Northstar Turbo Cobalt boro glass is the most intense cobalt blue in the Northstar palette. It is great for stringer application, and stretching out thin. If kept moderately thick, Turbo Cobalt is an excellent faux black. Because of its intensity, NS-033 Turbo Cobalt must be worked in a highly oxidizing flame to prevent graying. If however you are looking for a battleship gray, it can be achieved by working Turbo Cobalt in a heavily reducing flame. For a nice color combination try layering NS-026 Double Amber/Purple over NS-033 Turbo Cobalt.