Easily Add Intricate Designs to Glass Glassline pens are a lining and shading material for glass. They are easy to use and can be applied between multiple layers of glass or on the top surface for a complex dimensional look. Glassline pens can also be sprayed on to achieve subtle shading variations. Glassline is compatible with both 90 COE and System 96 glass. Glassline pens are lead free and food safe. Kit contains 14 colors, each 2 oz., plus a tip set (3 tip sizes: bold, medium & fine). Glassline Tip: For best results "tack fuse" individual sheets of glass before stacking your full fuse. Best fired to 1500 F., but may be fired lower or higher depending upon your desired results. For more tips and instructions, click "View User Manual". Glassline Pens should be stored with the caps firmly in place, and are best stored at room temperature. Pens that have been frozen or have been exposed to high temperatures may require extra mixing to ensure proper consistency. Delphi Tip: For thinner lines pour a few drops in a bottle with a smaller tip. Butterfly project below created with Glassline Pens, using multiple layers of glass. Artist: Jaime Dobson. Vase project created by Kim Lyle. Glassline chalks and pens on fusible paper, fused in glass.