What Is Glass Fusion? A Beginner’s Guide to the Magic Art of Melting Glass Together

What Is Glass Fusion? A Beginner’s Guide to the Magic Art of Melting Glass Together

Hot Shot Oven & Kiln

In case of emergency, break glass. In case of creativity, melt it!

The art of melting, or fusing, different pieces of glass together opens up a world of exciting possibilities for hobbyists, from functional to decorative to artistic. Heating up glass until it melts might seem like a simple process, but there’s plenty to learn, think through, and experiment with.

So if you’re interested in trying out the mesmerizing craft of glass fusion, we’ll walk you through all the basics you need to know in this beginner’s guide.

Glass Fusion Definition

Glass fusion, also known as kiln-formed glass or kiln casting, is a glass working technique that involves melting and fusing multiple pieces of glass together in a kiln.

Glass Fusing vs. Other Glass Crafting Techniques

Glass fusing is a distinct technique. The temperatures involved are not quite as high as those of glass blowing, where you shape molten glass using a blowpipe and other tools; or glass casting, in which you pour molten glass into molds to make solid, 3D pieces.

Meanwhile, unlike stained glass, you don’t use lead or copper to hold your different colored glass pieces together since you’re physically fusing them.

applications of glass fusing

The Wonderful World of Glass Fusing Applications

Glass fusion’s versatility and accessibility make it a popular craft. Hobbyists around the world enjoy fusing glass pieces to make a wide variety of beautiful forms, including:

  • Bracelets, pendants, and other jewelry
  • Picture frames
  • Coasters and plates
  • Bowls and vases
  • Candle holders and other home decor
  • Sculptures and wall art

Here are some more great fused glass project ideas. What’s your inspiration? There’s a good chance you can bring it to life by fusing glass!

hobbyist sitting in glass fusing studio

What You’ll Need for Your Glass Fusing Workspace

When you’re working with glass pieces and a kiln, you need to be careful. To reduce your risks, you’ll want a good-size, well-ventilated workspace. In other words, don’t try using a walk-in closet for your glass fusion studio.

Tools and Equipment

You don’t need a lot of equipment for fusing glass, but you will need:

  • An oven suitable for glass fusion: Look for a kiln with good safety features and easy-to-use temperature control. Hot Shot glass working ovens, for example, come with Cool-Touch technology to keep you safe, as well as precise temperature control to help you get great results. Built in the USA, our ovens are available in a range of sizes to suit your needs and space.
  • Glass cutting tools: Cutters, running pliers, and breaking grozers help you get your different colored glass pieces into the sizes and shapes you want.
  • Safety gear: Be sure to wear protective eyewear, clothing, and gloves whenever cutting glass or using the kiln.
  • Kiln shelves and molds: Various accessories are helpful to support and, for certain fusing techniques, shape your glass pieces during the firing process.

samples of glass fusion materials
Image Source: shop.bullseyeglass.com

Glass Selection and Preparation

It would be cool if you could just fuse any old pieces of glass you have around the house. But that isn’t quite the case.

For starters, you’ll find that most glass is fusible only if it’s within a thickness range of about 1/8 to 3/8 inch. Ultimately, the right thickness depends on your preferences as an artist as well as your specific project requirements. On the thinner side is good for smaller pieces and projects that prioritize transparency and delicacy. You might want glass on the thicker end for greater structural integrity and dimensional stability.

Bullseye, Spectrum, Uroboros, and Wissmach are among the most popular and trusted brands of fusible glass. From any of them, you can find a tremendous array of sheet, stringers (spaghetti like strands), confetti, and millefiori (small beads with colorful patterns) glass. They come in different textures, sizes and special tones including dichroic, with a unique color-shifting appearance.

Whatever fusible glass you acquire, keep in mind that your glass pieces must be compatible to fuse together. Incompatible pieces are prone to shattering during processing or developing fractures later in use. And that issue brings us to the following question:

What is the Coefficient of Expansion (COE)?

COE refers to how much a glass expands or contracts with changes in temperature. For effective fusion, you need pieces with the same COE to prevent cracking or breaking.

For example, Spectrum System 96 is a popular line of fusible glass products. As you might guess, they’re all at COE 96, and they come in a wide array of colors and textures.

Cutting Glass Pieces

Glass cutting is an essential skill for glass fusing. If you don’t have any experience, practice cutting different shapes and sizes. Learning how to cut glass takes some patience. But even mistake cuts in practice can lead to an interesting or unexpected design feature if you keep an open mind.

The Importance of Clean Glass

Cutting and working with glass can leave dust and dirt on the pieces. And these particles make it hard to end up with a smooth, defect-free finished product. Always clean your workpieces with detergent and allow them to dry before fusing. No fingerprints should be visible on your workpieces.

The Fusing and Annealing Process

With your glass selected and your pieces cut and cleaned, it’s time to assemble your design and start fusing!

Arrange your pieces on a kiln shelf in your desired pattern, color combinations, and dimensions. You can layer the pieces, varying colors and textures to create depth. Or incorporate other materials, such as metal foils, frits (crushed glass), or powdered enamels, to create interesting textures, color variations, or metallic effects.

Then heat the furnace up and hold or soak your creation at temperature for a set period. Your pieces will gradually soften and melt together. Glass fusion firing profiles can range from 1250°F to 1500°F for up to an hour. Your specs will vary by project, depending on the fusing technique you’re going for (more on those in just a moment), the thickness of your glass, and other factors.

After fusing comes annealing: slow, controlled cooling to relieve internal stresses and strengthen the glass. Annealing glass is typically done at around 950-960°F, for a minimum of 1 hour.

A Look at the Basic Glass Fusion Techniques

The craft of fusing glass encompasses a range of processes with different purposes, involving different temperatures, heating cycles, and durations:

Full Fusing

Working at the highest glass fusing temps of 1450-1500°F allows the glass to become fully fused together. The result is a smooth surface, without any texture.

Tack Fusing

At the low end of fusing temps, 1350-1370°F, the glass will stick together but hold its edges and shape.

Glass Slumping

Working in the range of 1200°F to 1300°F, slumping involves shaping glass into beautiful and functional items. You heat it just enough to bend or “slump” into ceramic or metal molds. Use this technique to make plates, bowls, decorative art, and other dimensional objects.

Pattern Bars and Glass Combing

Several techniques can achieve distinctive effects.

For example, in a technique often called pattern bars, you arrange glass pieces of different colors and patterns into a solid block. After fusing, slice the block into cross-sections, revealing intricate patterns and designs.

In glass combing, meanwhile, you drag a comb or similar tool through layers of molten glass, creating fascinating swirls, lines, or waves.

Finishing Touches for Fused Glass

Once the glass has cooled, you can shape or add special surface finishes to your piece if you want. Use cold working techniques such as grinding, polishing, or sandblasting to refine the edges or textures of your glass.

Glass fusion artist examining workpiece

Glass Fusion Tips & Troubleshooting

Here are a few additional pointers to keep in mind as you explore glass fusion:

  1. Do compatibility testing. Even if you’re working with pieces with the same COE, testing things out can help you avoid unwelcome surprises. Create small test pieces with the glass combinations you intend to use and fire them to see if they fuse together without issues.
  2. Allow adequate annealing time. Don’t skimp on annealing, which is essential to preventing cracking or breaking due to thermal shock. Follow recommended annealing schedules for the type and thickness of glass you’re using.
  3. Help prevent devitrification. Crystals can form on the surface of your glass, resulting in an unwanted cloudy appearance. To avoid this issue, make sure your fusing glass is compatible, be careful not to overheat, and follow proper annealing methods.
  4. Do your research. Take advantage of the wealth of resources available to enhance your knowledge and skills. Check out glass fusion books at your local library. Look up online tutorial videos. Take a class. Join a local glass art community.
  5. Experiment and have fun! Glass fusion can be a rewarding and creative hobby, but it requires patience, practice, and play. Start with small projects and gradually expand your skills and techniques as you gain confidence. Enjoy the process of exploring the limitless possibilities of fused glass art!

Got questions or need help choosing the right oven for glass fusing? Contact the experts at Hot Shot Ovens today.