Scratches on glass: repair or replace

Scratches on glass in a window can often be repaired by a glass repair specialist, and replacing the pane is not always the cheaper answer. The Glass and Glazing Federation (GGF) says that in most cases surface damage to glass can be repaired, which makes repair a real alternative to replacement in some situations. Light scratches are one case where it usually works, and deep damage is where it usually does not.

This page draws on the GGF’s advice, Repairing surface damage to glass windows, doors and conservatories.

What causes scratches on glass

The GGF lists four common causes of surface damage:

• Scratches made by hard or sharp objects, by accident or on purpose, which may fail if left untreated.
• Graffiti, etched into the glass or applied in paint or ink.
• Airborne contamination, such as bird droppings or road film, which can abrade the surface and lower its visual quality.
• Building contamination, such as run-off or sealant that has leaked on to the glass.

Scratches on the outer face of a window are the ones a specialist can reach. Scratches on new windows often appear during fitting or cleaning, which is one reason to inspect the glass at handover.

How a repair works

The GGF describes repair as removing a minimal amount of the glass surface to take out the defect, without harming its visual quality. It is a specialist job. Two limits are worth knowing:

• The damage can be too severe for repair to be practical. The specialist should tell you at the first survey.
• In exceptional cases an unacceptable level of distortion only shows during or after treatment, and then the GGF says replacement would be advised.

So a repair carries a small risk that you end up replacing the pane anyway. Ask the specialist what happens if that occurs, and who pays for the visit.

When to repair and when to replace

In many cases replacing the damaged glass is the most economical option, particularly for a small pane in a standard window. The GGF notes that repair makes more sense where replacement would be far more expensive, and gives a large landing window as an example. If you are unsure, ask a glass repair specialist to survey the damage and quote, then compare that quote with the cost of a new unit. The GGF also points out that the environmental impact of repair is much lower than replacement.

Why not polish it yourself

The GGF warns that graffiti removed incorrectly can damage the glass surface, and the same caution applies to anything that rubs the glass. Polishing compounds, abrasive pads and blades can leave marks that are worse than the original scratch, and they can wear away a coating, such as the one on self cleaning glass. If a scratch bothers you, get it looked at before you try to remove it.

Scratches on new windows

Check each pane at handover, in daylight, from inside and outside, before you sign the job off. Mention any scratch then, in writing, while the fitter is still on site. After that it is much harder to show who caused it. The guide to replacement windows for a 3-bed semi lists what a good quote includes, and the quote checker will help you compare. When you are ready, get free quotes.