A fusing glass mandrel is used to create a hole or channel in a piece of glass during the glass fusing process.
These openings are used to attach the piece to another object or as channel for pendant chains or cords.
Mandrels are quite often used in the making of fused glass beads or other jewelry items.
The mandrel can be made from a material that burns away during fusing such as a wooden tooth pick, or a stainless steel rod that will withstand high glass kiln temperatures.
Stainless steel welding rods are frequently used as they are readily available, particularly from stores that supply tools and supplies for hand made flame worked glass bead artists.
The most popular stainless steel sizes are 1/16", 3/32" and 1/8" rods. Another alternative is piano wire rods that are usually available in model aeroplane hobby stores.
Piano wire comes in large range of sizes.
For larger size holes stainless steel tubing of various diameters will produce excellent results.
To prevent glass from sticking to a mandrel, the mandrel must be coated with bead release or separator which is a mixture of high fire clay and alumina.
Release is available in different strengths, some of which have a stronger holding power than others.
Usually for fused glass work strong release is not required, unlike bead making the glass is not twisted and formed on the rod.
Bead release is applied along the mandrel past the glass edges so that the glass does not contact the mandrel.
Bead release is used on all mandrels whether they be steel or wooden.
Dipping the mandrel into bead release works better than trying to paint release onto the rod, 1/32" thickness should be enough.
Wet coated rods should be stored upright, a piece of styrene foam is an easy way to do this.
The release should be dry before being used with the art glass item.
Once the art glass is set up with the fusing glass mandrel the item can be placed in the glass fusing kiln.
After fusing excess bead release may need to be removed from inside the glass with a bead reamer or a diamond tip power tool.
Strips of fiber paper can also be use to make holes in fused glass pieces.