Glassline Bubble Pens are a lining and shading material for glass. They are simple in design, easy to use, and are water based. Glassline Bubble Pens are formulated to be used between layers of glass. When sandwiched between glass, the lines will develop a colored line made up of many micro bubbles. A metal tip set is highly recommended to achieve these fine lines. Glassline is compatible with most types of glass from Float to COE 90 and 96. While best fired from 1450-1500 degrees, it may be fired lower or higher, depending upon your desired results. Glassline Bubble Pens are lead-free and food safe. Sold in a 2 oz bottle. Pack of 1.