Using a Pottery Kiln for Glass Fusing: Tips for Australian Makers

Australia has long punched above its weight in studio craft, from the etched glass workshops of the Blue Mountains to community studios in inner Brisbane. Many makers who already own a ceramic kiln wonder whether the same tool can handle fused glass, and the short answer is yes, with a few adjustments. Glass fusing opens a parallel world of jewellery, tiles, and decorative panels, and using a pottery kiln for the job lets you experiment without buying extra equipment.

Before loading your first sheet of glass, it helps to understand where pottery and glass-making diverge. Kilns built for clay reach higher temperatures than fused glass ever needs, so controlling heat becomes the main skill. Ventilation, shelf preparation, and a sensible firing schedule matter more than the brand of your kiln. A weekend spent reading glass compatibility charts and practising with scrap glass saves heartbreak later, especially if you sell at weekend markets along the east coast.

Preparing Your Pottery Kiln for Its First Glass Project

The first step is a deep clean. Dust, bisque grit, and stray glaze drops can fuse to your shelf or transfer onto glass, ruining an otherwise clean tile. Vacuum the floor and walls, wipe the elements gently, and replace any damaged soft brick. A ceramic kiln sitting in a garden shed in Adelaide or Perth through a long hot summer often needs this kind of attention before it will fire reliably.

A short prep checklist before every glass firing looks like this:

Ventilation matters too. Even though fused glass fires at lower temperatures, off-gassing from certain colours and kiln wash residue is unpleasant, so a window-mounted fan is a worthwhile investment, particularly in suburban home studios where neighbours may object to lingering smells. Apply a thin coat of kiln wash to every shelf that will hold glass. The wash keeps molten glass from welding itself to the shelf and makes cleanup far easier. Let it dry fully before firing, and recoat any bare patches after each project.

Choosing Glass and Molds That Work in a Ceramic Kiln

Not all glass behaves the same when heated. Fusers rely on a measurement called the coefficient of expansion, and pieces in the same firing should match closely. Mixing a COE 90 sheet with bottle glass pulled from a clean Coopers brewery line, for instance, will lead to cracking as the piece cools. Beginners are wise to start with single-brand starter packs from suppliers such as Bullseye or System 96, widely stocked by Australian online retailers.

Glass thicker than about six millimetres slumps unpredictably in a pottery kiln, so stick to standard 3 mm sheet for flat pieces and 6 mm for slumped bowls until you have run several firings. Moulds come in ceramic, stainless steel, and moulded fibre, all of which work provided they are clean and free of moisture. Many Adelaide Hills fusers use vintage metal cake tins, which slump nicely and cost almost nothing at a Saturday op-shop run.

Before committing to a final design, lay out your cut pieces on a primed shelf and photograph them. The Bellingen studio scene has popularised this habit, and keeping a folder of dry-layout photos becomes a reference library when you want to recreate a colourway months later. Makers who enjoy smaller hand-stitched pieces find a satisfying crossover, since a fused glass pendant complements a hand-made bracelet. Detailed guides exist for how to make a friendship bracelet with embroidery floss if you want to round out a handmade gift range.

Setting Reliable Firing Schedules

A pottery kiln has chunky controllers, often manual rather than fully programmable, so planning the ramp manually is part of the craft. A typical fuse-and-slump sequence for a 3 mm piece starts at around 100°C per hour up to 540°C, then climbs more quickly to the target top temperature before dropping through the cool-down band. Tape the schedule to the wall next to the kiln so anyone using the studio runs the same reliable firing.

Common firing targets for a 3 mm sheet in a small pottery kiln include:

Top temperature depends on the effect you want. Tack fuses land between 650°C and 700°C and keep the edges of the glass distinct, while full fuses above 740°C round the edges and merge everything into a single sheet. Slumping needs a slower final approach and a hold at slumping temperature for fifteen to twenty minutes. Writing these targets on a whiteboard beside the controller helps when several people share a studio, as is common in shared community spaces from Fremantle to Fitzroy.

Watch the kiln through a peephole or pyrometer window rather than lifting the lid. Opening the door during a fuse introduces a thermal shock that can crack the glass or skew colour results. If the kiln overshoots, resist the urge to fiddle; most controllers settle within a few degrees. Calibrate the pyrometer once a year, since workshops often run their kilns hard and drift is common after busy festive-season runs.

Annealing, Cooling and Finishing Touches

Annealing is the part many beginners skip and later regret. Glass must pass through a slow cooling band around 510°C so internal stresses can relax, otherwise pieces shatter weeks later when handled. Program a ramp down of around 80°C per hour from the top temperature to about 370°C, then let the kiln cool naturally to room temperature. Rushing this step turns beautiful work into expensive landfill.

Once cool, lift the piece carefully and inspect the edges. Sharp corners on jewellery cabochons can be smoothed with diamond hand pads, moving from coarse to fine. A quick buff with a soft cloth brings out the depth of colour, and a felt-lined tray is useful for transporting finished work to local markets or galleries. Many Australian fusers sign and date the back of each piece in metallic pen, which adds a personal touch buyers appreciate at Salamanca Place or Mindil Beach.

A winter evening at the kiln is not so different from an evening with yarn and needles, and makers who like to switch between mediums often keep a basket of small projects nearby. Some enjoy knitting fingerless gloves during long firings, then stepping back into the studio to lift finished pieces once they have cooled. It keeps the hands busy and creative momentum flowing.

Troubleshooting the Most Common Pitfalls

Devitrification, the cloudy white film on an otherwise glossy surface, is the most common complaint from beginners. It usually means the glass soaked too long at peak temperature or cooled too slowly through the devitrification band. A short return trip to around 700°C followed by a faster drop can sometimes rescue a piece, though prevention is always easier than repair.

Crazing, the network of fine cracks appearing weeks later, almost always points to incompatible glass. Check your scrap bin, photograph each project alongside the label of the glass used, and retire any leftover mystery offcuts to a mosaic jar. Stones or inclusions that trap moisture also crack work from the inside; dry everything thoroughly before loading.

Finally, keep records. A simple spreadsheet of firing schedules, glass brands, kiln position, and finished results pays dividends within a season. Australian fusing communities, from the Canberra Glassworks open studio days to informal Gather & Fuse meetups in regional towns, all rely on shared notes to push the craft forward. With patient preparation, an existing pottery kiln can become a dependable glass studio, expanding what you offer without adding much to your toolkit.