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What do you get when you mix sand, soda and lime together, and heat it to about 2500°F?

You get the spectacular stained glass of Notre Dame, breathtaking Byzantine mosaics, Tiffany windows and lampshades, Murano glassware, Dale Chihuly chandeliers, and much, much more.Byzantine Mosaic in Ravenna Italy, 6th CenturyByzantine Mosaic in Ravenna Italy, 6th Century

Mosaic from PompeiiThese world renowned works of art are all made of soda-lime glass, a very ordinary material easily made from quite common ingredients. At least at the beginning. But craftsmen have now had some 6500 years to play with it, and have cut it, bent it, fused it, ground it, fractured it, stretched it, spun it and otherwise transformed it into a never-ending parade of astonishingly beautiful functional and decorative items.South Rose Window, Notre Dame Cathedral, 1260South Rose Window, Notre Dame Cathedral, 1260

The glass arts these days are often broken down into 3 major groups -- cold glass, warm glass and hot glass -- although techniques from any or all of these categories can be used in any one project.

Cold glasswork is that which is done when the glass is somewhere around room temperature -- techniques include cutting, etching, sandblasting, polishing, and so on -- finished cold work art includes stained glass, mosaics, cut glass (think Waterford) and similar items.

Warm glasswork refers to techniques and finished works that involve use of a kiln and temperatures from 1100 - 1700°F. For the most part, artisans working "warm" use existing glass in a variety of forms -- sheet glass, crushed glass, rods, etc. -- and use the heat of a kiln to reform and reshape the glass. Jewelry, many dishes, decorative panels, and components for other works of glass art are created in this way.

Hot glasswork is the province of glassblowers , lampworkers (aka torchworkers) and glass casting craftsmen who work with glass at temperatures from 1700 - 2000° and higher. Glassblowers gather molten glass on a long pipe, and form vases, bowls, platters, glass ornaments, lampshades and other items by blowing air through the pipe. Lampworkers use various types of torches to melt smaller amounts of glass and form beads and other jewelry components, small sculptural items, paperweights, small vases and ornaments and the like. Glass casting includes various techniques of directing molten glass into a mold, then allowing it to cool into the shape of the mold.

About Glass

The type of glass used in a particular project is critical, for the simple reason that there are many different types of glass, and they don't all play together nicely.Blown Glass Vessel by Lino Tagliapietra, 2006Blown Glass Vessel by Lino Tagliapietra, 2006

Artisans who create cold glasswork have the fewest restrictions -- as long as the glass meets size, color, and texture requirements, it can be incorporated into a project.

Once glass is heated enough to change shape, usually around 1100°F or so, the type of glass used is much more critical. That's because different types of glass contract and expand at different rates as they are heated, which can cause the glass to break as it cools down. Some glasses become viscous at different temperatures, which can cause inconsistencies in the design. And there are many color groups of glass that have components that chemically react with other color groups at higher temperatures.

 Other characteristics of glass come into play as the temperature goes up. Some colors can't take as much heat as other colors, and while some colors can be taken to high temperatures many times, other colors will darken or become dull if they are heated multiple times.

The Challenges of Making Glass

Apart from the special characteristics of each type and color of glass that is used, just heating any glass to high temperatures can create issues. If you heat it up or cool it down too fast, it will break. While glass is typically "amorphous," meaning it has no crystalline structure, multiple firings and certain conditions can cause it to "devitrify", or develop a crystalline structure on the surface. This could make the finished piece hazy or appear to have scum on the surface. Additionally bubbles already in the glass or that form as the glass is heated can cause a variety of structural and other issues.

In addition to understandiGlass Bead by Patti Walton Glass Bead by Patti Walton ng the physical and chemical properties of glass, it's important to add that working with glass in any form can be hazardous. Minor cuts, imbedded shards of glass, and major lacerations are the most obvious, but inhaling glass dust or powder can have serious respiratory implications. And working with glass typically entails the use of tools, equipment and chemicals that have their own risks. As beautiful as it is, there is a cost to the magic created by glass.

How Glass Artists Work

Every artist has his or her own ways of working -- from how they organize their materials, to the arrangement of equipment, to the storing, marketing and displaying of finished works. Many cold and warm glassmakers work out of their homes -- some use the kitchen table as their main workspace, while others have multi-room studios complete with kilns, torches, glass grinders, saws and other power equipment, and a full range of hand tools, copper, silver and gold foil, ceramic molds, kiln furniture, and more.Kiln-Cast Glass Sculpture by Sue Hawker, 2008Kiln-Cast Glass Sculpture by Sue Hawker, 2008

Having space at home though, does not preclude trips to larger studios. Commercial studios often have larger, more efficient equipment that would not be practical in most residences.

Hot glass artists are more likely to work out of a studio, if for no other reason the power required to run the furnaces that supply the molten glass. Many of the larger torches require oxygen, propane or other gasses that can be hazardous to store. Glassblowers in particular need a fair amount of space... manipulating a ball of molten glass on the end of a four-to-five foot glassblowing pipe in tight quarters is not recommended.

How to Get Started Working with Glass

The best way to begin working with glass is to take classes. Many studios, community colleges, and art studios offer beginning level classes in virtually every category of glassworks; and there are increasing numbers of intermediate and master classes available.

There is also a considerable amount of written material, including much that is online and free-of-charge, that provides important technical information as well as expert advice for every level of glassworker.

For most types of glasswork, the first and most critical technical skill is cutting glass, or more accurately, scoring and breaking glass with any of a variety of tools. Learning to operate power equipment such as glass, belt and lap grinders, tile, band and glass saws, sandblasters, and Dremel-type tools can be exceptionally helpful. Learning to safely use kilns and torches is critical for those who like their glasswork hot.

Fused Glass Bowl by Martin Kremer, ca 2010Fused Glass Bowl by Martin Kremer, ca 2010
A reasonable amount of dexterity is required, especially for works that incorporate small pieces of glass, as is an appropriate concern for personal safety. There is always risk working with glass and its associated tools and equipment, but following relatively simple safety precautions -- such as using eye protection and face masks, wearing closed shoes and following the directions for equipment and use of chemicals -- can dramatically reduce the risk of both annoying and serious injuries.

This is Not the End...

There is so much more!  Stay tuned for more articles about the art and craft of glassmaking, by Emily Pezzulich ©2012