Is Glass Slab Art? The Ancient Thick Glass Technique That Nearly Disappeared
Walk into a cathedral in France or a civic building built in the 1950s. If the light comes through the windows in heavy, jewel-like chunks — deep reds, electric blues, thick amber — you may be looking at glass slab art. Most people have walked past it without knowing it has a name. Fewer still know how close this technique came to vanishing entirely.
What Is Glass Slab Art?
Glass slab art — known in French architectural circles as 'dalle de verre' — uses chunks of thick, colored glass typically two to four centimeters deep, set into a matrix of concrete, epoxy resin, or cement. The result is architectural glass art with a weight and luminosity that no other glass technique produces.
Unlike traditional stained glass, which uses thin sheets held together by lead strips (called cames), glass slab art is structural. The glass chunks are chipped and faceted with a hammer and chisel before setting. This faceting creates irregular surfaces that refract light at unpredictable angles — the light a glass slab panel casts changes dramatically between morning and afternoon, and between summer and winter.
The Origins of Glass Slab Art
The technique was developed in France in the early 1930s, primarily by artist and glassmaker Jean Gaudin. Gaudin was experimenting with ways to create bolder, more luminous architectural glass — the thin stained glass of medieval cathedrals was beautiful but lacked the visual weight he was looking for in modern buildings.
By embedding thick glass slabs into concrete rather than joining thin panes with lead, Gaudin achieved something entirely new: glass that functioned as a structural material while also being a medium for color and light. The concrete matrix could be formed into any shape. The glass could be any color. The scale was limited only by engineering.
The technique spread through Europe during the 1940s and 1950s as architects embraced modernism and sought materials that felt both ancient and contemporary. Churches, museums, airports, and universities commissioned glass slab art installations across France, Germany, the United States, and beyond.
The Mid-Century Peak — and the Decline
Glass slab art reached its peak in the 1950s and 1960s. The technique suited the architectural ambitions of the era perfectly: bold, colorful, structural, and capable of covering large surfaces. Major artists including Gabriel Loire and Fernand Léger produced glass slab works for significant public buildings.
The decline came gradually. As architectural fashions shifted in the 1970s and 1980s, the demand for large-scale decorative glass art fell. Glass slab art requires specialist knowledge, significant material investment, and skilled labor that cannot be easily mechanized or accelerated. As the artists who had developed the technique aged, fewer apprentices trained to replace them.
By the late 20th century, glass slab art had largely disappeared from architectural practice. The buildings containing the great mid-century installations remained, but the studios capable of producing new work had dwindled to a handful worldwide.
How Glass Slab Art Is Made: The Process
Step 1 — Creating the Glass Slabs
The process begins with casting thick slabs of colored glass. The color is achieved by adding metallic oxides during the glass-making process — cobalt for blue, iron for green and amber, gold or selenium for red. The slabs are typically cast in standard tile sizes, then cut down as needed.
Step 2 — Faceting with a Hammer and Chisel
This is the step that makes glass slab art unique. The glass artist uses a hammer and a tungsten carbide chisel to chip the edges and surfaces of each slab. The chips create facets — small, angled surfaces that catch and scatter light. A skilled practitioner can control the faceting to direct light in specific ways, creating compositions that are designed as much with light as with color.
Step 3 — Setting the Design
The faceted glass pieces are arranged according to the artist's design on a flat work surface. The design is typically drawn at full scale beforehand, so the artist can place each piece precisely. The gaps between pieces are where the concrete or epoxy will flow.
Step 4 — Pouring the Matrix
Concrete or epoxy resin is poured over and around the glass pieces. This matrix binds everything together, creates the structural support for the panel, and forms the 'negative space' of the design — the dark lines between the colored glass. The color and texture of the matrix affects the final appearance as much as the glass itself.
Step 5 — Curing and Finishing
The panel cures for a minimum of several days. Once set, the surface is cleaned and sometimes sealed. The finished panel is extraordinarily durable — far more resistant to impact and weathering than traditional stained glass.
Glass Slab Art vs. Traditional Stained Glass: Key Differences
• Thickness: Glass slab art uses glass 2–4cm thick. Traditional stained glass is typically 3–6mm.
• Structure: Glass slab art is set in concrete or epoxy. Stained glass is held with lead came.
• Light quality: Glass slab art produces heavy, jewel-like color. Stained glass produces translucent, delicate color.
• Durability: Glass slab panels can survive decades of outdoor exposure. Stained glass requires more maintenance.
• Scale: Glass slab art is better suited to large architectural applications. Stained glass is more adaptable to detail work.
• Technique for cutting: Glass slab art uses hammer and chisel. Stained glass uses a glass cutter and breaking pliers.
Where Glass Slab Art Is Used Today
The few studios worldwide that still practice glass slab art work primarily on architectural commissions — churches, hotels, private residences, and public buildings seeking feature walls, windows, floors, and panels. The technique has also found application in furniture making, where thick glass slabs embedded in a concrete and steel matrix create surfaces of unusual durability and beauty.
The combination of recycled glass with the glass slab art technique has opened new possibilities for studios working with sustainable materials — the thick slabs can be cast from recovered glass, giving material that would otherwise be waste a permanent, structural second life.
Kitengela Glass, founded in Kenya over 35 years ago, is one of a small number of studios worldwide still actively producing glass slab art — using recycled Kenyan glass in both architectural commissions and furniture pieces.