Editor’s Note: This blog post was originally published in December 2016 and has been revised to reflect industry updates.
You might think that all glass is made the same. Yes, glass is available in different shades and shapes, but its actual composition cannot be altered, right?
This couldn’t be further from the truth.
Different products require different types of glass. Two common categories are low-iron and clear. Their properties differ because their ingredients aren't the same, so one may be better suited than the other for certain projects.
An experienced fabricator, such as Dillmeier Glass Company, can explain the distinction between low-iron and clear glass and also recommend which is best for your application.
Below we’ll discuss the differences between clear and low-iron glass, and the best uses and applications for each.
The visual difference between clear glass (left) and low-iron glass (right).
You might think clear glass is the most transparent, however, this actually is not the case. Although clear glass does not have substantially high iron content, it does have more than low-iron glass.
These higher iron levels produce a greenish tint appearance, which gains prominence as the glass thickens. This is a result of the natural presence of iron oxide from elements such as sand, or from the cask or container whereby the glass was actually melted. Despite being a logical process, this can cause issues within certain applications.
If your project calls for back-painted or color-matched glass your fabricator won't want to use regular, clear glass because it will be harder to match the color. Glass fabricators will typically recommend low-iron glass instead.
Another application is displaying elegant wares, such as jewelry and other high-end items. These fine details and subtleties may not be as apparent due to even the slightest touch of green present in a clear glass case.
While clear glass is suitable for projects not requiring high-level displays or added decorative elements, low-iron glass is likely the better choice for markerboards, frameless glass walls and glass dividers.
Float glass manufacturers create low-iron glass, also known as extra-clear glass or optically clear glass, by reducing the amount of iron in the molten glass formula. This type is more transparent than regular glass, and doesn't have that greenish tint. In fact, modifying the iron content can increase the light transparency by 5 to 6 percent.
Low-iron glass also increases the flow of natural light, for added, seamless continuity between spaces.
With a clearer canvas, back-painting is much smoother, making the finished product the exact shade for your project. Therefore, architects and designers prefer glass fabricators to use low-iron glass when color-matching.
Since the edgework of low-iron glass is less green than clear glass, it's not just suited for color matching—it is also appropriate for retail display cases and shelves—leading to opportunities for potential conversion through compelling product displays.
According to research by conversion consulting firm Invesp: “8 eight out of 10 impulse buys are made in a brick-and-mortar store.”
Because of this high transparency, consumers can view merchandise without the interference of green tint. This could also be useful within hotel lobbies, office waiting rooms, or other areas utilizing glass display cases.
“Due to its composition, low-iron glass can transmit up to 91 percent of light compared to the 83 percent associated with conventional clear glass, allowing it to be used in a variety of different applications.”
Can I use glass that doesn’t contain any iron?
Because some level of iron is required when producing glass, it’s therefore still a necessary ingredient for a stronger, durable, and long-lasting solution.
Since low-iron glass is created without specifications outlined by standards organization ASTM International, clarity and iron levels will be varied. If you’re unsure of specifications for your project, it’s recommended to work with an experienced fabricator, such as Dillmeier Glass Company, for best practices.
Determining the Differences
Whether your needs require clear or low-iron glass, it’s best to work with a fabricator who understands your project designs and goals. They can draw upon their experience to ensure everything is completed on time, on budget, and at the highest standards.
Contact us to determine if your project and application is best suited for clear glass or low-iron glass.