Technologies

Museum preservation

"Museum preservation", as opposed to restoration, means that an object is preserved in its current form. All measures are aimed towards preserving the piece authentically and passing it on to the next generation in an unadulterated condition. This basic principle is also firmly rooted in the 1964 Venice Charter, and is the central, internationally recognised guiding principle of historical preservation. In line with this principle, reconstructions and visual alterations are not even considered. Our specific experience and international recognition in this discipline means that there is always more work for us to do.

Laser Cleaning

Cleaning processes must not damage, and certainly must not destroy, original and valuable masonry surfaces.

For this reason, we have been using the ND:YAG laser technique to clean valuable stone objects for almost three decades. (St. Stephen's Cathedral, Vienna; Minorite Church, Vienna; Bad Deutsch-Altenburg Basilica, Lower Austria; Carnuntum Archaeological Museum, Lower Austria; Palazzo Pubblico, Siena, etc.)

The devices are powered by an yttrium aluminium garnet (YAG) rod, which is a carrier of amorphous glass treated with neodymium (Nd.), a mineral that allows photons (light quantums) to be produced in the required wavelength (1064 nm = infrared). The key advantage of this technique is the short duration of its light pulses, at less than 10 ns (nanoseconds). Each pulse creates a shockwave in the layer of deposit and dirt. The micro-resonance causes the dirt to become dislodged without damaging the underlying stone because this reflects the beam.

The stripping properties can be adjusted precisely, which also means that it is possible to retain "patina layers" on the surface caused by age.

Vacuum Conservation Method

(Europa Patent Erich Pummer GmbH no. 1295859)

Stone conservation is necessary in order to stop the degradation of masonry that limestone and sandstone monuments are particularly at risk of due to frost and acid rain.

The patented "vacuum-circling strengthening process" (Europa Patent Erich Pummer GmbH no. 1295859) allows monuments, stone sculptures, facades and other free-standing and weathered objects to be preserved either in-situ or in the workshop.

Thanks to this technology, a basic principle that has been sought in stone conservation for decades can be realised: namely, that the right quantity of new bonding agent is applied to the damaged object and, above all, is injected deep into the stone. This is fundamentally important since simple surface treatment can cause the sort of follow-up damage that is all too widely seen. This damage includes cavities of just a few millimetres that become chipped after a few years, causing parts of the original surfaces of the artwork to be irreparably lost. The objects to be treated, which can be virtually of any size, are shrink-wrapped in airtight solvent-resistant film. The remaining air trapped inside the film and within the porous cavities of the stone is then drawn out with the vacuum-circling preserver so that a vacuum is created in the object itself. After a relative vacuum of 300–900 mb has been achieved, the appropriate strengthening agent (silicic-acid ester or acrylic solution) is injected via a precise dosing system, and distributed evenly and deeply into the stone thanks to the low pressure. The open pores and badly damaged areas are filled first, while the remaining pores and capillaries in the healthy and sound material take slightly longer to fill until, finally, the stone has been restored back to its even and original strength.

Effective and efficient demineralisation can be achieved using the same techniques by rinsing with demineralised water. More information in the article: "The cleaning power of water"

This conservation method is already widely accepted throughout Europe by scientists and monument conservationists. Our work has taken us beyond Austria into Germany, Croatia, Hungary and even Azerbaijan.

Polychromy

Today, the original colours of decorated stonework are often not easy to identify at first glance, even though it was a very common and widespread tradition, stretching from the beginning of the Classical period through the Middle Ages and right up to modern era, to create more lively and expressive pieces. In the 19th century in particular, the catastrophic trend to strip all types of objects back to their basic material meant that countless works of art were robbed of their polychrome in order to bring the building material, usually stone, to the fore. Nowadays, restorers use scalpels, magnifying glasses and microscopes to search meticulously for the remains of the original versions so that they can document, preserve and – in some cases – reconstruct the objects.

Knowledge of the pigments and binding material used is the basic requirement for a serious examination of the object from an art history perspective, using these important artistic and conservation techniques.

Copy

A "copy" is the result of reconstructing an original. This term can be used for almost all everyday objects but, in connection with historical preservation, mainly refers to reproductions of artworks. There may be many reasons for creating a copy:

Multiple copies may be used as a way to advertise the original.

The copy may be used as an alternative to a lost original.

The copy may be put on display instead of a valuable original.

Copies can be made from the same material as the original, but many other alternative materials are also possible. Materials available to us include stone, artificial stone, concrete, plaster, ceramic, plastic, wood and metal.