Low iron is a term used in glass. It means the glass is made with a low iron content. Iron is present in the raw materials of standard clear float glass and gives it a green tinge, most visible on the edges and in thick or laminated glass. Low-iron glass removes most of that tint, making the glass clearer and truer in colour. It is often specified by architects and interior designers.
How low-iron glass is made
It is made by the same float process as standard glass, but with raw materials, mainly sand, selected for very low iron oxide. It can then be tempered, heat-strengthened, laminated, coated, back-painted or used in insulating glass units like any other float glass.
Low iron vs clear glass
| Standard clear glass | Low-iron glass | |
|---|---|---|
| Edge colour | Noticeably green | Pale blue or nearly neutral |
| Clarity and colour | Slight green cast, stronger with thickness | Very clear, true colour rendering |
| Light transmission | Good | Higher; the difference grows with thickness |
| Cost | Base price | Premium |
Common trade names include Starphire (Vitro), Optiwhite (Pilkington) and UltraClear (Guardian).
Where it is used
- Storefronts, entrances and high-end curtain wall vision glass
- Glass balustrades, railings, floors and stair treads
- Shower enclosures, mirrors and display cases
- Back-painted glass and coloured spandrel panels, where true colour matters
- Solar panels and aquariums
Low iron vs low-E glass
They are different things. Low iron describes the glass itself and affects clarity and colour. Low-E (low emissivity) is a thin metallic coating applied to glass to improve thermal performance. A unit can use low-iron glass with a low-E coating.
Specifying tips
- Use low-iron glass consistently across an elevation. Standard and low-iron lites side by side show a visible colour difference.
- For laminated glass, state that every ply is low iron.
- Check availability, lead time and price for the thickness and size you need, and approve a sample or mockup.
Related terms
Related templates and guides
- Curtainwall – Quality Control Checklist
- Interface Guidelines For Curtainwall
- Basics of Building Envelope Construction
Frequently asked questions
Does low-iron glass really make a difference?
Yes, where clarity or colour matter. The difference is small in a single thin pane but obvious on exposed edges, thick glass, laminated glass, glass railings and anything back-painted or white. In standard windows seen from a distance, many people cannot tell.
How can you tell if glass is low iron?
Look at the edge. Standard float glass shows a distinct green edge, while low-iron glass looks pale blue or almost clear. Laying the pane on a white sheet of paper also shows the green tint of standard glass.
Is low-iron glass more expensive?
Yes, it carries a premium over standard clear glass, which varies with thickness, size, processing and supplier. Get pricing early, especially for thick laminated or large lites where availability and lead time can also be an issue.
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