The Many Techniques Of Fused Glass (or some of them)
Heat. It's the magic ingredient in glass fusing and one of the most difficult parts of the process to manage correctly. And when you don't get it right, you'll know it.
Kilns used for fusing glass usually can heat as high as 1800 degrees Fahrenheit. Knowing how heat effects glass helps us control the finished look of your fused glass project. While there are numerous fusing methods, we'll explain the four of the most common here today.
Slumping - Slumping occurs when glass is placed on a mold and heated to between 1200 and 1250 degrees Fahrenheit. The glass becomes soft enough to bend so that it can take on the shape of the mold. Slumping refers to shaping a piece of glass into a mold, while draping glass refers to shaping a piece of glass by allowing it to drape over the mold.
Tack fusing - Tack fusing takes glass to about 1350 to 1375 degrees Fahrenheit. At these temperatures, two or more pieces of glass that are in contact with each other fuse together, but will have seams showing the edges of the two pieces. At e temperatures, the glass will still keep its original shape, size, and thickness.
Contour fusing - As the glass heats past tack fusing temperatures, it starts to become soft enough to melt into a single piece. Contour fusing takes place around 1400 to 1450 degrees Fahrenheit. At these temperatures, the glass begins to flow together into a single-thickness layer of glass, leaving very little of the original shape, size, or thickness of the original pieces. Glass heated to this temperature has a rounded, polished shape but will not be flat and smooth.
Full fusing - When glass reaches between 1450 and 1475 degrees Fahrenheit, multiple pieces fuse together into a single uniform thickness, usually about 6 millimeters thick.
Every piece of glass art or artware is unique and requires unique schedules including how fast the heat is applied and cooled, and the time the kiln is held at specific temperatures along the way. Getting it right takes practice, a knowledge of physics, and a bit of luck.