Salvaging Vandalised Rock Art at Domboshava National Monument in North-eastern Zimbabwe
Domboshava cave lies 35 kilometres north-east of Harare and was proclaimed a national monument in 1936, covering only 1 acre. The physical boundary of the site was extended in 1996
to cover 300 hectares. The proclaimed area now encloses rock paintings, late Stone-Age deposits, a geological tunnel (which has acquired cultural significance through time), sacred
forest, spectacular granite geological formations and a buffer zone for management purposes. An Archean green stone belt surrounds the Domboshava batholith (Lister 1987; Baddock
1991; Stocklmayer 1978). Generally a dissected and relatively undulating igneous complex (comprising series of gneiss tonalite-granadiorite plutons) characterises the Chinamora area
occupying 1200 square kilometres.
Several values placed on the Domboshava rock art site were used to justify its nomination to the National Monuments list of Zimbabwe. These include the scientific, living
traditional, geological, educational, social values and many others. The site has more than 146 identifiable individual rock paintings, executed in red and brown pigments. The shelter also
has scatters of Stone Age deposits attributed to Stone Age communities; however, no excavations have been done to place these deposits into Zimbabwean Stone Age chronology.
The living traditions revolve around a rainmaking ceremony, which is performed once a year at the site. As an educational resource, the site can be used across the school curriculum in
the fields of art, geography, history and geology, among other subjects. Therefore, the management of the cultural site, as well as any restoration or conservation work, should respect
the values placed on the site. Otherwise it becomes a mis-management or ‘mis-restoration’ of values, which could lead to the desecration of the authenticity or the totality of
this Domboshava national monument.
Vandalisation and Condition Assessment of Domboshava National Monument
Domboshava cave was vandalised on the eve of 14 May 1998. The incident was reported by law enforcement agents to National Museums and Monuments of Zimbabwe (NMMZ) on 15
May 1998. An inspection of the Domboshava site and others within the area was undertaken, in order to establish the extent, type, and nature of the vandalism. Photography was
extensively used to document the graffiti.
The graffiti is one of the most severe, distressing and depressing damages known to have happened at any rock-art site in Zimbabwe, apart from Pomongwe cave which was
damaged by an application of linseed oil around 1965. At Domboshava cave, a dark-brown enamel (oil-based alkyd) paint was used to obliterate paintings. The dark-brown paint covered
approximately 75% of the painted surface and about 5% of the unpainted surface. This excludes the extreme left and right sides of the painted surface, as well as the upper and top most
levels of the cave.
Out of the 146 identifiable individual paintings known to exist in the Domboshava cave, approximately 65-70% were obliterated with the dark-brown oil paint. About 90% of all
the human figures were completely obliterated; 52% of the animals remained unvandalised on the extreme right side of the painted surface and on the upper-parts, which could not be
reached. The identifiable abstract and plant figures were not vandalised at all.
As a starting point, the paint used to obliterate the rock paintings at Domboshava cave was analysed by a leading Zimbabwean paint-producing company. The aim was to determine the
chemical composition of the paint (especially the type of binder) used to obliterate the rock paintings, and subsequently identify chemicals that are likely to remove it without removing
the rock paintings. Flake samples with traces of the offending paint were collected and sent for physio-chemical analysis by a leading paint producing laboratory. The result showed that
it was modified brown enamel (alkyd resin) paint. Technically this kind of painting takes between 18-24 hours to dry after application.
An analysis to determine the nature of the rock affected by the graffiti revealed that the stone material is a garnet with strong lamination. Granted that the rock samples analysed
were representative of the general situation, the rock surface appeared very friable and extremely sensitive to any kind of mechanical touching. However, this could be subjective,
because the samples were collected from the lower levels of the cave, which probably would not be representative of the nature of the entire Domboshava granite outcrop.
The information gathered from the physio-chemical analysis of the graffiti, and the nature of the rock affected, became the basis for formulating cleaning trials. The aim was to
test the effectiveness and impact of all the possible cleaning methods on the paintings and the stone itself. Several cleaning methods, ranging from mechanical to chemical, were tried
over nine months. Areas affected with graffiti but without rock paintings were used for the trials, with the exception of one ‘sacrificial’ cleaning trial done on a section with rock paintings
at the time of making a final decision. Generally the cleaning trials were confined to the lower levels of the cave.
Mechanical cleaning methods
A mechanical method of removing the graffiti was initially attempted. Several instruments were tried, such as blunt and sharp plastic knives and scrapers. The results were not
satisfactory, because these instruments failed to conform to the rugged surface of the rock face. The cleaning was not systematic and could not remove the graffiti. There was also a risk
of scraping both the graffiti and the rock paintings if sharper implements were used.
Solvent based cleaning methods
A lacquer thinner, a chemical constituted by benzene and lead (or a mixture of petroleum and benzene) was tried. It is usually used as a solvent in the painting industry. The thinner was
poured over the graffiti, then cleaned with a soft brush and distilled water. Instead of removing the graffiti, the lacquer thinner converted the brown enamel paint (graffiti) to a blackish
paint, which started to spread over the rock surface, further obliterating the surface. The conclusion was that the lacquer thinners could not clean this kind of graffiti.
Acetone (CH3COCH3 - dimethyl ketone), a colourless and inflammable solvent with a sweetish odour was applied in a manner similar to the lacquer thinner. The results failed to remove
Paint stripper, mainly constituted by methylene chloride (CH2CL2), was used as the last option. It was evenly applied in its thick jelly-like form and allowed 5-10 minutes to settle on the
surface with graffiti. A soft brush and distilled water were used to scrub off the thick jelly. The paint stripper successfully removed the graffiti leaving the rock patina visible but a little
shiny. In other sections that were not thoroughly rinsed with distilled water, a glossy appearance could be seen. It was concluded that a thorough rinse of all the paint stripper remnants
was important to avoid leaving ugly stains, which might contain damaging salts that could eventually destroy the works of art. It was therefore suggested to use Toluene (C6H5CH3) to
rinse the surface. The combination of Toluene and paint stripper appeared to be effective in removing the graffiti and avoiding the shiny residues of paint stripper.
‘High Tech’ cleaning methods: laser cleaning
The Nd: Yag laser cleaning method was used on samples with traces of graffiti but without rock paintings. Although the cleaning yielded positive results, it must be mentioned that given
the original rock paintings contain a wide range of brown to red pigments, colours synonymous to that of graffiti, it becomes obvious that the laser could either remove or alter the
original rock paintings. Therefore it was a risk to try this method in situ.
Several public lectures and consultations on these trial results were made within and outside the borders of Zimbabwe. On the basis of the results of the cleaning trials and
extensive consultations, a combination of the industrially produced paint stripper and toluene were recommended to clean the graffiti.
The Conservation Process
With patience and understanding of the principles involved in cleaning graffiti of this nature from rock paintings, the ‘mouth to mouth resuscitation’ process commenced in
September 1999. The cleaning exercise was divided into three phases, as the cave was divided into three sections. The conservation team cleaned the left side first, then moved to the
central section and eventually the right section. Before moving to another section, the team had to take a four-month break to monitor any developments on the area cleaned and
continue carrying out consultations with other experts. The success of the project hinged on following proper conservation processes and application of the recommended chemicals
within the limits of the technique chosen. In this cleaning exercise, we sought a complete removal of all the graffiti, given that both the rock paintings and the graffiti shared the same
shades of brown colour. Very soft artists’ brushes, trimmed to thumb-nail size, were used to clean 10 sq cm at a given time. Protective clothing was worn to safeguard the health of the
conservation team. The cleaning exercise thus spread over 1.5 years to allow continuous monitoring and modification of the method if need arose.
Results of Cleaning
Graffiti was successfully removed using the described method. The rock paintings are now very visible. The paintings were not affected because of the silica encrustation process over
several decades. Over the years of exposure, a silica crust develops on top of the rock paintings, to form a natural protective coating that is very difficult to remove. Paint stripper or
Toluene does not easily remove this silica crust. As such, the paintings were expected to remain visible after the cleaning. It is important to note that the fragile rock patina survived the
cleaning exercise. But one cannot rule out that it might have been partially removed, but the degree is less obtrusive compared to other areas not affected by the graffiti. The cleaning
exercise also removed thin layers of dust that had accumulated over the years, thereby exposing some figures that could not be seen very clearly before.
The vandalism of the Domboshava rock-art site posed and still poses a great conservation and management challenge to National Museums and Monuments of Zimbabwe. It is very
difficult to remove a commercial paint applied on any cultural site. The success of this conservation project, particularly given the nature of the graffiti and chemical used, cannot be
guaranteed as the after-effects are usually noticeable only after long periods of time. This fear brings us to the medical procedure: patient resuscitation. A person who has
‘collapsed’ or fainted due to a certain health condition, can be temporarily or permanently brought back to life through mouth to mouth resuscitation or using an oxygen breathing
machine. What happens after this resuscitation is beyond the means of the resuscitator, because many uncontrollable biological factors relating to a particular health condition come
into play. At Domboshava National Monument, rock paintings were given a new lease of life through the cleaning exercise. But whether it is a long or short-term lease of life is difficult
to tell, because of uncontrollable in situ factors that affect both the rock and the art. What is important is that an attempt was made to bring back the beauty of the rock
paintings, and a continuous monitoring process has been put in place. This process relies on a comparison of photographs taken, before, during and after the cleaning exercise. As such,
periodic reports will be produced.
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Curator of Archaeology, National Museums and
Monuments of Zimbabwe