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.