Penumbra - 2NDS - Trautman
Named for the shadowy edge of a lunar eclipse, Penumbra is a reactive “silvered” cobalt blue, reformulated from one of Paul Trautman's old favorites. Different colors are produced from reduction or oxidation, primarily a wide variety of blues and greens. Reduction can create a luster that you can trap under a clear encasement. However, surface haze doesn’t burn off as easily as amber/purple type glasses.
Second quality glass can have the properties of odd quality glass, but may also have small stones, air bubbles, vary in tone/shade, or the shape can be very out of round. Second quality glass can provide a great value to the right person.