Fusing glass in a kiln


First the glass is cut unto pieces, and then assembled..

A base layer is cut. If this is for jewellery, then this layer made from coloured glass.

If a hole is required for hanging, then a piece of kiln blanket cut in a strip is glued to the base layer, and a small strip of plain clear glass is stuck either side of it to ensure a properly sealed channel is formed after fusing.

Decorative pieces are then stuck in overlapping layers. If dichoric glass is used these layers will be transparent to give depth to the finished piece. Finally, a clear layer is placed on top to give the piece brilliance.

If the piece is complex, then it may be assembled in stages allowing the glue to harden between each stage, so that the layers don't slip off.

To produce irregular shapes, the layers are cut into odd shapes and assembled in a random manner, and the final top layer is omitted. If the piece is dichroic glass, then some layers will leave the coated side of the glass uppermost producing differing surface textures to the final piece.


assembling glass




The assembled and dried pieces are then fired in a kiln to about 800 degrees C.

Picture on right shows a recently fired kiln of mixed dichroic pendants, earrings, cufflinks, and earrings.

Note the channel in the pendants.


full kiln


  The temperature and type of glass determine whether the final piece will be a smooth rounded shape, or whether the layers will stand proud in a 3d manner as shown on the right.   3 d pendant

In order to shape a piece into say a bowl, the glass is first fused as described above, then further fired at a lower temperature using a mold. depending on the way the mold expands on heating, the glass is either placed over the convex side of the mold, and allowed to slump over it, (for example stainless steel) or onto to concave side, and allowed to slump into it.

Large pieces of glass, especially those fired twice run the risk of becoming devitrified, ie, the surface develops an opaque bloom and a rough texture. To prevent this, a solution containing borax is panted over the upper surface

Finally, the pieces are washed, the kiln blanket strip for the channel is removed, and any sharp spurs sanded off.


photo taken of a kiln of red hot glass during a flash vent showing a piece being slumped into a star shaped bowl.

kiln showing slumping