Iridescent fusing glass is a specially coated glass that can be fused in a glass fusing kiln.
A metal oxide coating is sprayed on hot glass during the manufacturing process, this coating leaves a shimmering metallic rainbow effect on the glass. The coating is applied to one side only.
Stained glass is also treated in this way, the shimmer will disappear when the glass is back lit allowing the normal glass color to shine through. The same applies to fused iridescent glass.
Iridescent fusing glass can be purchased in a number of COE's suitable for glass fusing projects. Bullseye Glass, Uroboros Glass and Spectrum Glass make their own colored shimmering iridescent sheets.
Plain and textured sheets are available for purchase.
Iridescent glass can be used for normal fusing glass projects or fused glass art jewelry items.
Variations in appearance of iridescent coatings can occur across a sheet of glass from edge to edge or between glass sheets of the same color. A gold colored coating may change to a silver or magenta color across one third of the sheet.
Some coatings may burn off at about 1300F (704C), it is advisable to always purchase glass that has been made to cope with higher glass fusing kiln temperature.
It is a good idea to fuse iridescent glass face down to lessen the chance of the coating burning away, minimize the time spent above 1300F (704C) in the glass kiln even when fusing glass that has a higher burn off temperature.
When fusing a number of pieces of iridized glass they must be fused coated side to uncoated side, otherwise the metallic coatings will not fuse together.
Iridescent glass is easily fused with other art glass colors to produce lovely shimmering designs.
Iridescent glass is ideally suited for use in textured glass slumping molds, the shimmering effect can be magnified by using this type of mold.
FINDING THE COATED SIDE
It is sometimes difficult to determine the coated side on some iridescent glass pieces, the same technique as used with dichroic glass can be employed to find the coated side.
Hold a sharp pencil or other pointed object at an angle against the glass, look at the reflection, on the coated side there will be no gap between the point and the glass.
If there is a gap then that is the uncoated side. This technique may not work properly on black or dark glass as it may be difficult to see.
If a small piece is nibbled away with grozing pliers it is possible to see damage to the coated side with no apparent damage to the uncoated side.
Remember to mark the coated side as well as any cut pieces to avoid having to test the glass again.