Wall Paintings
Wall paintings or murals can be found in churches dating from the Middle Ages onwards. They were a simple and effective means of decoration. Wall paintings can be an important and treasured part of the decoration of a church, featuring both figurative and decorative motifs. Due to changing taste and theology most were overpainted in a later period and medieval churches may well have rare survivals hidden under layers of paint. Any redecoration schemes need to account for the possibility that paintings may be discovered in the course of the work.
Wall paintings are paintings applied to a prepared wall surface. This may have been done in several techniques. The most famous, a true ‘fresco', i.e. the application of paint, consisting of pigments mixed with water or limewater, onto a fresh lime plaster which bonds the pigments as it sets/dries, is relatively rare in Britain. The preferred method here in the Middle Ages was ‘mezzo fresco' or ‘lime painting' where paint was applied to recently applied plaster which bonds the pigments as it sets. The ‘secco' technique involves the application of paint over dried true fresco or lime painting or plaster.
Causes of damage
Wall paintings can be painted onto the walls, ceiling and other architectural elements such as columns. Therefore, they closely depend on the condition and regular maintenance of the building's fabric. Water is the chief cause of damage to wall paintings and any water ingress can cause long-term damage by salt crystallization.
Fluctuating relative humidity causes repeated salt dissolution and crystallization as well as repeated swelling and shrinking of organic components. Both cycles can cause the fracture and peeling of the paint. A high relative humidity encourages microbiological growth on surfaces. The heating system in the church may contribute to an unsuitable high humidity level. The special requirements of wall paintings need to be taken into account when considering installing a new heating system.
Figure 1 Flaking paint
Structural damage to the building can cause cracks and bulges in a wall painting. Wall paintings are very vulnerable to knocks and abrasion which can cause severe damage.
Fungi, algae and lichens feed on the organic components of the painted surfaces and accumulated dirt. Their presence disrupts and stains the paint and underlying layers of a painting. The urine and faeces of bats can also stain wall paintings.
Light-sensitive pigments can fade over time and organic paint media and varnishes may discolour. Damage and deterioration may also be due to inherent problems such as poorly applied materials or past repairs such as revarnishing which absorbs dirt.
Signs of damage
Part of good maintenance is the frequent monitoring and checking for signs of damage. Signs of damage to wall paintings include:
- loss of paint or plaster
- debris on the floor underneath the painting
- flaking paint
- fresh cracks
- new bulges
- salt crystals,
- stains
- blooming (a white, cloudy layer on the surface)
- dirt
- mould, algae, lichen growth
Maintenance
As water can be the cause of a number of these, it is important to keep the building in a good state of repair and regularly check the roof and the rainwater goods and drainage. If water stains appear on a wall painting or in its vicinity it is vital to find the cause and stop the leak as soon as possible. An accredited conservator who will be able to take emergency measures to protect the wall paintings needs to be called as soon as possible.
As wall paintings are highly vulnerable to abrasion the surface should never be touched and accidental contact should be prevented. Judiciously positioned furniture may help, however, care should be taken that the furniture itself does not touch the wall. Nothing should ever be screwed, fixed or nailed to the surfaces of a wall painting.
The environmental conditions, including light, temperature and relative humidity levels, should be measured by an accredited conservator to establish their suitability and included into a condition report. A stable environment without dramatic fluctuations in heat and humidity is ideal. Wall paintings are moderately light-sensitive and should be protected from direct sunlight if possible.
A conservator's condition report should also contain advise on regular maintenance in the form of a care plan tailored to the specific wall painting. The paintings should be regularly (and ideally at least quarterly) visually inspected for any signs of damage. Regular photographing can be useful in order to assess whether a wall painting is fading or just becoming dusty.
Wall paintings should be dusted and cleaned by an accredited wall paintings conservator. Do not attempt to include them in the parish's normal cleaning regime.
During building work or redecoration the wall paintings should be appropriately protected, following specialist advice.
If small parts of paint or plaster have fallen off the wall they should be collected by hand and kept in an envelope or flat box. An accredited conservator should be consulted who will ascertain the cause and may be able to reattach the parts.
November 2007
Further Information
ICON, Care and Conservation of Decorative Schemes and Surfaces
(available on the Conservation Register website)
