Penumbra Frit #25 - Coarse - 4 oz. - Trautman
The course frit grade resembles a pretzel salt size. Paul Trautman reformulated one of his old favorites and dubbed it "Penumbra", from the astronomy term for a partial eclipse shadow. Penumbra is a reactive, striking "silvered" cobalt blue, which reduces and oxidizes for a range of colors and effects.