There have been several methods used over the centuries to cut glass. When stained glass was first made it was shaped using a ‘grozing iron’ which was a rod of iron with bent hook at one end or both ends. The hook overlapped the edge of the glass and a small piece was levered off, repeating this motion created the shape required with a nibbled edge all the way around.
The lead calme (came) hid the edge of the glass replacing the roughness with the straight lines of the lead. However, this cutting method was time consuming so to save some time to get the general shape in the first instance a hot tipped iron from a coal furnace was used to draw a heated line on the surface of the glass, the heat made the glass expand in a very localised way and crack was induced by ‘thermal shock’. It was then nibbled (grozed) to size. Later diamond tip cutters were used to get the general shape which were good for straight lines but not so good at going around corners, a solution to this was later found in the wheeled glass cutter we know today.
These two types of cutter (diamond-left, wheel-right), can still be bought today and have notches which can be used for nibbling (grozing).
Today most glass cutters have tungsten carbide wheels which last a long time and come in a variety of shapes and sizes. Here are some examples we use in our classes which aim to make glass cutting easy to use and a comfortable experience, hence the various shapes to fit different sized hands with different pressure points.
After scoring the glass with the glass cutter and breaking it, the new edges sometimes need to be lightly grossed to get rid of sharp edges using growing pliers. This is the standard style of grozing pliers available today which are relatively cheap to buy.
In the second part of this topic I’ll go through the best methods of cutting glass including straight edges, curved edges, circles and holes.
cutting glass, stained glass, how to cut stained glass, stained glass technique, glass cutters, glass tools