When you’re new to fused glass, you might assume that everything goes in the kiln and comes out flat and shiny—but that’s only part of the story. The beauty of glass fusing is that you have options depending on the look, texture, and function you’re going for. Three core techniques—tack fusing, full fusing, and slumping—offer very different results. Let’s explore what they are and when to use each one.
What Is Tack Fusing?
Tack fusing involves heating glass just enough so that the layers stick together but keep their individual shapes and texture. The edges soften slightly, but the overall design remains raised and dimensional.
Why use it?
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Adds texture and depth to your design
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Great for decorative art, jewelry, and pieces where dimension matters
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Often fired to around 1350°F–1400°F
What Is Full Fusing?
Full fusing takes the glass up to a higher temperature, usually around 1450°F–1500°F. At this point, the glass layers melt together into a single smooth piece with no texture remaining.
Why use it?
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Creates a unified, flat surface
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Ideal for functional items like coasters, plates, and pendants
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Useful when you want clean lines or layered colors to blend
What Is Slumping?
Slumping is a technique used after fusing. You take a fully fused piece and fire it again over or into a mold so it takes on a new shape—like a bowl, dish, or curved panel.
Why use it?
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Turns your art into functional forms
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Adds curves and structure without changing the fused design
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Typically fired at a lower temperature (1200°F–1300°F)
Which Should You Choose?
That depends on your goals!
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Want a piece with depth and tactile design? Try tack fusing.
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Need a flat, clean finish? Go with full fusing.
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Want to make a dish or something sculptural? Slumping is your next step.
A Few Quick Tips:
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Use firing schedules that match your specific glass and project size.
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Make test tiles to see how your glass behaves at different temps.
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Combine techniques—full fuse first, then slump later.
Understanding these techniques gives you more control and opens up creative possibilities. The best part? You don’t have to choose just one. Let your ideas lead the way.
Got a favorite technique? I’d love to hear about it!