plateglass

Plateglass refers to large, flat sheets of glass produced by the plate glass process, a historical method for manufacturing window glass that preceded the modern float glass technique. The term is often encountered in architectural and historical contexts to distinguish early flat glass from later industrial methods.

Historically, plate glass was developed in the 19th century as a way to produce clear, uniform sheets suitable for storefronts, skylights, and large windows. The process involved casting molten glass onto a flat surface, followed by grinding and polishing both faces to achieve a smooth, planar finish. Early plate sheets were thick and relatively heavy, with surface distortions and edges that required additional finishing. Production spread to major European and North American glass houses, with sizes gradually increasing as technology advanced.

In terms of properties, plate glass provides good optical clarity and a uniform plane, but sheets could still display waviness, edge flaws, and varying thickness due to limitations of the casting and grinding methods. Because of these imperfections, much of the plate glass used in historic buildings has become a notable feature of older architecture, and such panes are often described as antique plate glass. The weight and brittleness of thick plates also influenced structural and glazing considerations of the era.

The advent of the float glass process in the mid-20th century led to the near-total replacement of plate glass, offering continuous production, tighter tolerances, and lighter, uniformly thin sheets. Today, the term plateglass is largely historical, occasionally used in restoration projects or when referring to antique panes in architectural contexts. See also plate glass, float glass, crown glass.