A glass knife
is a knife
with a blade composed of glass
. The cutting edge of a glass knife is formed from a fracture line, and is extremely sharp.
Glass knives were used in antiquity due to their natural sharpness and the ease with which they could be manufactured. In modern electron microscopy
, glass knives are used to make the ultrathin sections needed for imaging. Diamond knives
are also extremely sharp, and the edge lasts much better than glass, but they are extremely expensive.
Beginning in the Stone Age
, glass knives (and other tools, such as arrowheads) were produced through a process known as knapping
or lithic reduction
. Although such bladed tools were often made of stone, naturally occurring glasses such as obsidian
, natural volcanic glass, were also commonly used.
From the 1920s through the 1940s, Dur-X glass fruit and cake knives were sold for use in kitchens under a 1938 US Patent. Before the wide availability of inexpensive stainless steel
cutlery they were used for cutting citrus fruit, tomatoes, and other acidic foods, the flavor of which would be tainted by steel knives and which would stain ordinary steel knives. They were molded in tempered glass with ground edges.
Modern glass knives were once the blade of choice for the ultrathin sectioning required in transmission electron microscopy
because they can be manufactured by hand and are sharper than softer metal blades; the crystalline... Read More