Every glass artist has a unique vision. Some are drawn to deep, rich colors and intricate, structural designs, while others want to create pieces that pop with brilliant, eye-catching vibrancy. The path to achieving that vision starts with a fundamental choice of material. In the world of kiln-formed glass, that choice often comes down to COE 90 vs 96. These two systems offer completely different palettes and working properties. One isn’t better than the other; they are simply different tools for different artistic goals. Let’s explore the characteristics of each so you can confidently select the glass that will bring your creative ideas to life.
Glass art projects can be as diverse as the imagination allows, but choosing the right type of glass is crucial. For beginners entering the world of kiln-formed glass, two terms often encountered are COE90 and COE96. The differences may seem technical, but understanding them is essential for achieving the desired artistic results. This guide delves into these types of glass, discussing their properties, applications, and which might be the best fit for your project.
What Does COE Mean for Your Glass Art?
The Coefficient of Expansion (COE) measures how much a material expands when heated. For glass fusing, it indicates compatibility when different glasses are fused together. If the COE of used glasses isn’t compatible, it can lead to cracks as the piece cools.
| Type | Coefficient of Expansion (COE) |
| COE90 | 90 × 10-7 /°C |
| COE96 | 96 × 10-7 /°C |
The Science Behind the Number
So, what’s the big deal with these numbers? Think of the COE as a compatibility rating. It tells you exactly how much a specific piece of glass will expand when it gets hot and shrink as it cools down inside a kiln. For a fused glass project to be successful, every single piece of glass you use must expand and shrink at the same rate. If they don’t, you’ll create stress within the piece as it cools. This internal tension is a recipe for cracks and fractures, which can happen hours, days, or even weeks after you’ve taken your project out of the kiln. Sticking to one COE is the most important rule in glass fusing.
COE 90 Explained
COE90 glass is often celebrated for its stability and strength. Because it expands slightly less than its COE96 counterpart, it handles the stress of heating and cooling cycles exceptionally well. This makes it a very forgiving and reliable material to work with. Artistically, COE90 glass is known for offering a palette of rich, deep, and often more subtle colors. You’ll find an incredible variety of textures and styles within this system, making it a favorite for artists creating everything from intricate sculptural pieces to sophisticated plates and bowls. It’s a fantastic choice when you’re aiming for depth and nuance in your work.
COE 96 Explained
If you’re looking for bright, bold, and brilliant color, COE96 might be your perfect match. This glass has a slightly higher rate of expansion, a property that allows manufacturers to create some of the most vibrant and lively shades available. COE96 glass is particularly popular for projects that need to pop, like colorful suncatchers, decorative tiles, and eye-catching jewelry. It’s also a go-to for working with dichroic glass, which offers that stunning, shimmery effect. Many artists find its smooth, easy-to-cut nature very appealing, especially when they are just starting their glass fusing journey.
A Brief History of Glass Compatibility
You might be wondering why the glass world has two competing systems in the first place. The answer really comes down to history. As different glass manufacturers began producing fusible glass, they each developed their own unique formulas and recipes. Companies like Bullseye Glass perfected a formula that resulted in the COE90 standard, while others like Spectrum and Wissmach created their own lines that became the COE96 standard. Neither one is inherently better than the other; they are simply different systems that evolved independently. Because their chemical makeups are different, their expansion rates are different, making them completely incompatible for fusing together.
The most critical takeaway is that you must choose a side for each project. If you start a piece with COE90 glass, every other element you add—from the base sheet to the tiniest stringer or piece of frit—must also be COE90. The same rule applies to COE96. Think of it like building with two different types of blocks that don’t quite fit together. While you can’t mix them in a single fusing project, both systems offer a complete universe of colors and forms. You can create absolutely anything you can imagine within either COE, from complex patterns using slumping molds to beautiful, free-form artworks.
COE 90 vs 96: What’s the Real Difference?
While both COE90 and COE96 glasses are popular in glass fusing projects, they have distinct properties that may impact their performance and suitability.
How They Perform in the Kiln
COE90 glass is widely used in America, with Bullseye Glass as a notable supplier. This type of glass is recognized for its stability and sturdiness when fused. In contrast, COE96 is favored for its vibrant colors and the ease with which colors clear.
Physical Characteristics and Workability
Beyond the numbers, COE90 and COE96 glass feel and behave differently in your hands and during the cutting process. These physical traits can influence which glass you choose for a particular project. The texture, ease of cutting, and even the standard sizes the glass comes in are all practical considerations that affect your workflow in the studio. Understanding these differences will help you anticipate how the glass will respond, leading to cleaner cuts and a smoother creative process from the very start.
Glass Texture and Cutting
When you handle COE90 glass, particularly from brands like Bullseye, you might notice a slight texture. Often, one side is smooth while the other has a subtle “orange peel” pattern from the manufacturing process. For the best results, always score and cut on the smoother side. This texture can sometimes make COE90 a bit more challenging to cut than COE96 glass, which is frequently smoother on both sides. If you’re new to glass cutting, you might find COE96 more forgiving, but mastering the feel of COE90 is a rewarding skill that opens up a huge palette of colors and styles for your work.
Standard Sheet Sizes
The size of the glass sheet you start with can also play a role in your project planning. Generally, Bullseye COE90 glass sheets come in standard sizes around 89cm x 51cm. In contrast, sheets of COE96 glass, like those from Spectrum System 96, are typically larger, often measuring 122cm x 61cm. This difference can be significant depending on the scale of your art. If you’re creating a large panel or architectural piece, the bigger COE96 sheets might mean fewer seams. For smaller, more intricate designs or jewelry, the sheet size may be less of a factor, making either type a great option.
Firing Schedules and Kiln Time
This is where the science of COE becomes critical. Because they expand and contract at different rates, COE90 and COE96 glass require completely different firing schedules. You can’t mix them in a single fused piece without causing stress and, eventually, cracks. Each type has its own specific temperature and timing requirements for every stage of the firing process, from heating up to annealing and cooling down. Always refer to the manufacturer’s recommended firing guide for the specific glass you’re using. Programming your kiln accurately is the key to a successful, durable piece, so it’s a great habit to keep your glass scraps clearly labeled and separated in your studio.
When to Use Each Type of Glass
COE90 glass is often used for intricate projects that require high detail and strength, whereas COE96 is popular in creating luminous, eye-catching artworks. The trend around COE96 glass showcases its vibrant color palette, ideal for pieces where color intensity is necessary.
Which Glass Is Right for Your Project?
Here is where aesthetics meet functionality. COE90 has certain robust qualities that are essential in creating durable pieces, while COE96 offers a spectrum of colors that catch the eye—ideal for decorative items. When choosing, consider the lifecycle and aesthetic of your project.
Choosing a Glass for Beginners
When you’re just starting with glass art, you’ll hear the term “COE” thrown around a lot. COE stands for Coefficient of Expansion, which is a technical way of describing how much glass expands when heated and shrinks when it cools. This is the single most important factor for compatibility in your kiln. If you try to fuse glasses with different COE numbers, they will pull apart as they cool, creating stress that can cause cracks or breaks in your piece. The golden rule for fusing is simple: pick one COE and stick with it for your entire project.
For artists new to the craft, COE96 glass is often the best place to start. It’s typically more affordable, which is a huge advantage when you’re learning and experimenting. This allows you to practice cutting, shaping, and firing without the pressure of working with more expensive materials. COE96 also comes in a stunning variety of bright, vibrant colors, making it incredibly fun to work with and perfect for creating eye-catching pieces right from the beginning. Its forgiving nature and accessibility make it an ideal choice for building your skills and confidence.
As you gain more experience, you might find yourself drawn to the unique qualities of COE90 glass. It’s renowned for its stability and is often preferred for intricate, detailed projects that demand precision. While it’s a fantastic material, it’s best to master the basics with one system first. No matter which COE you choose, always check the manufacturer’s instructions and consider running a small test fire before starting a larger project. This simple step helps ensure your glass is compatible and that your final artwork turns out exactly as you planned.
Comparing the Costs of Fusing Glass
| Type | Average Price (per square foot) |
| COE90 | $10 – $15 |
| COE96 | $8 – $12 |
ArtGlassSupplies offers a variety of COE90 and COE96 glass products, , ensuring you have access to competitive prices and quality options for your glass projects.
How COE 90 and COE 96 Are Sold
When you shop for fusing glass, you’ll find it comes in various forms beyond just sheets, like frit (crushed glass) and stringers (thin rods). The way suppliers market these products often reflects the glass’s core qualities. For instance, COE90 glass is frequently presented as the premium choice for detailed, structural work due to its stability. Bullseye Glass is the most notable supplier, so its marketing emphasizes consistency and quality. On the other hand, COE96 glass is celebrated for its brilliant and expansive color palette. Because it’s produced by several manufacturers, you’ll find a wider variety of vibrant hues, often at a slightly lower price point, making it perfect for colorful, decorative projects.
What Glass Fusing Artists Are Using Now
The demand for COE90 remains strong among studios that favor technical precision and durability, while COE96 is gaining traction in the handmade jewelry and ornament markets. This reflects a global trend towards objects that offer not just functionality, but also an inherent aesthetic quality.
Key Brands and Naming Conventions
When you start shopping for glass, you’ll quickly notice that certain brand names are tied to specific COEs. Understanding these connections helps you know what to look for and ensures you’re buying compatible materials for your projects. Think of it like knowing your favorite brand of paint—you learn to trust its quality and know how it will perform. The same goes for glass. Let’s break down the major players and what they’re known for in the world of glass fusing.
Understanding System 96
You’ll often hear the term “System 96” used alongside COE96, and for good reason. It’s not just a single brand but a family of glass products from different manufacturers, all tested to be compatible with a COE of 96. This system was created to give artists a reliable and consistent range of options. Generally, System 96 glass is a bit softer and fuses at a slightly lower temperature than COE90 glass. This workability, combined with its broad availability and predictable results, makes it a popular choice for both beginners and experienced artists who value a wide, compatible palette of colors and forms.
Major Glass Manufacturers
While many companies produce art glass, a few key manufacturers have become industry standards for fusing. Their products are widely distributed, extensively tested, and trusted by artists around the world. Knowing who makes what can simplify your buying process and help you achieve the specific look you want for your next piece.
Bullseye Glass (COE 90)
If you’re working with COE90 glass, you’re most likely working with Bullseye Glass. As a leading American manufacturer, Bullseye has built a stellar reputation for producing high-quality, reliable glass. Artists often choose COE90 glass for its exceptional stability and sturdiness during the fusing process. This makes it ideal for complex projects that require precision and structural integrity. When you need crisp lines and dependable results in the kiln, Bullseye is the go-to brand that consistently delivers.
Spectrum and Wissmach (COE 96)
On the COE96 side, two major names stand out: Wissmach and Spectrum (which is now produced by Oceanside Glass & Tile). These manufacturers are celebrated for their stunningly bright and vibrant color palettes. If your project is all about creating visual impact with bold, saturated hues, COE96 glass is an excellent choice. Artists gravitate toward these brands when they want to create eye-catching decorative pieces, jewelry, or any artwork where color is the star of the show. The extensive range of colors available from these makers provides endless creative possibilities.
Which Glass Offers More Color Options?
Color is a transformative element in glass making. COE96 offers a diverse array of colors and patterns that can be integrated smoothly, making it attractive for mixed designs. ArtGlassSupplies provides both types, enabling artists to select according to their creative requirements.
The Expansive Palette of COE 90
When you’re working on a project that demands precision and durability, COE 90 is often the go-to choice. This type of glass is known for being incredibly stable and strong, handling temperature changes in the kiln with grace because it expands less than its COE 96 counterpart. This stability makes it a reliable material for detailed and intricate work. The color palette of COE 90 glass tends to be richer and deeper, offering a sophisticated range of hues. With a wide variety of textures and styles available, it’s particularly well-suited for kiln-forming techniques. Think of it as the perfect medium for creating detailed glass sculptures, custom jewelry that will stand the test of time, or even stunning architectural pieces.
Dichroic Glass and COE 96
If your goal is to create art that pops with brilliant color, COE 96 is your best friend. This glass is celebrated for its bright and vibrant hues that seem to glow from within. Because it expands slightly more than COE 90, it produces incredibly vivid results after firing. This quality makes it a popular choice for specialty glass, particularly dichroic glass, which has that stunning, color-shifting metallic coating. The extensive range of patterns and textures available in COE 96 glass makes it perfect for projects where you want to make a bold statement. It’s an excellent option for creating eye-catching mosaics, vibrant stained glass panels, and decorative pieces that demand attention with their luminous colors.
The Risks of Mixing Different COE Glass
The technical challenges involved in mixing glasses of different COEs should not be underestimated. While COE90 is famous for its stability, mixing it with COE96 can result in a project failure due to incompatible expansion rates, leading to breakage.
Inter-Brand Compatibility Issues
The most critical rule in glass fusing is to never mix glasses with different COE values in the same project. When you heat glass in a kiln, it expands, and when it cools, it contracts. COE90 and COE96 glasses do this at different speeds. Fusing them together means one will shrink faster or more than the other, creating immense internal stress. This incompatibility isn’t just a suggestion; it’s a fundamental principle. For example, you cannot fuse Bullseye glass, which is a popular COE90 glass, with System 96 glass. The difference in their expansion rates will cause them to pull each other apart during cooling, leading to cracks or even shattering. To ensure your artwork remains intact, always stick to one COE throughout a single piece.
Can You Fuse COE 90 and COE 96 Glass Together?
Mixing different COEs requires a cautious approach. Small deviations between COE90 and COE96 can become problematic when fused, but strategic selection of glass can sometimes work, especially when using advanced techniques.
When COE Doesn’t Matter: Stained Glass vs. Fusing
After all this talk about the critical importance of COE, you might be surprised to learn there’s a whole area of glass art where it’s much less of a concern. If your passion is stained glass, you have a lot more creative freedom. In stained glass projects, individual pieces of glass aren’t melted together in a kiln. Instead, they are joined using flexible metal channels, like lead came or copper foil, and then soldered. This construction method creates a buffer between the pieces of glass, allowing them to expand and contract at slightly different rates without causing stress or breakage.
This is the complete opposite of glass fusing, where every piece melts to become a single, solid object. In fusing, even a tiny incompatibility in COE can create immense internal stress as the piece cools, leading to cracks and project failure. Because stained glass construction is more forgiving, artists can mix glass from different manufacturers and even different COEs without worry. This opens up a wider world of colors and textures for your stained glass panels, lamps, and suncatchers, letting you focus purely on the artistic vision for your piece.
Practical Tips for Your Studio
Keeping your glass types straight is fundamental to success, especially when you work with both fusing and stained glass techniques. A little organization goes a long way in preventing costly mistakes and saving you time. Setting up good habits in your workspace ensures that you can focus on your creativity without having to second-guess your materials. These simple practices can make a huge difference in the quality and integrity of your finished work, helping you avoid the frustration of a project gone wrong due to a simple mix-up.
Keeping Your Glass Scraps Organized
Every glass artist knows that the scrap bin is a treasure trove of potential for future projects. However, a disorganized scrap pile can quickly become a liability. The most important rule for your studio is to keep your glass scraps separated by COE. Mixing up a piece of COE90 glass with your COE96 scraps can lead to a cracked piece and a lot of wasted time. Get into the habit of using clearly labeled bins for each type of glass. It’s wise to have separate containers for COE90, COE96, and any non-fusable glass you use for stained glass projects. This simple organizational step is one of the best ways to protect your work and materials.
The Importance of Test Firing
Think of test firing as insurance for your art. Before you commit hours of work and valuable materials to a large or complex fusing project, running a small test is always a good idea. By firing a small sample of the glass you plan to use, you can see exactly how it will behave in your specific kiln with your intended firing schedule. A test fire can reveal how different colors react with each other, confirm compatibility, and help you fine-tune your process. This small, upfront investment of time can save you from the disappointment of discovering an issue after your main project is already in the kiln. It’s a professional practice that gives you predictability and peace of mind.
Trusting Your Creative Vision
Artistry in glass is as much about the choice of material as the imagination behind it. Whether opting for COE90 with its steadiness or COE96 with its vibrancy, each selection sets a different tone for the creative expression.
Key Takeaways
Choosing between COE90 and COE96 comes down to the kind of project and the desired effect. While COE90 is ideal for strength and detail, COE96 is favored for eye-catching aesthetics. By understanding the properties, costs, and applications, artists can make an informed decision and select the best material suited to their artistic vision.
FAQs
How can I tell COE 90 and COE 96 glass apart?
Identifying COE90 and COE96 glass types can often be done by consulting the manufacturer’s labeling on the product. Both types are visibly similar, yet vary slightly in texture and thickness. It’s crucial to follow manufacturer labels for accuracy. When purchasing from reputable suppliers like https://www.artglasssupplies.com/, you’re assured of accurate COE ratings consistent with industry standards.
What are the best projects for COE 90 and COE 96 glass?
COE90 glass is typically used in projects that require precision and detail, like detailed imprints and strong fused constructions. COE96 is ideal for its aesthetic applications, especially in decorative pieces where vibrant colors are integral. These are common in jewelry and decorative panels. Each type offers distinct advantages based on desired application outcomes.
Is it safe to mix COE 90 and COE 96 glass?
Mixing COE90 and COE96 glass can be risky due to varying thermal expansion rates. However, experienced artists sometimes apply advanced techniques to merge them successfully. If unsure, starting with matching COEs is advisable until a firm understanding of the material’s behavior on cooling is obtained.
Where can I buy COE 90 and COE 96 glass?
Reliable suppliers such as https://www.artglasssupplies.com/ offer a range of COE90 and COE96 glass, ensuring availability and quality. They offer structured browsing, allowing customers to view and compare products suited to specific project requirements, fostering optimal creation results.
Why does the COE of glass matter so much?
The Coefficient of Expansion is significant because it influences compatibility between glass pieces. Choosing a matching COE ensures that fused glass pieces expand and contract uniformly during heating and cooling in the kiln. Incorrectly matched glasses can lead to tensions and eventual breakage, impacting project durability and aesthetics. ArtGlassSupplies strives to support artists with quality materials, , ensuring their glass projects reach the creative and technical standards of expert artistry.