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.



Related projects

Baroque fountain, Schönbühel Palace Park, Wachau, Lower Austria


Fountain pool made from wachauer marble, sculpture from limestone

Cascade fountain, Nymphs, Belvedere Palace Park, Vienna


Baroque fountain, sculptures of shell limestone from Zogelsdorf (larger than life-size), 18th century

Holy Trinity Column, Krems an der Donau, Lower Austria

2006 - 2007

Baroque monument in limestone from Zogelsdorf, Joseph M. Götz, 1736

"Carolus Monument" at the Semmering Pass, Lower Austria, Austria

2006 - 2008

Design by J. E. Fischer v. Erlach, 1728

Albertine choir, west facade, south tower, St. Stephen’s Cathedral, Vienna

1997 - 2024

Medieval choir, Romanesque-Gothic west facade with heath towers, benefactor statues, tombs, South Tower

National Library, Hofburg, Vienna

2008 - 2009

Attica monument sculptures in limestone, 18th century

Mohammed Mosque, Baku, Azerbaijan


limestone, UNESCO World Heritage Site, 11th century

East Portal Facade, Benedictine Monastery, Melk, Lower Austria


Jakob Prandtauer, obelisk portal with statues and gable attic of shell limestone

Founders’ Statues, West Facade, St. Stephen's Cathedral, Vienna

2007 - 2009

Statue of benefactor, Catherine of Bohemia, life size, 1870

Attica Statues, 67 pieces, Schloss Schönbrunn, Vienna

2009 - 2012

67 Attica sculptures and vases on the main building, entire north and east wing, life size, 1730

South side of the nave central section, St. Stephen’s Cathedral, Vienna

2012 - 2021

Eligius chapel around 1360 - 1400 and Bartholomew chapel until 1437, Singertor 1440 - 1450, restored 1894 - 1896, Friedrich pediment 1430 - 1440, restored 1982ff and 1928, decoration of other pediments 1853/1854, restored 1882ff

Sculptures on Facade, City Hall, Korneuburg, Lower Austria


2 Statues with baldachins, 1895

Main Facade, St. Michael’s Church, Munich, Germany

2010 - 2011

4 figures

Busts, Town Hall Square, Vienna


Larger than life statues, 1900

Prelate Yard, Attica Statues, Melk Monastery, Lower Austria

2008 - 2009

Attica monumental sculptures, limestone, 18th century

Late Baroque Tomb, Neustädter Cemetery, Dresden, Germany


Late Baroque Tomb of Cotta sandstone, 1731

Wedding Fountain, Hoher Markt, Vienna


3 larger than life statues and 3 reliefs, carrara marble, 1732

Pillory column Hollenburg „Rolandssäule“, Pillory area Hollenburg, Krems, Lower Austria


Sculpture made of limestone from Zogelsdorf, column and steps construction made of regional conglomerate rock, 1590

Neo-Gothic Madonna with Child, Stuckgasse, Vienna

2011 - 2015

Neo-Gothic Madonna with Child – Loretto sandstone, after 1832

Marian column, Tulln, Lower Austria

2013 - 2015

Baroque Marian column in limestone from Zogelsdorf, 1748

Family crest, Greillenstein Palace, Lower Austria

2016 - 2017

Renaissance family crest made of limestone from Zogelsdorf

War memorial, Germersheim, Germany


Monolithic lion sculpture, 210 cm hight and barrel-shaped pedestal, 65 cm hight, diameter 120 cm, Historicism

Benedictine Abbey, Frauenzell, Germany


Portal west wing, column shafts

Related articles

Lower Austria WKO Innovation-Award creatively into the future


"Erich Pummer GmbH, for its innovative vacuum preservation technique in works of art made of stone, was awarded in the category of design and crafts"

Innovation Award in architectural conservation


only available in German

"Monumento Salzburg 2012"


Successful start for Monumento 2012 The first trade fair for conservation of historic monuments in Salzburg For three days, the spirit of times long passed imbued the halls of Messezentrum Salzburg. Experts and enthusiasts of historical artifacts enjoyed the opportunity to explore the…

The cleaning power of water


DBU Project Dresden – Sponsorship project of "German Environment Foundation 2013“ "Innovative method to strengthen complicated preservable environmentally damaged sandstone monuments and numeric geomechanic simulation of the risks”

"Monumento Salzburg 2014"

16/01/2014 - 18/01/2014

Also this year, we enjoyed many visitors to our booth at the Monument in 2014 and would like to thank you this way for your interest.

Vacuum-Circling Process: A Innovative Stone Conservation Method

06/09/2016 - 10/09/2016

Science and Art: A Future for Stone: Proceeding of the 13th International Congress on the Deterioration and Conservation of Stone, Volume 2. Paisley: University of the West of Scotland. S. 931ff; by Erich Pummer

The Bernhard Remmers Award 2010


only available in German

The trinity column of Krems – Research · Preservation · Restoration


Special award for Innovation - sponsored by the German Foundation for Monument Protection

VAC-demonstration at Arsenal


Vienna „Universität für angewandte Kunst“ (University of applied arts) field of study – stone conservation

Memorial Day ("Tag des Denkmals")


The Studio Erich Pummer opens at 10 AM its doors for those who want to learn about the latest techniques in stone restoration and preservation.

Intelligent Stone Conservation

01/03/2015 - 31/03/2015

Only available in German

Application of Ethyl Silicate Based Consolidants on Sandstone with Partial Vacuum: A Laboratory Study

06/09/2016 - 10/09/2016

Science and Art: A Future for Stone: Proceeding of the 13th International Congress on the Deterioration and Conservation of Stone, Volume 2. Paisley: University of the West of Scotland. S. 955ff; by H. Siedel, J. Wichert and T. Frühwirt

Bernhard-Remmers-Award 2010


"For his work with the vacuum consolidation (VAC) Erich Pummer was honored a special prize for innovation in monument preservation, donated by the German Foundation for Monument Protection."

Stone restoration on Seidenstraße


When a stone restorer from Wachau, Austria, stone carver and stonemason named Erich Pummer is invited along with his team to Azerbaijan, one can assume its principals have been well informed.

Consolidate with vacuum

01/10/2007 - 01/10/2013

Consolidation of natural stone always goes back to one question: How do you transport the consolidant agent into the depth of the stone? New perspectives are opened by a vacuum-circuit process by which first practice experiences have already been gained. by Erich Pummer

Stone conservation / actual


Who among the stone restorers is not aware of the problems when confronted with severely damaged objects that can not be preserved in the long run with traditional methods.

Ethyl-silicate Consolidation for Porous Limestone Coated with Oil Paint – A Comparison of Application Methods

06/09/2016 - 10/09/2016

Science and Art: A Future for Stone: Proceeding of the 13th International Congress on the Deterioration and Conservation of Stone, Volume 2. Paisley: University of the West of Scotland. S. 889ff; by M. Milchin, J. Weber, G. Krist, E. Ghaffari, S. Karacsonyi

Once around the cathedral in 30 years


Only available in German.

Further references

Title Location Client Year Technologies
Holy Trinity column Tulln. Total degradation vacuum strengthening of four angels, 18th centuryTulln, Lower Austria Municipality of Tulln 2008 - 2009
Marble epitaph, Parish church, 1527Tulln, Lower Austria Parish office of Tulln 2004
Parish church Hollenburg, 5 epitaphs. vacuum consolidation v. 3 Limestone Epitaphs, 16th - 17th centuryHollenburg, Lower Austria Parish of Hollenburg 2009
Holy Cross Parish church of Gutenbrunn 3 sculptures, 4 vases on the east facade., 18th centuryGutenbrunn Heiligenkreuz, Lower Austria Holy Cross Parish office Gutenbrunn 2011
Ernstbrunn Palace, colossal vases, Abrasive sandstoneErnstbrunn, Lower Austria Reuss'sche goods Directorate Ernstbrunn 2006
Baroque pediment group guest wing North and West 4 sculptures, 4 vases, 3 ??PuttisAltenburg Monastery, Lower Austria Monastery of Altenburg 2005 - 2006
Maria column - Immaculata, Pauline church - Favoritenstraße, vacuum consolidationVienna I Magistrate of Vienna MA 7 2008
5 pcs. sculptures of Laas marble, 19th centuryMoos Palace, Bavaria, Germany Palace administration Arco-Zinneberg 2010
Balcony sculptures, four seasons, Loretto LimestoneRingstraße, Vienna Haselsteiner Family private donation 2010
Gothic baptismal fontNussdorf ob der Traisen, Lower Austria Parish of Nussdorf 2011
St. George’s fountain, reed sandstoneRothenburg o.d. Tauber, Germany Stone restoration Bauer-Bornemann, Bamberg, Germany 2005
Holy Trinity column, Sculptures, shell limestone, 18th centuryTulln, Lower Austria Municipality of Tulln 2008 - 2009
Loretto, Madonna, Loretto limestoneLoretto, Burgenland Bundesdenkmalamt Arsenal 2008
Schönbrunn Palace, column staircase, desalination, shell limestoneSchönbrunn Palace, Vienna Studio Gurtner Vienna 2007
Holy Trinity column, Sculptures, LimestoneOsijek, Croatia Hrvatski Restauratorski Zavod, Croatia 2009
Mathias church, original pillar, LimestoneBudapest, Hungary Remmers Ungarn Kft. 2007
Parish church, coat of arms cartouche, reed sandstoneKersbach, Germany Monolith GmbH, Bamberg 2010
Madonna Walfahrts church, Adneter red marbleMaria Taferl, Lower Austria Roman catholic Parish office Maria Taferl 2012
Johannes Cloister, Desalination of brick masonryStralsund, Germany Urban Renewal Society Stralsund, Germany 2012
Parish of St. Jacob, Olive figures, desalination, reed sandstoneRothenburg o.d. Tauber, Germany Stone restoration Bauer-Bornemann Bamberg, Germany 2013
Neogothic Madonna sculpture (Maria with child), 1823Stuckgasse 9, 1070 Vienna IMV - Immobilien Management GmbH 2013

Our website enriches your online experience with personalized cookies. Tailor your settings, but be mindful that this may affect certain features..
Explore more details in our privacy policy and about.

Our website enriches your online experience with personalized cookies. Tailor your settings, but be mindful that this may affect certain features..
Explore more details in our privacy policy and about.

Your cookie preferences have been saved.