Warm Glass Supplies Challenges and Fun!
The term "warm glass" refers to slumping, fusing, and other processes for molding glass which occur between temperatures of 1100F and 1700F.
This may not sound warm, but it is compared to the temperatures used to blow glass, which may exceed 2000F.
Another term for this process is kiln-forming.
Glass fusing is a process for using a kiln to join pieces of glass together.
If heat is applied to glass taken from a ware cart, it softens and becomes fluid and flows together.
Pieces of glass will stick or fuse to each other and when cooled the piece will be solid and unbroken.
Slumping involves bending and shaping glass using the kiln's heat to make already-fused glass take on the shape of a bowl, plate, or other object.
Some other warm glass techniques are "combing", which means using tools to distort the shape of glass while it is still hot and "fire polishing" which involves heating glass in a kiln just enough to make it smooth and shiny.
"Kiln casting" involves melting glass in a mold inside of a kiln, "pate de verre" means forming shapes by heating a paste of glass inside a kiln and "glass casting" means pouring molten glass into a mold.
The basic requirement is having a kiln.
Ceramic kilns can be used for warm glass, but if possible it is better to use one that has been specifically engineered for firing warm glass.
It is necessary to monitor the temperature within the kiln, which is usually accomplished with a pyrometer.
For slumping techniques, molds are necessary also.
Any kind of glass can be used for slumping and fusing, but some glasses work better than others.
Since it is likely that different pieces of glass will be used in the same project, it is necessary to make sure that the glasses are compatible - that is, that they expand and contract at similar temperatures.
This prevents cracking or shattering when the pieces cool.
When starting out it is best to use glass which has been "Tested Compatible" by the company from which you purchase warm glass supplies.
Glass for slumping and fusing can be purchased in 3/8" thick sheets as frits which are small pieces ranging in size from powder to 1/2" in width, as stringers which are long thin glass threads, as rods which are thicker cylinders, as shards and confetti which are glass slices a bit thicker than paper and as cullets, billets, patties, or dale which are different sizes and shapes of chunks of glass used in casting.
The basic slumping and fusing process consists of five main parts: the heating phase, in which the temperature in the kiln is raised from room temperature to the point where fusing takes place; soaking phase, in which the temperature is held at a given point for a certain period of time; cooling phase, in which the temperature is brought down from its high point to just above the annealing temperature; annealing phase, a most critical step which relieves stress in the glass; and cooling to room temperature phase, in which the glass becomes cool enough to touch.
Warm glass is a very rewarding and enjoyable technique; for more information, see your art glass supplier.
This may not sound warm, but it is compared to the temperatures used to blow glass, which may exceed 2000F.
Another term for this process is kiln-forming.
Glass fusing is a process for using a kiln to join pieces of glass together.
If heat is applied to glass taken from a ware cart, it softens and becomes fluid and flows together.
Pieces of glass will stick or fuse to each other and when cooled the piece will be solid and unbroken.
Slumping involves bending and shaping glass using the kiln's heat to make already-fused glass take on the shape of a bowl, plate, or other object.
Some other warm glass techniques are "combing", which means using tools to distort the shape of glass while it is still hot and "fire polishing" which involves heating glass in a kiln just enough to make it smooth and shiny.
"Kiln casting" involves melting glass in a mold inside of a kiln, "pate de verre" means forming shapes by heating a paste of glass inside a kiln and "glass casting" means pouring molten glass into a mold.
The basic requirement is having a kiln.
Ceramic kilns can be used for warm glass, but if possible it is better to use one that has been specifically engineered for firing warm glass.
It is necessary to monitor the temperature within the kiln, which is usually accomplished with a pyrometer.
For slumping techniques, molds are necessary also.
Any kind of glass can be used for slumping and fusing, but some glasses work better than others.
Since it is likely that different pieces of glass will be used in the same project, it is necessary to make sure that the glasses are compatible - that is, that they expand and contract at similar temperatures.
This prevents cracking or shattering when the pieces cool.
When starting out it is best to use glass which has been "Tested Compatible" by the company from which you purchase warm glass supplies.
Glass for slumping and fusing can be purchased in 3/8" thick sheets as frits which are small pieces ranging in size from powder to 1/2" in width, as stringers which are long thin glass threads, as rods which are thicker cylinders, as shards and confetti which are glass slices a bit thicker than paper and as cullets, billets, patties, or dale which are different sizes and shapes of chunks of glass used in casting.
The basic slumping and fusing process consists of five main parts: the heating phase, in which the temperature in the kiln is raised from room temperature to the point where fusing takes place; soaking phase, in which the temperature is held at a given point for a certain period of time; cooling phase, in which the temperature is brought down from its high point to just above the annealing temperature; annealing phase, a most critical step which relieves stress in the glass; and cooling to room temperature phase, in which the glass becomes cool enough to touch.
Warm glass is a very rewarding and enjoyable technique; for more information, see your art glass supplier.