The Heart Paperweight - Fusible Glass Slumping Mold Outside dimensions: 4" x 4" x 1" H. Finished Heart dimensions: 3" x 3" x 1/2" H. To use, simply pretreat the mold with kiln wash or nitride spray, and slump your prefused or sheet glass (cut to size) using a slumping kiln schedule. For best results, always elevate this mold off the kiln shelf by at least 1" before firing. Comes with a complete New Hampshire Craftworks slumping and care schedule included! The heart sample was created using our Be My Valentine Designer Coarse Frit Mix. Remember to always elevate this mold at least 1" off the kiln shelf for best results.