Ever wonder how glass gets that interesting spiderweb-like effect? By dunking an extremely hot piece of glass into a container of water, crackles form on the surface and create what is known as crackle glass. Offhand glassblowers and lampworkers often use this surface treatment to add interest and depth to their pieces. Create your own crackle technique with a piece of solid glass and a torch. Use a small piece of glass to get a feel for the process and see how the crackles enhance your glass designs.
Place a clear container of water within reach, but not so close that the steam from the glass hits you in the face.
Remove any impurities from the tip of the glass. Heat the rod and pick off the end with your tweezers. Impurities will affect the overall look of the crackle glass if you do not remove them.
Rotate and heat the rod in the flame of your torch to form a small gather of glass.
When the glass is white hot, remove it from the flame. Wait 15 to 20 seconds, or until the glass loses its red glow, and plunge it into the water. Pull the glass out immediately. This process is determinant on the size of glass and the time in the water. Practice this procedure to figure out what yields the crackle results that you desire.
Heat the top of the glass on the edge of the flame for just a few seconds. Quickly move all of the crackled glass in and out the back of the flame to flash heat it. If you lose too many crackles during this process, repeat the heat and plunge process.
Place your glass in a kiln to anneal it.
Never begin lampworking until you understand the health and safety considerations and have set up a proper ventilation system.