Antique window glass includes all glass and glazing produced using historical manufacturing techniques or materials. Today, antique windows are in high demand in many parts of the world, and some manufacturers create modern reproductions using traditional glass-making techniques. Others salvage antique windows and glass for historic window restoration projects. Antique window glass is known for its very unique and distinct appearance, which differs greatly from modern glass. Most antique glass comes complete with flaws and waves, which add character and help homeowners create a classic, vintage design.
Many of the qualities that make antique window glass unique can be traced to the methods used to manufacture this glass. Prior to the start of the 20th-century, most window glass was hand blown by skilled craftsmen. This hand-blown glass was shaped into a cylinder and flattened as it cooled. The outer edges of each circular portion were cut away to form antique window glass, while the inner circle of glass was melted for reuse. These outer edges featured a wavy, textured surface and were often thicker along the edges than they were in the middle, making them fairly easy to identify today.
In some cases, the thick inner circle of hand-blown glass was not remelted, and was instead used in round windows of the period. This thick, round section of glass is known as crown glass. Crown glass has a very thick, wavy texture that makes it difficult to see through. It is characterized by swirls and ripples along the surface, making it an excellent option for bringing light into a home without compromising privacy. Today, crown glass is highly coveted for historic renovations, as very little still exists compared to other types of antique window glass.
From the start of the 20th-century to the 1950s, window makers switched to a machine-blown technique rather than traditional hand blowing. This resulted in glass that was much more even and smooth compared to earlier glass designs. Machine-blown glass still features a slight wave in the surface that makes it easy to distinguish from modern glass.
After the 1950s, the majority of glass was produced using a float technique. Float glass manufacturing results in a near perfect surface, with each pane smooth and even. Float glass typically features a consistent finish, with none of the wavy lines of earlier glazing.
In addition to the clear glass produced using these methods, antique window glass also includes colored or stained glass. Salvaged stained glass panels often demand high prices, and are invaluable for those pursuing a historic restoration project. These windows often feature religious or floral patterns, with leaded panes connecting pieces of glass together in a single unit.