The Science and Art of Glass Blowing at Mini Maker Faire
Most art glass begins its studio life as a molten, honey-like glob, wound out of a high temperature crucible onto a long steel straw. Your face probably remembers the last time you took a pizza out of the oven – imagine temperatures five times hotter and that’s what it feels like to gather glass out of a furnace. Soda-lime glass, essentially sand, soda, and lime (SiO2, Na2CO3, and CaO, respectively), is the type of glass most commonly used in art and manufacturing. The process of making glass can also happen in nature the instant lightning strikes sand and forms hollow tree-like structures called “fulgurites.”
Some glass artists work with sodium borosilicate glass (e.g., Pyrex®), a glass with a greater tolerance for temperature extremes due to its lower coefficient of thermal expansion. Long Pyrex® rods and tubes can be held by unprotected hands over a propane burner and melted and manipulated to form artistic shapes and vessels. However, soda-lime glass takes less energy per pound of glass to melt, and thus lends itself to larger works of art such as those featured at the Franklin Park Conservatory by American glass artist Dale Chihuly.
Working with soda-lime glass gives artists a rich and vibrant color palette, achieved by adding various metal salts to the glass, e.g., two cobalt salts, CoO and CoAl2O4, both give rise to the popular “cobalt blue.” These colors can be added as powders or larger bits to produce elaborate, multi-colored saturated hues, or as very thin overlays to produce more homogenous color.
The ability of glass to go from a molten liquid to a rigid solid in minutes allows artists to freeze motion in space, giving patrons the chance to visually linger over shapes that are typically only available to the human eye for an instant. Glass is unique in that its material properties allow artists to sculpt with vibrant transparent and opaque color in three-dimensional space, while filling in the voids with optically transparent material. Consequently, many glass-blowing techniques have been invented and practiced for thousands of years to take advantage of glass’ unique properties.
Pencil-like glass rods with spiraling colors inside of them are fused together on a pastorelli for an ancient Italian glass-blowing technique called zanfirico.
One of these techniques, zanfirico, involves laying out glass pencil-like rods and rolling them onto the end of a steel straw to form an open cylinder. The cylinder is re-heated, and the open end is pinched shut to form a balloon-like vessel on the end of the straw. The size of the vessel can then be enlarged by blowing into the straw to inflate the balloon. For a technique called reticello, two of these types of vessels can be combined together to trap tiny bubbles in between each of the rods for a lacey geometric pattern. These ancient Italian techniques will be demonstrated as part of the Mini Maker Faire at COSI using a mini glassblowing studio, about a tenth the size of a typical studio, on Saturday, September 29, 2012.
