Flagship guide · 11 min read
The Complete Guide to Glass Specification
The frame gets most of the attention, but the glass does most of the work. This is our full guide to choosing it properly.
Low-Iron Glass: When True Clarity Matters
Standard glass carries a faint green tint. Low-iron glass removes it, for a genuinely clear view.
3 min read
Ordinary float glass contains trace amounts of iron oxide, which gives it a subtle green tint, most visible when looking through the edge of a thick pane, comparing glass to an open doorway, or viewing a large expanse of glazing such as a sliding door. Low-iron glass uses a purer raw material with a much lower iron content, producing a noticeably clearer, more neutral pane.
It is a purely visual upgrade with no effect on thermal or acoustic performance, which makes the decision to specify it a simple one: is the clarity worth the cost for this particular opening?
Where the green tint actually shows
On a small window the green tint of standard glass is barely noticeable. It becomes more apparent as glass area and pane thickness increase, and especially where glass is viewed edge-on or compared directly to an unglazed opening — a large sliding door reveal, a glass balustrade, or a run of frameless glazing where several panes sit close together.
- Large sliding or bifold doors framing a garden or view
- Glass balustrades and internal glass screens
- Picture windows where the glass itself is the main feature
- Any glazing next to natural stone, timber or other true-colour materials where a green cast would be noticeable by comparison
Weighing up the cost
Because low-iron glass changes appearance only, the decision comes down to how much the clarity matters for a particular opening, weighed against the cost premium. It is most often chosen for the largest, most prominent piece of glazing in a project — a Lake District view framed by a sliding door, for instance — rather than specified throughout an entire house, where the cost would add up without a proportionate visual benefit on smaller windows.
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