NS-001 Of the four shades of cobalt blue Northstar produces, this ranks as the second lightest. NS-001 is well suited for small blown work, as well as sculpture when a medium transparent blue is desired. NS-001 Cobalt Blue can take a lot of heat and can be worked in a wide range of flame settings. Though the color is extremely intense, be sure to stay out of reducing flames to prevent any dulling or graying. Priced Per Pound.