Clear float glass contains more iron, giving it a green tint and slightly lower light transmission. Low-iron glass has reduced iron content, offering higher clarity, better color neutrality, and greater visible light transmission — but at a higher cost.
These two types of glass may look similar at first, but their differences show up fast—especially in how they handle light, color, and cost. In this guide, we’ll break down what sets them apart and when it’s worth choosing one over the other.
What’s the Real Difference Between Clear Float Glass and Low-Iron Glass?
At first glance, glass is just glass—clear, smooth, and transparent. But if you’ve ever noticed that some panels look slightly greenish while others appear perfectly colorless, you’ve seen the difference that iron can make. That green tint isn’t a trick of the light—it’s baked into the glass itself, caused by the natural iron content found in most raw materials.
Clear float glass, the most common type used in windows and doors, contains more iron. Low-iron glass, on the other hand, has that impurity reduced to a fraction. This single change shifts everything from color appearance to how much light passes through. It’s a small detail with surprisingly large consequences—and understanding it will help you make better decisions, whether you’re designing a home, fitting out a gallery, or specifying materials for commercial use.
So let’s break down exactly what these two types of glass are, how they differ, and why one might suit your project better than the other.
What Is Clear Float Glass and Why Is It the Standard Option?
For decades, clear float glass has been the foundation of modern glazing. It’s made using the float process, where molten glass is floated on a bed of molten tin, resulting in a smooth, flat sheet with even thickness. It’s the glass you see in everyday windows, tabletops, picture frames, and interior partitions.
But the name “clear” is a bit generous. Standard float glass contains about 0.1% iron oxide, and that tiny amount gives the material a faint green tint. In thin pieces, it’s barely noticeable. But as the glass gets thicker—or if you stack sheets together—the color becomes more obvious, especially when viewed from the edge.
Still, this glass has earned its place. It’s widely available, cost-effective, and versatile. You can cut it, temper it, laminate it, or coat it for energy performance. In most general-purpose applications, it gets the job done without fuss.
That said, the greenish cast can be a drawback when color fidelity, light transmission, or visual neutrality really matter. And that’s where low-iron glass comes in.
What Is Low-Iron Glass and What Sets Low-Iron Glass Apart?
Low-iron glass starts with the same idea—but it’s made from purer materials. The silica sand used in its production has far less iron content, often just 0.01%. That single change removes the green tint almost entirely and gives you a result that’s often called “water-white” or “extra-clear.”
It’s hard to unsee once you’ve compared them side by side. Low-iron glass appears bright, neutral, and true to color—even in thick cuts. Its edges are pale or slightly blue instead of green, and it transmits more visible light, typically around 91–92% compared to 83–85% for regular glass.
This clarity isn’t just a visual bonus. It has real-world effects: displays look sharper, rooms feel brighter, and architectural lines seem cleaner. That’s why low-iron glass is often used in showrooms, museums, retail storefronts, and luxury bathrooms. It’s the kind of glass that gets out of the way and lets everything behind it take center stage.
Now that we’ve defined the two types, let’s look at how they compare side-by-side—because the differences go beyond appearance alone.
Clear Float vs. Low-Iron Glass: Key Differences in Clarity, Color, and Cost
| Feature | Clear Float Glass | Low-Iron Glass |
| Clarity | Slight haze in thick panels | Ultra-clear, crisp view |
| Color | Greenish tint, visible on edges | Neutral, colorless appearance |
| Light Transmission | ~83–85% | ~91–92% |
| Color Accuracy | Slight distortion | True-to-color rendering |
| Cost | Lower | 20–40% higher |
| Strength | Same as low-iron | Same as clear float |
| Thermal Effect | Slightly blocks more solar heat | Transmits more solar energy |
| Eco Impact | Easier to recycle, more cullet | Lower cullet use, higher energy |
Although both clear float and low-iron glass start from the same basic materials and follow the same manufacturing process, the differences between them go well beyond surface level. They diverge in how they handle light, how they appear in real-world use, how they interact with heat and color—and even how they’re priced and recycled. Let’s walk through each difference so you understand not just what separates them, but why those differences matter in practice.
Clarity
Clarity is the most visible difference—and arguably the most important. Standard clear float glass, despite the name, isn’t perfectly clear. It contains natural iron impurities that absorb and scatter parts of the visible spectrum, especially in the blue and violet range. That results in a slightly hazy or muted effect, particularly noticeable in thick glass.
Low-iron glass, on the other hand, is engineered to reduce those impurities. By using ultra-pure raw materials, it removes most of the iron that causes visual distortion. The result is what many in the industry call “water-white” glass: optically neutral, sharp, and free of any noticeable tint. If you’re placing two pieces side by side, the difference is immediately obvious—especially when viewed through the edge.
So when you need the clearest possible view—whether for a luxury interior, an art gallery, or a high-end display—low-iron glass gives you that open, unobstructed look that standard float glass simply can’t match.
Color Appearance
Alongside clarity comes color. The green tint of clear float glass is subtle in small panes but becomes more pronounced as thickness increases. The edge of a 12 mm or 19 mm clear glass sheet, for example, can look distinctly green—even dark green at times. This coloration also bleeds into the view through the surface, subtly muting colors and adding a cool tone to everything seen through the glass.
Low-iron glass avoids this by minimizing the iron content that causes the green hue. It remains almost completely neutral, with only a faint bluish or aqua tint at the edges, even in very thick pieces. What you see through it is what’s actually there: whites appear white, reds remain vivid, and the overall tone is natural and true. That’s why it’s often used in applications where accurate color rendering is critical, from retail showcases to art framing.
Light Transmission
The difference in iron content doesn’t just change color—it directly affects how much light passes through. Standard clear float glass typically transmits about 83–85% of visible light at a 6 mm thickness. The remaining percentage is absorbed or reflected, mostly because of the iron.
Low-iron glass, with far less of that absorbing material, can let through 91–92% of visible light at the same thickness. That may not sound dramatic, but over a large installation—like a full wall of windows or an exhibition enclosure—it makes a space noticeably brighter and clearer.
This improved light transmission isn’t just about appearance. In some commercial and industrial applications, every percent of daylight counts—whether it’s reducing artificial lighting costs in a building or maximizing solar energy yield in a photovoltaic panel. That’s why low-iron glass is the standard choice in solar applications and daylight-optimized architecture.
Cost
Here’s where the trade-off comes in. All that extra clarity and performance doesn’t come cheap. Low-iron glass typically costs between 20% and 40% more than standard clear float glass, depending on the region, thickness, and supplier. In some cases—especially for larger or more custom sizes—the price difference can be even higher.
That price premium reflects not only the purer raw materials used in low-iron glass, but also the more controlled manufacturing process needed to maintain its quality. And since demand is lower compared to clear float, it’s not always produced at the same scale, which means fewer cost savings from volume.
For some buyers, that higher cost is well worth the benefits. For others, especially in projects where appearance isn’t critical, standard float glass offers better value. It really comes down to what the glass needs to do: if it just needs to be strong and transparent, float glass works. If it needs to elevate how something looks or feels, low-iron glass justifies the expense.
Strength and Processing
Surprisingly, the mechanical strength of both glass types is virtually identical. Both clear float and low-iron glass are soda-lime silicate glass, and when annealed, they share the same baseline physical properties: hardness, tensile strength, modulus of elasticity, and so on.
Both can be tempered, laminated, drilled, and coated using the same fabrication techniques. Once tempered, they become 4 to 5 times stronger than their annealed state, regardless of iron content. And in safety applications—like shower enclosures, railings, or storefront doors—either type performs equally well when properly processed.
The only small caveat is that the higher optical clarity of low-iron glass can make surface defects like scratches or smudges more noticeable. That doesn’t mean it’s more fragile—just that imperfections show up more clearly. In high-end projects, extra care is usually taken in handling and cleaning to preserve that pristine look.
Thermal Performance
From a thermal standpoint, both types of glass behave similarly in terms of conductivity and expansion. But there is a difference in how they interact with solar energy.
Clear float glass, because of its higher iron content, absorbs slightly more infrared radiation. That means it has a marginally lower solar heat gain coefficient (SHGC), which could help reduce heat buildup in hot climates—though the effect is minor. Low-iron glass, with less absorption, allows more solar energy through. This can be a benefit in passive solar design or cold-climate buildings, where capturing more warmth from sunlight is desirable.
In practical terms, most modern window systems include low-emissivity (low-E) coatings or tints that play a much larger role in managing heat gain or loss. Whether the glass beneath those coatings is low-iron or standard float becomes less important once those layers are applied. But in uncoated applications—like greenhouses, solar panels, or display enclosures—low-iron’s higher solar transmission can offer measurable advantages.
Environmental Impact
Finally, there’s the question of sustainability. Glass manufacturing is an energy-intensive process, and neither type is inherently “green.” Both require melting raw materials at high temperatures and generate CO₂ emissions in the process.
However, clear float glass has a slight edge in terms of recycled content. Because its color tolerance is broader, manufacturers can use more post-consumer recycled glass (called cullet) in the batch without worrying about iron levels. This helps reduce raw material use and energy consumption.
Low-iron glass, by contrast, requires cleaner inputs. Only cullet from other low-iron batches can be used, and that limits the available supply. As a result, some low-iron glass may have lower recycled content and slightly higher embodied carbon per square meter of product.
On the flip side, once installed, low-iron glass may contribute to energy efficiency—either by improving daylight harvesting or by boosting the effectiveness of solar installations. So the net environmental impact depends not just on how the glass is made, but how it’s used.
When to Use Clear Float Glass
In most buildings, clear float glass is still the default. Its combination of affordability, strength, and flexibility makes it ideal for basic windows, interior doors, mirrors, and standard glazing. When you’re not worried about perfect color rendering—or when the glass is thin enough that the green tint is minor—clear float is the practical choice.
It’s especially common in framed applications, like picture glass or double-pane windows, where edge tint and color distortion aren’t visible. Its global availability also makes it easier to source for projects on a tight schedule or budget.
So if you’re working on a cost-sensitive development or outfitting a commercial space where the glass isn’t meant to draw attention, standard float glass is probably the right move.
But in projects where the glass itself plays a starring role—or where what’s behind the glass matters more—low-iron begins to justify its higher price.
When to Choose Low-Iron Glass
Low-iron glass isn’t about being flashy—it’s about being invisible. That’s its power. When clarity is critical—whether you’re framing artwork, presenting merchandise, or designing a luxury shower—low-iron glass helps eliminate distractions. It ensures that colors come through true, light isn’t lost unnecessarily, and edges don’t glow green.
In museums and galleries, the goal is to showcase what’s inside, not the glass itself. In retail displays, particularly for jewelry, electronics, or cosmetics, low-iron glass makes products look more vibrant and appealing. Architects use it for stair rails, curtain walls, and frameless partitions when they want a clean, open feel.
And beyond looks, low-iron glass has performance value too. In solar panels and greenhouse glazing, more light transmission means more energy collected or more growth encouraged. It’s a small gain that can add up over time.
In short: when appearance is part of the performance, low-iron is the way to go.
Conclusion: Making the Right Choice
There’s no wrong answer—just different priorities. Clear float glass offers reliability and value. It’s everywhere for a reason: it’s good enough for most uses, and the green tint is only an issue in specific situations.
Low-iron glass, on the other hand, is about going that extra step. It removes the one visible flaw from standard glass and lets the light—and everything behind the glass—shine through as clearly as possible.
So here’s the rule of thumb: when clarity matters, choose low-iron. When it doesn’t, stick with the standard float.
Because in the end, choosing the right glass isn’t just about the glass itself—it’s about what you want people to see when they look through it.
FAQs: Low-Iron vs. Clear Glass
What is low-iron glass also called?
Low-iron glass is often referred to as ultra-clear, extra-clear, or water-white glass. Manufacturers have their own brand names too—like Starphire, Optiwhite, Diamant, and UltraClear.
Is low-iron glass stronger or more durable than standard glass?
No, the strength is essentially the same. The difference is in appearance, not structural performance. Both can be tempered, laminated, or coated.
How much more does low-iron glass cost?
On average, you can expect to pay 20% to 40% more for low-iron glass. The premium reflects the higher-purity materials and the controlled production process.
Can I use coatings on low-iron glass?
Absolutely. Low-iron glass is often used as the base for high-performance glazing, including low-E, anti-reflective, and solar-control coatings. In fact, because it’s more neutral, coatings on low-iron glass tend to look cleaner and more consistent.
Will I always need low-iron glass for thick panels?
Not necessarily. But the thicker the glass, the more obvious the green tint becomes in standard float. For thick balustrades, tabletops, or laminates, low-iron is often chosen to avoid a heavy green edge.
