How To Fuse Glass

Simple Fusing Instructions

Fused glass is one of the easiest and most exciting techniques for beginners.

There’s lots of things you can make with it… jewellery, plates, coasters, sun catchers, clock faces… or small windows and panels for your home.

There’s also many different creative things you can do. You can fuse it flat or with a texture. You can mix big shapes with small bits of glass frit. There’s gold mica powders, decals and iridescent surfaces. You can create bubbles, add wire, use stencils. The list is endless.

What is fusing?

– Fusing is heating two or more pieces of glass in a kiln so that they melt together.

– The temperature for melting glass is from 1400F/760C to 1500F/815C.

The top heat depends on what type of glass is being fired, and what result you’re after.

Imagine you’re making a landscape panel like the one above. To keep the texture on the hills it’s important not to melt it too much. This panel was fired at the lower end of the fusing heat scale. This is called a ‘tack fuse‘.

A higher temperature would be used if you wanted it smooth – for example for a coaster. This is called a ‘full fuse‘.

Before You Start

Fusible glass

The type of glass that you use for fusing is very important. It has to be glass that won’t break when it’s heated up and cooled down in the kiln.

Sadly this means that all your leftover bits from other projects will probably not be suitable for fusing.

All the pieces have to be compatible with each other for successful fusing.

Called ‘Fusible Glass’, the most popular ranges are made by Bullseye and Spectrum . Spectrum call their fusing range ‘System 96’.

Glass behaviour when heated

The best thickness for fused glass is 1/4inch (6mm).

If you fired one square piece of 1/8 (3mm) sheetglass in a kiln the edges would shrink in and it would no longer be exactly square.

Fire three layers (3/8inch/9mm) and the square would become rounded and bigger as the volume of glass melts and pushes outwards.

Two layers? Perfect. The glass stays the same size and is square.

What You Need

A selection of fusible glass, pattern, glass cutter, grozing pliers, detergent cleaner, safety glasses, dustpan and brush, access to a kiln.

Optional: a grinder

How To Fuse Glass

If you’re a beginner it would be best to start with something small and easy. Coasters are a good idea. Keep in mind that two layers are best, and design something to suit.

It’s a good idea to lay the shapes underneath a top layer to make sure you get a flat surface. This is called ‘capping‘.

If you have the smaller shapes on top, you might get some texture where they meet.

1. Designing

– Draw a square – say 4 inches (10cm) on a piece of paper.

– Sketch your ideas inside the lines.

– Keep it simple, especially if you’ve never cut artglass before.

– Don’t worry too much at this stage about getting it perfect. At this point it’s more about learning about how the glass behaves in the fusing process and getting the hang of each step.

– If you don’t feel able to design something yourself, then there’s some free patternshere that might get you started.

2. Cutting and cleaning the artglass

– There’s a whole page on how to cut glass here, which takes you through each step. It includes drawings, photos and a video to help you.

– Once you’re happy that you’ve cut everything to size, clean each piece with detergent, and dry.

– Any oil or fingerprints will be permanently fired if you don’t do this thoroughly.

3. Loading the kiln

– Put the coasters in the kiln, either on Bullseye thinfire ceramic fiber paper, or on a kiln shelf painted with batt wash.

– These act as a separator and stop the glass from sticking to the shelf.

4. Kiln firing schedule

Be aware that this program can only be a starting point, as each kiln has its own character and behaves differently.

It is a generic schedule for a full fuse on two layers of artglass up to 1foot square (30cm sq).

Segment 1 – Heat the kiln up at around 400F/222C per hour to 1100F/600C

Segment 2 – Slow the heating rate down to around 200F/111C per hour. This helps prevent bubbles trapping between layers.

Segment 3 – Hold the temperature at 1240F/670C for 30 minutes. Don’t bother with this soak if you want bubbles.

Segment 4 – Fire as fast as possible to 1480F/804C.

Segment 5 – Soak for 10 minutes.

Segment 6 – As fast a possible to annealing temperature recommended by manufacturer ( 900F/482C for Bullseye, 950F/510C for Spectrum)

Segment 7 – Hold at annealing temperature for 30 mins.

Segment 8 – Cool to room temperature at around 200F/111C per hour.

5. When can I open the kiln?

Impatience has cracked many a masterpiece!

It’s best to wait until the kiln reaches room temperature, but you can hurry it along a little by ‘cracking’ the kiln (opening the door a little) at about 200F/90C.

This isn’t advised if you have anything complicated in the firing, for example extra thick pieces, wire or copper sheet.

6. Cleaning your work

Only wash the piece once it has reached room temperature. The water will cause thermal shock otherwise.

Helpful Resources

This is a good video explaining the fact that glass likes to be 1/4 (6mm) thick. It also helps understand how it behaves in a kiln.

Video showing how glass volume spreads in kiln

If you want to slump your fused piece, then go to the Slumping page.