How Iridized Glass Behaves

There are three things you should know about working with iridized glass:

  1. Iridized surfaces do not stick. Just like dichroic glass and micas, the iridized surface on glass never melts and never gets “sticky”. If you try and fuse two pieces of iridized glass together, with the iridized surfaces facing each other, they won’t fuse together. Glass will fuse to iridized glass only when there is “bare” glass in contact with the iridized surface.
  2. The iridized surface doesn’t stretch. Because the iridized surface doesn’t melt, it cannot stretch. If the glass under the irid spreads, the iridized surface crackles like this:
  3. Crackled iridized glass

  4. Iridized glass reflects heat. Projects with large areas of iridized glass are more prone to thermal-shock since the iridized surface reflects more radiant heat than the non-iridized surface. For this reason, you should always decrease heating and cooling rates for schedule segments below 1000° F (538° C).

The first item above, that iridized surfaces won’t stick to each other, is at the heart of the irid-on-irid technique. Let’s get started!