Toughened Glass

Badge Marking

In order to comply with the relevant BS or EN standard the glass will be badge marked in the corner.

Please state at the time of ordering if you require the badge mark to be the full size mark or a line mark on the face close to the edge.  Line marks will not be visible once glazed and may be rejected by Building Control, FENSA, or similar bodies.

It is not possible to always align the badge marks in an insulating glass unit; the glass may bow during the toughening process and they will be paired as best they can for sealing of the insulating glass unit.



1.  The glass shall be viewed from the room side standing at a distance of not less than 3 metres in natural daylight and not in direct sunlight.  The area to be viewed is the normal vision area with the exception of a 50mm wide band around the perimeter of the unit.

2.  The glass shall be deemed acceptable if the following phenomena are neither obtrusive nor bunched: totally enclosed seeds, bubbles or blisters; hairlines or blobs; fine scratches not more than 25mm long; minute embedded particles.  Obtrusiveness of blemishes shall be judged by looking through the glass, not at it, under lighting conditions as described in 1.

3.  When toughened glass is viewed by reflection, the effect of the toughening process may be seen under certain lighting conditions.  The visibility of surface colouration or patterns does not indicate deterioration in the physical performance of the toughened glass.  Because of the nature of the toughening process, distortion can be introduced.  Such distortion will be accentuated when glass is viewed in reflection or incorporated in insulating glass units.


The nature of the toughening process, heating the glass to approximately 700 degrees centigrade and cooling rapidly whilst the heated glass is rolled over a series of rollers, induces bow into the glass.  This is an inevitable part of the process and is unpredictable, being dependent on a combination of factors and the type of furnace being used.  If you require the full technical details of bowing during the toughening process, please contact us to request a full copy of the standard.