Looking for some clear directions to complete a glass fusing project? A glass fusing temperature chart is a good place to start.

Below, we’ve assembled firing schedules for a variety of glass fusion projects. After that, if you need a little help deciphering what these charts are all about, we’ll provide some additional background and context.

Let’s dig in!

Recommended Firing Schedules for Glass Fusing Projects

The following glass fusing temperature charts are meant as general guidelines for COE 96 glass. Your optimal parameters may vary based on COE, thickness, shape, and other factors. Consult your glass supplier to determine your best approach.

Tack Fuse Temperature Charts

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A tack fuse is ideal for creating textured glass of varying thickness. The different pieces fuse together, but they still retain their shapes and edges. Glass is soft enough to form a permanent bond, but the pieces still retain their shape and edges.

Jewelry Cabochons

Cabochons are small, round gems used for pendants, earrings, bracelets, etc. These are basically the smallest glass fusing projects you can take on.

Small Projects (up to 8 inches)

A picture frame makes a fine small project for tack fusing, with the resulting colorful texture calling attention to the image on display.

Medium Projects (8–12 inches)

Candle holders and other home decor make excellent medium tack fuse projects.

Large Projects (over 12 inches)

Large tack fuse project possibilities include dimensional wall art and sculptures.

This chart includes a slower second ramp up segment to eliminate air bubbles.

Full Fuse Temperature Charts

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In a full fuse, your glass pieces melt completely together and create a smooth surface (instead of retaining some shape and texture, as with tack fusing).

Jewelry Cabochons

A full fuse creates a beautiful, polished look for glass jewelry.

Small Projects (up to 8 inches)

The smooth surface created by a full fuse is ideal for drink coasters.

*If you’re fusing 3+ layers, slow the ramp rate to 300 °F.

Medium Projects (8–12 inches)

Try a colorful serving plate or other tableware for a medium sized full-fuse project.

*If you’re fusing 3+ layers, slow the ramp rate to 300 °F.

Large Projects (over 12 inches)

Go bigger with serving platters and bowls that feature a smooth, shiny finish.

This chart includes a slower second ramp up segment to eliminate air bubbles.

*If you’re fusing 3+ layers, slow the ramp rate to 300 °F.

A Look Inside the Numbers

The series of temps in the above firing schedules can be hard to sort through. How do you know the numbers are legit? What goes into determining the temperature ranges, and why? Now let’s explore some of the technical details of how to use a glass fusing temperature chart.

What’s in a Firing Schedule or Temperature Chart?

As you can see in the charts, it’s never as simple as just heating your kiln up to a target temperature. It always involves multiple phases (also called segments) of heating and cooling, including:

• An initial heating phase
• An accelerated heating phase to the target temperature
• A cooldown to annealing temperature
• A faster cooldown to room temperature

What’s Not Included?

A firing schedule or temperature chart is really just that: a series of temperatures to set for your kiln. It’s not a complete guide or directions. If you’re looking for more detailed directions, check out our beginner’s guide to glass fusion and our step-by-step guide to melting glass in a kiln. 

A Closer Look at the Phases

Glass fusing involves a series of carefully controlled steps. Here’s what a typical temperature chart covers and why:

Ramp Up

Glass expands as it heats.

If this heating and expansion doesn’t occur evenly, it creates pressure between the cooler, harder inside and the hotter, now softer outside. As a result, the glass tends to crack.

Your initial, slow ramp up phase is designed to prevent cracking by allowing the glass to equalize gradually.

For most fusing glass, the slow ramp up phase will aim for a key temperature for thermal shock safety: 1,000 °F.

At that point, you’ll hold at temperature long enough for the glass to fully equalize.

Heating to Fusing Temperature

Once your glass has equalized at 1,000 °F, you can accelerate the rate of temperature increase to get to your fusing temperature. Where you top out at depends on what level of glass fusion you want to achieve:

• Tack fuse – 1,350 °F – Glass is soft enough to form a permanent bond, but the pieces still retain their shape and edges.
• Medium fuse – 1,400 °F – Glass starts to flow together but isn’t completely fused.
• Full fuse – 1,450 °F – Glass melts completely together and forms a smooth surface.

Once you reach the target temperature, you soak the glass for a period to ensure you complete the fuse you want.

Cooldown for Annealing

Just as glass expands when heated, it contracts when cooled. If you cool it too fast or unevenly, you introduce a lot of stress that can lead to cracking.

That’s why the cooldown phase also must be careful—a process called glass annealing.

For annealing, the firing schedule typically calls for cutting the temperature down to ~960 °F and then holding it there.

Cooldown to Room Temperature

After the anneal hold, you drop the temperature slowly to what’s called the strain point: ~800 °F. That’s when the glass molecules have stopped flowing and the annealed condition is locked in.

The rest of the cooldown can proceed more rapidly.

Soak

Each of these segments includes a hold or soak time to ensure even heating and cooling and allow complete transformation in the glass fusing process.

Considerations That Impact Your Parameters

The parameters in a glass fusing temperature chart vary depending on a variety of factors.

COE

Coefficient of expansion (COE) is a critical factor in glass fusing processes. The COE of your glass tells you how much it will expand.

The higher the COE, the lower the temperature required for fusing. So if you’re fusing COE 96 glass, but you’re looking at a firing schedule for COE 90 glass, reduce the top temperature by ~20 °F.

Viscosity

Viscosity refers to a material’s resistance to flow.

The higher the viscosity, the higher the temperature you need to get your glass flowing and fusing together. High viscosity glass may also require longer soak times to achieve the effect you want.

Thickness

Keep in mind that thick glass pieces need more time to heat up and cool down than thin sections.

Most temperature charts are based on a common project thickness of ~¼ inch. To ensure the process does its job, you may need to add to the soak time at the fusing and annealing temperatures. You also may need to slow your ramp rates, particularly when fusing projects of more than two layers.

Your Kiln

Because careful control of temperature is essential to glass fusing success, a quality kiln counts for a lot.

Hot Shot glass kilns, for example, provide precise temperature control for fusing. Quality built in the USA and ready to ship in a range of sizes, our kilns will help you get great results in all types of glass fusing techniques.

Infuse Your New Knowledge into Amazing New Creations

Now that you’ve got more background knowledge about glass fusing firing schedules, it’s time for experimenting and advancing your skills.

Check out our glass fusing project ideas for inspiration, and let your creativity take your craft to exciting new heights!