600-640 – One-Stroke (concentrated underglazes) – Are intended as the name implies, to give opaque coverage with one brush stroke. They are ideal for painting on designs and can be used in the same manner as underglazes. They are very similar in use to the underglazes described above. However, they have approximately twice the concentration of color as the underglazes and are generally of a thicker consistency. All our one-stroke colors are lead-free, A/P non-toxic and dinnerware safe when covered with a dinnerware safe clear glaze.