Few things are more satisfying than the process of glass firing art. From choosing the right type of glass, to methodically cutting your glass, and then programming the right firing schedule, glass firing is an intricate process. But it’s extremely rewarding to see your idea become a reality!
Today we’ll be covering the ins and outs of glass firing art – from planning and preparation, to perfecting your kiln formed glass techniques, to unloading your glass kiln. Plus, we’ll be sharing examples to help inspire your next project!
9 Steps for Glass Firing Art
Compared to other kiln fired media, glass firing requires extreme precision. There is very little margin for error – and preparation is key. However, don’t be intimidated! It’s ok to make mistakes.
Experimentation is part of the process – but reading articles like this can help you reduce the learning curve, avoid common pitfalls, and navigate the glass firing art process with more confidence! Additionally, if you’re a newer artist, it can be extremely helpful to take classes at a local studio and to seek out Facebook Groups like Fused.Glass or Fused Glass Fanatics, forums like WarmGlass.com or , and Subreddits like /r/fusedglass or r/GlassFusing where you can ask questions and compare notes with more experience artists.
Step 1: Planning Your Glass Firing Art Project
Successfully firing glass art starts before you ever cut a piece of glass or fire up your kiln. Take the time to plan out your project. For newer artists, it might be helpful to create a true-to-size sketch. Decide what types of techniques you will need for your projects as well as the types of firing schedules you will need.
Step 2: Selecting Compatible Glass
The glass you choose to use will do more than impact the color(s) of your glass firing art project. It will also determine whether your glass fuses are successful! The different layers of glass for your project must be fusible with compatible coefficients of expansion (COE).
Step 3: Cutting Your Glass
After tracing the outline you want to cut directly into the glass, work slowly and carefully to cut each layer of glass into the appropriate shape. A good pair of glass cutters can make this process a lot smoother (no pun intended!) and help you cut with more precision. Additionally, investing in a tabletop glass grinder can help you further refine your glass pieces. After cutting your glass, carefully clean each layer to remove any debris prior to kiln firing.
Step 4: Prepping Your Glass Kiln
Nothing is worse than when your glass project melts to the inside of your kiln! In addition to ruining your project, then you’re stuck cleaning up your kiln. We recommend priming your kiln shelves with kiln wash (also known as shelf primer) or using fiber paper underneath your project – or, ideally, both! While some kilns use fiber brick to help prevent this, we still recommend priming the bottom of your kiln just in case!
Step 5: Assembling Your Project
While some glass kilns include features like front access that let you easily assemble your project directly inside your kiln, not all glass artists are so lucky! In that case, you will have to arrange your project on a kiln shelf and then slowly (and carefully!) slide your shelf into the kiln. Make sure your shelf is at least 1” from the kiln floor with at least 2” of clearance from heating elements and the walls of the kilns.
Step 6: Programming Your Glass Kiln Controller
One of the most important parts of successfully glass firing art is to correctly program your kiln controller with the correct firing schedule for your type of project – and then having a precise process controller to successfully carry out that schedule.
TAP Kiln Controllers by SDS Industries are designed to make it easy to precisely and consistently program your glass kiln controller with easy-to-use touchscreen control, intuitive menus, and the ability to save an unlimited number of schedules so that you can easily repeat successful firings for different types of projects. Additionally, TAP Kiln Controllers use PID-driven control algorithms to automatically execute your schedules with maximum precision – with alerts, alarms, push notifications, and remote monitoring kiln control capabilities via TAP Kiln Control Mobile to give you more flexibility and consistency.
Step 7: Annealing Your Glass Art Project
It’s important to make sure you properly anneal your project. Most of the time, you can include an annealing phase right into the cooldown phase of your overall firing schedule (as pictured below!). Annealing glass involves holding your glass at a steady temperature to allow the glass to stabilize and strengthen (COE 90 glass is typically annealed at 900°F). Then, you control the cooling to ensure that your glass project doesn’t experience thermal shock.
Annealing ensures that the crystalline structure of the glass is stabilized to prevent cracking, protecting your piece from breakage due to stress (which can happen suddenly but also further down the road if your project isn’t annealed correctly).
Step 8: Unloading Your Kiln
After annealing, it’s time to unload your kiln! Unloading your kiln should be done after your glass firing art project has cooled down to room temperature. Unloading your kiln (or even opening the lid to sneak a peek) before your piece has properly cooled can lead to breakage and cracks from temperature-induced stress. Even though your kiln should be at a safe temperature, safety precaution is key! We recommend using heat resistant gloves to carefully remove your project from the kiln while being mindful of sharp edges that may result from your glass firing (or even broken glass if your firing failed). Additionally, we recommend making a habit of vacuuming out your kiln so that small particles of glass that may be left behind don’t melt to your kiln or mess up your next project.
Step 9: Learning and Improving with Each Project
Finally, as we mentioned earlier, it’s important to understand that mastering glass firing is a process of iterative improvement. After completing your glass firing, it’s important to assess how your project turned out – to build on what went right or improve on what went wrong. Many artists keep a kiln notebook to document the outcomes of their glass firing art projects. If your firing was successful make sure to save the schedule so that you can replicate it in the future – or, ideally, you can save it directly to your controller so that you avoid the hassle of having to flip through your notebook to find your schedule or risk user error when reentering it into your controller.
Different Techniques for Glass Firing Art
One of the exciting things about glass firing art is how many different techniques there are to choose from. Different kiln formed glass techniques can be combined to create unique, one-of-a-kind glass art pieces.
These glass firing techniques include:
- Full Fuse: Layers of glass are heated up until they liquefy and completely merge together, cooling to form a single, smooth piece of kiln formed glass. Full fusing can be used to create unique and beautiful color combinations. A full fuse for 90 COE glass occurs between 1450°F and 1490°F.
- Contour Fuse: Layers of glass are heated up enough to fully join together while remaining distinct separate layers, getting hot enough to lose some of their initial shape and become smooth at the edges. A contour fuse for 90 COE glass occurs between 1400°F and 1450°F.
- Tack Fuse: Pieces of glass are heated up just enough to join together at the point of contact, while still retaining their original shape – used to create new textures or shapes. A tack fuse for 90 COE glass occurs between 1350°F and 1400°F.
- Glass Drape: A sheet of glass placed over a convex mold is heated up until it at least partially melts and drapes around the mold. Higher temperatures produce more dramatic results. Glass draping can be used for a wide range of effects – from creating conventional plates and bowls to producing abstract shapes. To drape 90 COE glass, you need to heat it up to 1200°F.
- Slumped Glass: A fused piece of glass is placed inside a concave mold and heated up until it partially melts to take on the shape of the mold. Since slumped glass occurs within the mold, it leads to more predictable results, and is used to create plates, bowls, cups, or decorative molds. To slump 90 COE glass, you need to heat it up to 1265°F.
- Glass Casting: Enough glass is placed within a concave mold to completely fill the mold when it is melted. Once cooled, the glass anneals into a solid object in the shape of the mold. This technique is used to create ornaments, paper weights, and standalone glass art. Glass casting for 90 COE glass occurs around 1525°F.
- Glass Crackle: A decorative glass firing art technique that typically involves fusing together three layers of glass and shattering the middle layer in a controlled method. This effect can also be created by using glass frit and fiber paper to create a cracked effect – or using distilled water and glass powder. After the three layers are fused together, the outer layers are smooth, while the middle layer is crackled. For glass crackle of 90 COE glass, the layers should be fused together at 1410°F.
- Pot Melting: Pot melting is a decorative glass firing technique that involves allowing glass to melt through a hole in the bottom of a pot – onto a primed kiln shelf or into a contained mold – to create swirls and ripples and other textured effects. This video from our partners at Delphi Glass is a good example of this technique. For pot melting 90 COE glass, you need to heat it to 1600°F and hold for about an hour to get the glass to liquefy.
- Fire Polishing: Fire polishing is a “finishing” technique. Typically used after coldworking glass, the glass is then heated up until it returns to its original shiny and smooth state. Fire polishing for 90 COE glass occurs at 1350°F.
- Bubble Squeezing: A bubble squeeze is a “preparatory” technique used during firing, which creates a more even, structurally sound fuse by slowly heating up glass to allow trapped air to escape. Bubble squeezing for 90 COE glass occurs between 1200°F and 1225°F.
- Annealing: Annealing is a controlled cooling process that protects your project from thermal shock, breakage, shattering, stress fractures, and structural weakness. Annealing for 90 COE glass occurs at 900°F.
You can read about these glass firing techniques more in-depth in the following articles:
- Exploring 9 Different Kiln Formed Glass Art Techniques (Plus Examples!)
- Tips, Tricks, and Glass Fusing Techniques [Plus Examples!]
Examples for Glass Firing Art
Below are different examples of glass firing art projects to help inspire your next projects.
Using Glass Fuses to Create Illustrative Scenes
You can use glass fusing to create illustrated scenes and compositions that blur the line between glass firing art and painting! Remember, there are three different types of glass fuses – full fuses, contour fuses and tack fuses that each have different textural effects.
In the illustrated scene below, artist Mary Burke uses full fusing and glass frit to create the smooth background patterns for the sky and the ground, while using tack fuses to give depth and sharp outlines to the flowers, plants, and cacti in the foreground.
However, for functional pieces, such as the plates below, the sharp edges of a tack fuse might not be ideal. The contour fuses in the example below still give the illustration texture and depth, while the higher glass firing temperatures for contour fusing smooth out the rough edges.
Using a “Freeze and Fuse” Technique to Make 3D Art
“Freeze and fuse” is a glass firing art technique that combines glass casting and fusing techniques to create intricate three-dimensional shapes like the flowers Barbara Elias created below. To create these flowers, Barbara took wet powder glass (or glass frit) and packed it into a mold, then covered it with a towel before freezing it. After the glass frit froze completely, Barbara popped the glass out of the mold and then glass fired it until the glass frit fused together in the shape of the mold.
She then tack fused these flowers on a sheet of glass to create the composition below.
You can read this article to learn more about how to execute “fuse and freeze” techniques.
Using Slumping and Casting to Create Functional Pieces
One of the cool things about glass firing art is that you can use it to create pieces that are purely functional or purely decorative – or a combination of both! Additionally, you can often use different techniques to achieve similar results.
In the example below, Jill Gary (another artist who uses TAP for her glass firing!), used full fuses to create the colored patterns for her piece below – and then used a slumping technique to melt the glass into the shape of a bowl.
However, glass casting can also be used to create cups and bowls like the example of a piece I made several years ago (my own experiences as a glass artist served as inspiration for the TAP Kiln Controller!). To create this piece, I first designed the shape of the bowl with wax, and then created a mold around the object with a 50/50 mix of plaster and silica. Once the mold was set, I steamed out the wax to create the final hollow mold, which I filled with glass frit and cast into the finished bowl.
Power Your Kiln with The Most Advanced Glass Kiln Controllers
When it comes to firing glass, choosing the right kiln controller can help you execute your glass firing art projects with more ease, precision, and consistency.
The TAP and TAP II Controllers by SDS Industries provide users with intuitive touchscreen controls, PID-driven precision, and the ability to name, save, and access and unlimited number of firing schedules with an unlimited number of steps. The even include features like cost tracking and preventative maintenance to make managing a glass art studio easier!
With integration to the TAP Kiln Control Mobile app, you will be able to monitor your projects in real-time, receive real-time alerts, and enjoy remote kiln control through your smartphone or tablet!
We invite you to explore our selection of programmable kiln controllers, standalones, and conversion kits on our online store. You can also purchase TAP Digital Controllers or TAP Controlled Kilns and Heat Treat Ovens through one of the following distributors:
- Evenheat
- Hot Shot Oven & Kiln
- Mobile Glassblowing Studios, LLC
- Jen-Ken Kilns
- Kiln Frog
- Sheffield Pottery
- Delphi Glass
