Cylinder glass
Cylinder glass, also called muff glass, is made by blowing a long cylinder of glass, cutting off the ends and slitting it lengthways. The cylinder is then reheated and flattened into a sheet. Larger sheets could be made this way than with crown glass, which made it the main method for window glass in the nineteenth century.
Hand-blown cylinder glass is the type usually sold as antique glass today and it is the usual choice for restoration work. Cylinder glass shows fine lines and a slightly uneven surface, which gives it more life than machine-made glass.
In the twentieth century, machine-drawn sheet and later float glass took over the market for ordinary windows.