September 22, 2017

Why should I specify Low Iron Glass?

Written by Rebecca Clayton

Luxury Hertfordshire home with minimal glazing
Water End House, Hertfordshire, 2017. Architect: Kirkland Fraser Moor.

The beauty of a glass structure is that they are clear and transparent. Large elevations of glass, especially frameless structural glass, provide unparalleled levels of light ingress into a space as well as fantastic viewing portals out over views.

But did you know that ‘clear glass’ is not in fact totally clear? Natural ‘clear’ glass is full of additional materials and impurities. These additional materials mixed into the molten glass pane creates a glass panel that has a slight colouration to it. You can see this most noticeably on thicker panes of glass and structural glass installations where higher specification glass panes are needed.

In these ‘clear glass’ panels you can see a noticeable green tinge to the glass installation. This is due to a very common impurity within normal glass; iron oxide.

This is where low iron glass can be a fantastic solution for architectural projects, especially where thick structural glass installations are going to be specified.

Low iron glass is manufactured with a lower iron oxide content within the molten glass. This is done by adding additional filtering and purification processes into the manufacture of this specialist glass. The result is a glass panel with a reduced iron oxide content and a clearer resulting appearance.

The specialist glass panes can then be toughened, laminated and finished to your normal project specification as if they were standard clear glass units and integrated into your structural glass designs. There is no change in the strength of low iron glass when compared to standard glass which makes these units perfect for structural glass assemblies where the glass strength is paramount.

Using low iron glass for glass beams and fins

A structural glass beam or fin is most often the thickest example of structural glass that is found on a project. These frameless glass supporting members are often used to support a structural glass roof, glass box extensions and large frameless glass facades.

To make a glass element that is able to withstand the required loading, be that wind loading for facades or support for a structural glass roof, you need to use many layers of toughened glass laminated together. If you were to use normal clear glass to create a glass beam or fin the resulting glass supporting design would have a very strong green tint.

When you make a glass beam or fin from low-iron glass instead the structure is clear, just like you would want if you were using a material like glass to support a structure.

Glass Fins

Using Low Iron Glass For Glass Floors

The glass specification for a structural glass floor will differ from project to project depending on the size of the floor and the expected traffic over the glass structure. You would often be looking at a glass unit that has at least three pieces of toughened glass laminated together for the top layer and that is before you consider double or triple glazing for insulation.

The clearer finish of low iron glass can be utilised very well here to create a walk on glass element with maximum transparency.

This clarity can be even more important when you choose a sandblasted surface for a glass floor. When you remove the transparent nature of glazing by sandblasting then the colouration of the glass itself becomes more noticeable, low-iron glass will result in a sandblasted glass surface with a white frosted surface rather than a green frosted surface.

Glass Floor

Using Low Iron Glass For Glass Walls

As a structural glass wall has no frame the glass itself has to be designed to withstand all wind and line loading for the elevation. A structural glass wall will therefore use a thicker glass specification than your standard framed facade or curtain walling system. This increase in glass thickness will produce a glass unit that has a stronger green tint and therefore low iron glass is often used to get as much clarity to these facades as possible.

Low iron glass can be especially useful for a facade design when you are mixing framed windows or doors into the frameless glass facade. The glass within the framed system will be a different thickness to the glass used for the frameless glass facade which could result in a different tone to the different glazed elements. Using low iron glass in these instances will remove the tonal changes from different thicknesses of glass elements and make the entire glass facade clear.

structural glass walls Water End House, Hertfordshire, 2017. Architect: Kirkland Fraser Moor.

Using Low Iron Glass For Glass Balustrades

A glass balustrade will be made from at least two layers of toughened glass laminated together. When compared to other structural glass elements the resulting glass thickness isn't that large. However, the one difference between a structural glass balustrade and a glass wall is that you see the edges of a glass balustrade.

It is around the edges of a structural glass balustrade that the green tint from clear glass can be very visible. Using low iron glass for a glass balustrade will reduce the tint you will notice around the edges of the balustrade and the clearer and more invisible the overall installation becomes.

Glass Balustrades

Changing a glass specification from clear glass to low iron glass will add roughly £60 per metre square of glass. This cost comes from the additional processes that are needed during the manufacturing process.

If you want to include low iron glass on a project make sure that this is included in the initial cost to save nasty surprises later. When IQ price a glass beam for example we would always price for low iron glass as standard but other glazing companies may not do so.

Do you want to see a low iron glass beam in person? We use low iron glass beams and fins as the support for the structural glass box extension at our showroom. If you would like to make an appointment to visit The Courtyard Showroom @ Sky House, or if you have any questions about using low iron glass on your project, just give us a call on 01494 722 880 or email

IQ Glass Showroom