Glass is an extremely versatile medium that can be used to create items that span a wide variety of applications. Functional glass objects are so common in our everyday lives that we may not even think about how much rely on this material. Windows, smartphones, medical equipment, drinkware and a million other things we interact with daily fall into this category. On the other end of the spectrum, glass can make for beautiful and unique decorative art pieces. There are so many ways to manipulate glass into different shapes, textures and colors allowing for limitless creative options. This post will take a look at the various types of art glass and show some of the amazing artwork that can be created through each technique.
Glass art by Lino Tagliapietra
Temperatures of Glass
The techniques used to manipulate glass can be divided up into three categories based on the temperature of the glass that is being worked. Hot glass is kept at a temperature of 1100-2000°F (593-1093°C) and is differentiated by the use of a direct flame. Warm glass techniques involve the use of a kiln heated at 1099-1501° F (592°-816°C). These processes are relatively hands-off and rely on the use of heat, gravity and molds to melt and shape sheets or rods of glass, leaving a bit more to chance. Lastly, cold glass techniques are done with room temperature glass. These are typically processes that are done to finish up a piece such as sandblasting, engraving, grinding or polishing.
Types of Art Glass
Hot Glass Techniques:
Glassblowing is one of the most popular techniques used to create art glass. It requires a set-up like the one we have in our studio, which includes a furnace, re-heating chamber, annealer and a workstation. The furnace holds the molten soda-lime glass and keeps it at a working temperature. This furnace is kept on 24/7/365 because it takes so long to get the glass to the correct temperature. The reheating chamber is used to reintroduce heat into the glass while it’s being worked on. Glass cools down and hardens fairly quickly, so it is necessary to continue adding heat to it to keep the material malleable. The annealer cools down the glass slowly over several hours. If glass cools down too quickly, it can experience thermal shock, causing it to crack. Placing it in a slow cooling annealer over several hours helps to prevent this. Finally, the workstation that glassblowers use is the bench. Glass is gathered on a blowpipe or pontil rod and brought over to the bench to be manipulated using various tools. This setup is generally quite large (we have one of the largest glass studios in Michigan!) but it can be scaled down and even made portable. Watch this video to see a mobile glassblowing studio in action!
Glassblowing is so popular because it allows the artist to work very closely with the glass and to manipulate it in a variety of ways at each stage of the process. Glassblowing of course consists of using a blowpipe to blow air into a gather of glass, creating spheres or other hollow shapes. Other techniques such as hot sculpting allow for glass to be worked as a solid mass. Frit and cane can be added to clear glass to add further variations in colors and patterns. The pieces above illustrate the the incredible variety that can be achieved in shape, size, color and texture through the process of glassblowing. Get a more in depth look at our studio setup and the basics of glassblowing in our Glassblowing 101 blog post! See an example of the glassblowing process in this videoof April making one of the signature epiphany wine decanters.
Flameworking involves using a gas torch to melt glass tubes or rods into a molten state and manipulating them into different shapes using tools, hand movements and blowing. There are many similarities to glassblowing, but flameworking uses a torch as it’s primary source of heat and is done on a smaller scale, typically with borosilicate and soda-lime glass. A great deal of control is possible using this process, allowing for the creation of small and detailed objects. Some items that are made with flameworking include small pieces of art, small vessels and goblets, beads, marbles, ornaments, figurines and pendants, just to name a few.
Here’s a remarkable video from the Corning Museum of Glass that briefly shows the process of flameworking and how detailed and intricate these pieces can be.
Glass casting involves putting molten glass into a mold and letting it solidify. There are many different techniques and materials that can be utilized. Lost wax casting, a technique that has been around for thousands of years, is commonly used to create a mold for casting. Lost wax casting starts out with making a positive sculpture out an oil-based clay. A mold is made from the clay using material such as alginate. Once this mold is crated, wax is poured in to create temporary wax sculptures. The wax sculptures are then put into plaster. Once the plaster is hardened, the wax is melted to leave an empty mold. This mold can then be filled with molten glass or pâte de verre, which is discussed below. You can learn more about lost wax casting at this link!
Pâte de verre
Pâte de verre is a specific type of glass casting. It is a a process in which finely crushed glass, the consistency of sand, is made into a paste with the addition of a binder such as gum arabic. This paste is put into a mold, which is then placed in a kiln. The glass particles fuse together to become a solid piece. You can see from the above examples that påte de verre can pick up a high level of detail dependent on the mold it is placed in. It can also be used to create vessels with a grainy or sugary appearance or to add bas relief to other objects.
See how the cabbage leaves above were made by Kimiake Higuchi in this video from Corning Museum of Glass!
Warm Glass Techniques:
Glass fusing involves placing two or more pieces of glass next to another and putting them in a high temperature kiln. The glass melts and the pieces stick to each other, resulting in a larger solid piece. This allows for the creation of different color palettes and patterns as seen in the examples above. This is a very versatile technique and can be used on its own or in conjunction with other techniques, allowing for greater variation in what can be created.
Slumping is a process that uses heat and gravity. A flat sheet of glass is placed into a kiln on top of a mold and heated until the glass melts down into the mold. Molds can be made of materials such as ceramic, sand and metal and are coated with a release agent such as boron nitride, so the glass can be removed once it has melted to shape. The molds they are placed on can allow for a gentle curve in the glass or create dramatically shaped vessels in which the glass folds on itself and flows over the mold.
Fusing and slumping can be combined to allow for more variations in colors, patterns and shapes.
Watch this video to see the processes of fusing and slumping and how they can be used together.
Cold Glass Techniques:
Stained glass is made up of pieces of colored glass fit into an iron frame, called tracery, to make deigns or scenes, traditionally in windows. They are commonly found in churches and cathedrals but can also be seen in public places such as government buildings, educational places or banks. In modern times, stained glass has been extended to three-dimensional objects, such as objects d’art and the lamps created by Louis Comfort Tiffany (shown above). The colored glass for stained glass pieces can be made by adding metallic salts to the glass or by later applying paint and fusing the paint to the glass in a kiln. Stained glass windows often contain scenes that tell a narrative but modern uses can be more abstract or decorative. You can learn more about the history and uses of stained glass in this article.
The techniques discussed here are just a few of the endless ways that glass can be manipulated to create unique and beautiful visual art. Below are some other resources for you to learn more about art glass and the techniques used by glass artists!
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We frequently post videos and pictures of our own art glass!