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The Difference Between Clear & Low-Iron Glass

The difference between clear and low-iron glass is the greater transparency of the latter, making it more suitable for certain uses such as frameless glass walls, back-painted glass, markerboards, UV-bonded display cases, shelving, partitions and dividers, and other appearance-driven applications.
Published July 28, 2022

Glass wall office with brick wall in background and text - The Difference Between Clear & Low-Iron Glass

Editor’s Note: This blog post was originally published in December 2016 and has been revised to reflect industry updates.

You might think 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 glass types. 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 uses. 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 project.

Below we’ll discuss the differences between clear and low-iron glass, and the best uses and applications for each. 

 

Compare clear and low iron glassThe visual difference between clear glass (left) and low-iron glass (right).

Clear Glass

It’s a common misconception that 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 levels produce a greenish tint, gaining 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 melted. This can cause issues within certain applications and uses. 

If your project calls for custom back-painted glass, your fabricator will typically recommend low-iron glass. With a clearer canvas, back-painting is much smoother, making the finished product the exact shade required for your project. Therefore, architects and designers prefer fabricators to use low-iron glass when color-matching.

When displaying elegant wares, such as jewelry and other high-end items, these fine details and subtleties may not be as apparent to even the slightest touch of green present in a clear glass case.

Low-Iron Glass

While clear glass is appropriate for projects not requiring high-level displays or added decorative elements, low-iron glass is likely the better choice for markerboards, frameless glass walls, UV-bonded display cases, shelving, 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 is more transparent than regular glass, and doesn't have that aforementioned greenish tint. In fact, modifying iron content can increase the light transparency by 5 percent to 6 percent.

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 higher transparency and opacity levels, 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.

When compared to clear glass, low-iron glass emits additional light to increase seamless continuity between spaces. 

Choosing the Right Low-Iron Glass
for Your Application

Because the composition of low-iron glass can vary through specific formulas and processes, there is still a slight tinge of iron. When deciding on the right type of low-iron glass for your application, consider the following recommendations:

  • Request Samples & Mockups From Your Glass Fabricator: This facilitates actual iron levels while demonstrating opacity and transparency of glass lites. 
  • Outline Specifications: This is especially important if the application is designated for high-end or display-driven environments.
  • Ensure All Parties Are Onboard: Conduct open communication with your glass fabricator on any changes and specifications.
  • Don’t Mix & Match Materials: For utmost clarity, it’s best to avoid combining low-iron glass with clear glass. 

While clear glass is appropriate 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. 

 

Can I Use Glass That Doesn’t Contain Any Iron?

Some level of iron is required when producing glass, and hence a necessary ingredient for a stronger, durable, and long-lasting solution. Because low-iron glass is created without specifications outlined by standards organization ASTM International, clarity and iron levels will vary. It’s therefore recommended to discuss this process with a reputable glass fabricator.

 

Determining the Differences

Whether your needs require clear glass or low-iron glass, it’s best to work with a fabricator who understands your project designs and goals. They can ensure completion is on time, on budget, and with the highest standards.



Contact us to determine if your project and application is best suited for clear or low-iron glass.

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