The testing of mirrors

Mirrors may represent a safety hazard. Appropriate safety tests depend on the nature of the mirror.

The safety tests associated with domestic mirrors depends on the type of application. For example, it might be a wall-hanging mirror, or a mirror component that is installed within a piece of furniture (such as built into a wardrobe door), or a free-standing mirror to sit on the floor.

For a wall-hanging mirror there are at least two safety aspects that need to be considered. The glass in a large wall-hanging mirror could cause injury if the method used to attach it to the wall fails and the mirror falls down. It is recommended that a wall-hanging mirror is subjected to a SATRA ‘wall-hanging test’. This involves attaching the mirror to a wall following the supplier’s instructions using any fixings provided, and then exerting an additional downward force to the complete mirror for 48 hours to see if the fixing method fails. This additional force is a safety factor multiplication of at least twice the weight of the mirror face, to ensure integrity of the bonding to backer during possible overload conditions.

In addition, if the mirror in use is likely to be subjected to high temperatures or high humidity conditions, distortion in the frame and mount might lead to stress that causes the glass component to fracture – perhaps in a dangerous manner. Therefore, if, for instance, the wall-hanging mirror is for use in a bathroom, a suitable test is to place it in a high humidity test chamber, maintained at 23°C and 85 per cent relative humidity (rh) for 28 days. An inspection is then carried out to look for any signs of distortion, bowing or swelling, and any signs of backing adhesion failure. Loss of adhesive bond quality or loss of security would mean a failure unless there is more than one system holding the glass in position.

If the wall-hanging mirror is for use above a fireplace (for example in a living room), an elevated temperature test would be appropriate. It is recommended that the mirror should be placed on in a dry heat oven for eight days – four days at a temperature of 40°C followed by a further four days at a temperature of 50°C. After exposure, the mirror is again inspected as described above.

If the mirror is for use in a cool hall, then effect of elevated temperature is not so important – but the wall-hanging test described above would still be appropriate, especially if the mirror is heavy.

Standards for mirrors

There are few relevant standards for mirrors. Although withdrawn, BS 7449:1991 – ‘Specification for inclusion of glass in the construction of furniture, other than tables or trolleys, including cabinets, shelving systems and wall hung or free-standing mirrors’, provides recommendations for the design and construction of mirrors, but highlights no specific tests for them, except for an impact test in appendix A. BS 7449 is useful as it gives guidance on informative markings to be used on mirrors. European standard EN 14749:2016+A1:2022 – ‘Furniture. Domestic and kitchen storage units and kitchen-worktops. Safety requirements and test methods’ includes an impact test that is relevant to mirrors. For a mirror component that is installed (for instance, in a wardrobe door), this impact test in EN 14749 applies, but only if the mirror has no backing – that is, if it is not supported by a carrier board such as medium-density fibreboard (MDF).

For a free-standing (floor-standing) mirror, it is appropriate to use the stability test in BS 4875-8:1998 – ‘Furniture. Strength and stability of furniture. Methods for determination of stability of non-domestic storage furniture’ (a severe stability test), or EN 14749 clauses 5.4 and 5.5. If the mirror is more than 1m high, a stability test under 5.4 would apply.

The term ‘safety glass mirror’ is sometimes used. A safety glass mirror is made by adhering a special protective film to the back surface of a silver glass mirror. This prevents injuries in case the mirror is broken.

For any mirror, an adhesion-to-backing integrity test (see below) is a sensible way of checking that any failure would be a ‘safe’ failure. This integrity test is similar to the ‘fragmentation test’ utilised to check transparent glass. A hammer and metal punch are used to check that when broken, the glass of the mirror remains safely attached to the backing material, which may be a ‘safety film backing’.

As far as product marking is concerned, a sensible precaution would be to put appropriate warning labels on a mirror, such as ‘do not put hot objects against this mirror’, or ‘follow the supplied instructions when mounting the mirror on a wall’.

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