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.


Related projects

Head of a stranger, Egypt


Laser cleaning, desalination, preservation, 750 - 400 BC

Tomb of Augustin Holdt - Apothecary, St. Stephen’s Cathedral, Vienna


Leitha limestone, originally set in polychrome, 1512

Tomb of Hans Metzkher, St. Stephen’s Cathedral, Vienna


Solnhofer limestone, adneter limestone, 1546

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

South Tower Portal, St. Stephen’s Cathedral, Vienna


Entrance hall into the south tower, Madonna, 14th century

"Lackner Mount of Olives", St. Stephen’s Cathedral, Vienna


Relief in Auer limestone, 1502

Gothic Main Gate, Minoriten Church, Vienna I


Pointed arch portal with sculptures and reliefs of auer limestone, 1339

Romanesque Main Gate, Parish Church, Tulln, Lower Austria


Round arched gate with reliefs of apostles on the door posts, of limestone and quartz sandstone, 12th century

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

2007 - 2009

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

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

Palazzo Pubblico, Siena, Tuscany, Italy


Town hall and museum centrally located on Siena's former market square, the Campo, the venue for the famous horse races; construction start in the 13th century

Terracotta figure, Vienna


Terracotta figure, 19th Century

Lion of St. Mark from Vienna South Station, Central Station, Vienna


One of the two surviving, winged lions of sculptor Joseph Leimer. Overall, eight Venetian lions were on the gable attics of the four wings of the former South Station, 1873.

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

2022 - 2025

West chapel lower part ca. 1360 to 1395, upper part ca. 1400 to 1440, Side of the nave completed in 1440, Lobby of the bishop's gate around 1510, decorative pediment 1855/56 in imitation of the Friedrich pediment on the south side, restored in 1881

Straub epitaph, St. Stephen’s Cathedral, Vienna

2023 - 2024

Relief in Breitenbrunner limestone, ca. 1540

Related articles

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.

"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.

"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…

Once around the cathedral in 30 years


Only available in German.

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.

Further references

Title Location Client Year Technologies
Museum Carnuntum, fragments of sculpturesCarnuntum, Lower Austria Provincial Government of Lower Austria 1999
Heidentor Carnuntum, Roman altarsCarnuntum, Lower Austria Provincial Government of Lower Austria 1999
Mozart monument in BurggartenVienna Burghauptmannschaft Austria 2001
Parish church of Tulln, 10 epitaphs of sandstone and limestone on the outer facades, 16th - 18th centuryTulln, Lower Austria Diocese of St. Pölten 2007
Basilica Choir 1998-2001, Laser ProjectBad Deutsch-Altenburg, Lower Austria Archdiocese of Vienna 1999
Villa Plecnik Vienna, laser cleaning of Art Nouveau stuccoVienna Hietzing University of Applied Arts Vienna 2001
Ölberg relief, Parish church of Melk, 1502Melk, Lower Austria Diocese of St. Pölten, Parish of Melk 2002

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