Behind the scenes: Installation and removal of mirrors for the British Galleries project
During the course of work undertaken in the Spring of 1999 on the British Galleries project, it was necessary to remove and redisplay a number of large, fragile, highly decorated gilt framed mirrors. The handling problems posed by such a project were considerable. When handling anything of this sort the risk of damage to delicate high-relief carving and tracery can be quite high, as there are usually few, if any, handling points which do not involve applying pressure to fragile elements of the frame.
From a conservation perspective, the ideal solution would be to avoid any movement and handling altogether. Needless to say, this is not a feasible concept in the museum world. But as technicians concerned with conservation issues, we like to keep physical contact with objects to a minimum.
The Use of Backboards
One answer to the problem is to fix the object to a backboard upon which it can remain permanently, whether in storage or on display. This effectively eliminates all physical contact with the object itself, and transfers the stresses of lifting and moving directly to the support and away from the fragile elements of the object. This not only improves the ease with which a delicate object may be stored or installed, but also facilitates rapid removal in the event of emergency.
A further benefit of backboards is the provision of rigidity to objects that may have suspect structural integrity. This is especially helpful for objects made up of various component parts, where fixings between those parts may be insecure. The advantage to an object where the major component is glass is obvious. Multi-paned mirrors such as those moved for the British Galleries demonstrate this need very plainly.
One of the disadvantages of fixing to a backboard is the resultant increase in weight. This will obviously increase the difficulty of manual handling, often necessitating the use of mechanical lifting equipment. It has also been found that solid backboards are only advantageous up to a certain size. When the board becomes bigger than about 1.5m x 2m it begins to flex significantly under its own weight defeating the objective of providing rigidity, and increasing the risk of damage to the object. Adding structural support/framing to the backboard can reduce this distortion, but adds further weight.
Another significant disadvantage is that the backboard becomes a visible part of the object's display environment. This is something which, at times, many gallery designers and curators do not wish to contemplate. However, technicians still have to face up to the problems of handling/ moving/ hanging these objects safely and without damage; so, a viable alternative must be found.
Removal of the mirror using the 'batten method'
A successful solution to the disadvantages of using a backboard was developed during the redisplay project for the British Galleries. Several very ornate gilt-framed 18th century mirrors had to be moved.
The first stage in the removal operation was to replace the screws fixing the object to the wall with extra long ones. These were done, one at a time in rotation, so the object remained fixed to the wall throughout. Each screw went into the same hole as the one it was replacing. However, rather than being driven fully home, the last 20-25 mm was left protruding beyond the thickness of the object/mirror plate.
The object was then gently eased away from the wall onto the ends of the screws. This created a gap between the object and the wall, allowing lengths of 100mm x 25mm battens to be passed up behind and aligned with the mirror-plates/fixings on the object (image 2). These battens needed to extend some distance beyond the top and bottom of the object in order to create 'handles' and to facilitate the fixing of cross-bracing at a later stage. Each fixing/plate on the object was then attached to one of the upright battens. Again, this was done in rotation by first removing one of the long screws, inserting the batten behind the plate and fixing in with a 20mm screw. The next fixing was undone from the wall, the same batten then rotated into position behind it, a screw fixed through the plate into the batten, and so-on until all plates/fixings are connected to the 100mm x 25mm battens. Care needs to be taken in situations where there are multiple fixing points so that maximum strength is maintained. If an object has been in the same place for decades it is not uncommon to find some mirror plates which are very loosely connected to the object, or which have been connected to a very fragile area. If it is not possible to align the boards behind all of the fixing points on the object, it is important to select the plates/fixings which will offer the most support to the object while it is being handled.
During this process it was necessary for technicians to hold the battens to the wall and begin to support the weight of the object. When all of the fixing points were transferred from the wall to the battens, the object was lowered to the ground (using the battens to 'handle' the object). Once the object had been lowered, cross-braces were added to the 100mm x 25mm battens for extra structural support (image 3). This framework was then used to handle and transport the object without the need to touch any sensitive or fragile areas around its edges (image 4). It is also possible for this whole assembly to be fitted into a carrying frame, which will further improve rigidity/stability during movement over any distance and, if necessary, will vastly improve conditions for safe storage.
It is possible to arrange the battens and cross bracing in such a way that it allows for the use of various items of lifting equipment. This can be essential if the object being removed is of considerable weight and would be too difficult to control manually. The use of lifting equipment can also be particularly useful in the process of re-hanging the object. It allows for much more careful and accurate positioning than manual handling as there is no concern over the time taken to hold the object in position. It is simply a matter of resting the support frame on top of the lifting device and raising it to the desired height.
Re-hanging the mirror
When the object needed to be refitted to the wall, the process for removing it was reversed. First the whole assembly (object and support) was secured to the wall using long screws. The screws were withdrawn one at a time in sequence to allow the removal of the support frame, and then driven home to secure the object in position. Care was taken to ensure that none of the crossbracing ws fixed from the back, which would have made it impossible to remove. Thus the objects were removed, transported, and re-hung with relatively little physical contact and can now be seen looking as they were originally intended.
Mirror, after Thomas Chippendale
After Thomas Chippendale
Carved and gilded pine, mirror glass, brass
Museum no. 2388-1855
Mirror, about 1800. Museum no. W.85-1926
Convex mirror, pinewood, gilded, with convex glass
Museum no. W.85-1926
Mirror, attributed to Thomas Johnson
Attributed to Thomas Johnson (1714- about 1778) by Helena Hayward
Pier glass, carved and gilded wood
Museum no. W.23-1949
i. Movement of each object would be preceded by a detailed conservation condition report before any handling is carried out.
ii. Fragile frames that are likely to be moved on a fairly regular basis, such as those for touring exhibitions, are best fitted on to a rigid backboard if size and weight will permit, to reduce risks encountered each time the frame is taken down.