General Glass fusing is a term used to describe glass that has melted (heat-processed) in a kiln at a range of high temperatures from 593 ° C to 816 ° C There are 3 main distinctions for temperature application and the resulting impact the glass. The heating in the lower ranges of these temperatures 593-677 ° C is called Slumping. The heating in the middle ranges of these temperatures 677-732 ° C is called "tack fusing". The heating of glass at the higher range of this series of 732-816 ° C is called a "full fuse". All these techniques can be applied to a task to separate heating glass to add depth, texture and form. History While the precise origins of glass fusing techniques are not known with certainty, there is archaeological evidence that Egyptians were familiar with the basic techniques about 2000 BC, although this date is generally accepted by all researchers, some historians argue that the most early melting techniques originally developed by the Romans, who were more productive craftsmen in melting and was the original method of making small glass objects for approximately 2,000 years until the development of blown glass. The blown glass replaced largely due to the melting of greater efficiency and usefulness. While the art of glass generally went through a revival during the Renaissance, the fusing was ignored largely during this period as well. The fusing began to regain popularity in the first part of the 20th century, especially in the U.S. during the 60s. The modern glass fusing is a widespread hobby but the technique is not widely used for large scale glass production. Techniques Most modern methods of melting include stacking, or layering of thin sheets of glass, often using different colors to create drawings or other images. The pile is then placed in the kiln (which is almost always electric, but can be heated by gas) and then melt through a series of ramps (rapid heating cycles) and "soak" (keeping the temperature at a certain point) to begin to link together the separate pieces. The longer the kiln is held at maximum temperature, the more detailed will melt, eventually softening and rounding the edges of the original form. Once the desired effect on the maximum temperature, the furnace temperature will be thrown quickly through the temperature range 815 ° C to 573 ° C to avoid devetrification. Then cooled slowly over a specified time and temperature specified range that are essential to the orderly process of cooling.  This prevents the abnormal cooling and breakage and produces a strong finished product. This cooling takes place normally for a period of 10-12 hours in 3 stages.                                                                                                                                                                                                 Source:  Stefanidis Chris - Stefanidou Zoe  G.P.