Protection for the world’s cultural heritage

Polycarbonate sheet protects the Casa del Centenario in Pompeii against weathering and environmental damage

It was in 1879, exactly 1,800 years after the city of Pompeii had been buried under an avalanche of volcanic ash, that archeologists uncovered the magnificent Casa del Centenario. Of course, at that time they could scarcely have imagined what conservation problems this discovery would present to subsequent generations of scientists.

The most important challenge today is to protect this archeological treasure against damage caused by weathering without removing it from its location and without destroying the overall setting visually or structurally. With collapsed roofs, missing side walls and wall paintings exposed to the damaging effects of weathering, there was an urgent need for a protective material combining a high degree of resistance to wind and weather with transparency and light weight.

When it became clear that the protective materials initially used - tiles and Eternit asbestos cement roofing sheet - were not up to the task, and that glass also had to be ruled out on account of its weight, conservationists turned to solid and multi-wall sheet made of Bayer’s Makrolon polycarbonate. The results were gratifying: Makrolon monolithic and multi-wall sheet based on high-quality raw materials offered not only low weight and good light transmission, but also an exceptional level of impact strength.

The project concentrated on the Casa del Centenario on the Via di Nola - an imposing building set around a double atrium and featuring an inner courtyard on the north side enclosed by a double row of columns. The inner section contains a luxuriously decorated nympheum, baths with a mosaic fountain and a covered walk. The basement houses several rooms with hearths, a private heated bathing area and a number of rooms possibly used for erotic entertainment.

Ideal protection with multi-wall sheet

A protective structure made of Makrolon shields one corner of the main atrium. This inner courtyard was originally completely covered by a roof, with the exception of an opening above the impluvium - a basin to receive rainwater. The partial reconstruction of the covering over the atrium aids a visual appreciation of the restoration work and could constitute the first phase in a possible complete reconstruction of the roof.

The framework for the roof is made of aluminum and is designed as a temporary structure that can be dismantled and re-erected on another part of the site at any time. The roof itself is constructed using Makrolon multi longlife multi-wall sheet and is supported on four pillars. The two triangular roof surfaces are angled down towards each other, with the resultant valley creating a sort of rainwater gutter. Rainwater running off the roof collects here and is then channeled into the impluvium via the central, diagonal conduit. Bronze-colored Makrolon multi longlife multi-wall sheet was used here.

The tinted polycarbonate sheets filter and subdue the sunlight, thereby recreating the effect of the original roofing and at the same time providing protection against rain. The manufacturers Makroform guarantee the Makrolon sheets for ten years against damage caused by UV radiation and hailstones.

Another cover made of bronze-colored Makrolon multi longlife sheet protects the lararium, the shrine of the household gods. This replaces the previous antiquated roof structure, but is supported on the existing iron beams. The lararium, incidentally, is the home of the famous painting "Bacchus and Mount Vesuvius", currently housed in the Archaeological Museum in Naples. A copy - protected by Makrolon sheet - is on display at the Casa del Centenario.

Transparent multi-wall sheets are also used as vertical protective shields to seal large openings in the walls and help prevent the ingress of rainwater.

Solid sheet: Mobile protection for delicate works of art

Paintings and inscriptions are preserved and protected by the use of Makrolon mono dura solid sheets to seal window apertures and prevent disfiguring graffiti. The upper sections of these sheets are hinged to enable them to be lifted up, thus providing access to the protected sections of the paintings at any time.

Glass would have been quite unsuitable for this purpose because of its weight. A 4 mm-thick pane of glass weighs 10 kg per m², whereas a Makrolon mono sheet of the same volume tips the scales at a mere 4.8 kg. The light transmission of a transparent plastic sheet varies from 86 to 78 percent, depending on its thickness. Makrolon mono solid sheets are comparable to Makrolon multi sheets as far as impact strength and non-splintering characteristics are concerned.

The Makrolon mono dura polycarbonate sheets used in Pompeii are guaranteed for 10 years against fracture and for 5 years against delamination and the ravages of weathering. The sheets are provided with "dura" surface treatment on both sides to improve their resistance to abrasion, chemicals and UV radiation.

With these exceptional properties, Makroform demonstrates its suitability for the conservation of ancient archaeological sites and its potential for technological innovation - both of which play a major role in preserving irreplaceable cultural treasures like Pompeii for future generations.

© 2001 Bayer AG, Germany