What is annealing?
Why Is It Important? And How To Do It. The following is an excerpt from our annealer manuals. Annealing is the process of making the entire glass item uniformly hot and holding that temperature steady long enough to remove all stress caused from the manufacturing process. The annealing cycle also includes cooling down slow enough so as to not allow too much stress to build back up. When glass is held at a steady temperature over a length of time, it is called soaking. Soaking the glass at a higher temperature has the advantage requiring a shorter soaking time for the stress to dissipate, but also runs the danger of being so hot that it may distort under its own weight or of sticking to something. The glass will also need to cool down a through a longer temperature range, and this will take longer than if it were annealed at a lower temperature.
What does annealing mean? What is annealing? is a question that Ive been asked many times. Annealing is the process that takes place within a kiln, during a soak cycle. During this process, the temperature is slowly reduced so that the stress on the molecular level is removed the beads. Since I normally use either 104 COE or 96 COE glass, my kiln is pre-heated to 960 degrees during the time Im working at the torch. The beads are then directly placed into the kiln and held there until the last bead is made. After the last bead is made, I program the kiln to stay at 960 degrees for one hour. Unless I have made huge beads, then I will add time to that section of the cycle. The kiln has been pre-programmed to slowly ramp down in temperate. When the temperate reaches 850 degrees, the kiln will hold that temperate so that the beads can stabilize again. At this phase of the process, the extra little gases that can be trapped in the glass are stabilized.
Annealing is the process by which both metal and glass are treated with heat in order to change their properties. If the process is applied to glass it is held at a high temperature to rid the item of any stresses that it underwent in the manufacturing process. Once the glass has been subjected to a consistently high temperature for the required length of time, it is then slowly cooled, which acts to seal in the piece’s strength and durability. As with the glass annealing process, when metal is annealed it is first introduced to a very high temperature before being cooled to seal in the metal’s ductility and strength. The process of subjecting glass to a steady temperature is termed “soaking.” The higher the temperature the glass is soaked at, the shorter the period the glass needs to be exposed to such a temperature. Of course, glass exposed to very high temperatures requires longer to cool down.
To anneal the steel means to make it soft. To anneal a piece of steel, you heat it up past its critical temperature and then let it cool as slowly as possible. Many people put the steel in vermiculite because of its insulating properties and let it cool overnight. The steel is soft for drilling, filing or grinding.
Annealing is the process used to relive stress in glass during cooling. This is accomplished by maintaining a consistent temperature through the entire body of glass. The glass is held at a temperature just below the temperature at which that specific glass will start to move due to heat. Heat is transmitted very slowly through glass, so the glass has to be held at the annealing temperature anywhere from an hour to days or weeks. The annealing process is dependant upon the thickness of the glass. The glass is then brought down in temperature while maintaining a consistent temperature throughout the body of glass. The cooling time also depends on the thickness of the glass; the thicker the glass the slower it will loose heat from its center. When the kiln cools down faster than that which is required by the thickness of the glass, heat is applied to the top or bottom of the glass to maintain a consistent cooling gradient throughout the body of glass. Stresses caused by incompatibility o
