For decades, glass and metal have been the salt-and-pepper, ketchup and mustard, peanut butter and jelly of architectural design. They just go together and always have. Yet, when it comes to making glass and metal look better together, the solution—ironically—is to use glass with a lot less iron in the formulation.
Following is a brief primer on low-iron glass, what it is, what it does, how to specify it, and why it can be essential to highlighting the beauty of metal building components and applications.
What is Low-Iron Glass?
Glass is made from sand, lime and soda ash and even when it is clear or untinted, there is always a hint of green in the color due to the presence of iron impurities in the sand. About 30 years ago, several glass manufacturers, including PPG (now Vitro Architectural Glass, Cheswick, Pa.) and LFO (now Pilkington, Toledo, Ohio), introduced glass products that were formulated with low iron content with the goal of eliminating the subtle green tint in regular clear glass and creating brighter, more transparent, ultra-clear glass for buildings, display cases, shower doors, interior partitions and other applications.
Today, low-iron glass is being selected for more architectural applications than ever, a trend driven by two factors. The first is increased demand from architects and building designers for clearer glass. The second is the proliferation of low-iron glass options now available from manufacturers in the U.S., Europe and China.
Are There Different Types of Low-Iron Glass?
Low-iron glass products vary by manufacturer. Companies that make low-iron glass have proprietary formulations that vary from one another in multiple ways, but the most significant distinction among them is typically the type and quality of sand each one uses. When an architect, designer or specifier compares low-iron glass products from different manufacturers, there are usually noticeable differences in clarity. Relatively speaking, some low-iron glasses look bluer, while others may look more yellow or green, though all are definitively clearer than regular clear glass.
“Today, low-iron glass is being selected for more architectural applications than ever, a trend driven by two factors. The first is increased demand from architects and building designers for clearer glass. The second is the proliferation of low-iron glass options now available from manufacturers in the U.S., Europe and China.”
How Can I Identify the Right Low-Iron Glass for my Component or Application?
Here are four tips to choosing the right low-iron glass for your project:
- Always ask for glass samples: All low-iron glass manufacturers provide 4-inch by 6-inch or 12-inch by 12-inch glass samples for architects and designers to review during the design/specification process. This enables them to make an initial visual comparison among the competing products they are considering. The best way to compare low-iron samples is to line them up in front of a white sheet of paper or wall and view them under the most natural lighting conditions available.
- Always request mock-ups: Once you’ve settled on one or two (or more) potential options, the next step is to order full-size mock-ups of the glass inside a full metal framing system replicating its finished application on the building. Mock-ups should always be viewed in natural daylight, ideally at the job site or in similar building surroundings. This helps account for three-dimensionality and all the variables you can’t see when viewing basic glass samples in an office setting, such as landscaping, or shadows cast by nearby buildings.
- Always involve the glass manufacturer in the design/specification process: Use the experience glass manufacturers have in working with architects and designers to make the absolute best choice for your application.
- Don’t mix and match: When low-iron glass is be used in an insulating glass unit or finished with a laminate, be sure that every lite in the configuration is a low-iron glass (not clear glass) to maximize the effect.
Why Should I Use Ultra-Clear Glass Instead of Clear Glass?
Due to its cost, low-iron glass often is value-engineered out of projects to save money. There are many applications, however, where its extra clarity is worth the slight premium. For instance, low-iron glass is ideal for storefront applications, such as retail stores, car dealerships and restaurants, where branding and logo fidelity are critical.
Low-iron glass should also be considered for applications where color rendering or color harmonization with metal, paint and other building materials are priorities. It also is the best choice for heavy glass applications, such as entry door systems, as the thickness of regular clear glass can intensify its subtle green appearance and give it a tinted look.
Other common exterior architectural applications for low-iron glass include curtainwalls, façades, spiderwalls and skylights, as each can benefit from the brilliant clarity that these specially formulated products provide.
Where Can I Learn More?
The best place to learn about the full range of low-iron glass products now available is to visit glass manufacturer websites. The best way to compare them is to order samples and mock-ups and to view them side-by-side according to the instruction provided above.
Emily Losego is an architectural services team leader and Nathan McKenna is market manager for Vitro Architectural Glass, Cheswick, Pa. Each works every day to help customers evaluate and specify the best glass products for their applications. For more information, visit www.vitroglazings.com.
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