Kugler Gold Iris Reduction Stringer. Stringers are approximately 13 inches long and 2-4mm in diameter. Reduction glass forms a metallic luster similar to a raku-like effect. To use, heat bead enough to stick the stringer to it and melt it fully into the bead if desired, melt the stringer very thinly to the surface for best compatibility. Keep the glass molten and adjust the torch to a strong reduction flame. When you reheat the bead, the reduction flame causes the metalic oxides to come to the surface.