SECOND ENGAGEMENT AT BERLIN CATHEDRAL
It has been undergoing extensive restoration for many years: the Berlin Cathedral in the heart of the capital. This is the second time that Kärcher has been involved in the facade restoration of the building as part of its cultural sponsorship.
Prophet figures get special cleaning from Kärcher
It has been undergoing extensive restoration for over four years: the Berlin Cathedral in the heart of the capital. Now Kärcher has become involved in the facade restoration of the building for the second time as part of its cultural sponsorship. After cleaning the prominent southwest tower in 2020, Kärcher, in cooperation with the cathedral's construction office, subjected the figures of the prophets Moses and John the Baptist to a comprehensive restoration cleaning.
"We are very pleased that Kärcher has once again agreed to support us in the mammoth task of restoring the façade of the Berlin Cathedral. Even if it doesn't appear so at first glance - the entire facade of the cathedral is in a state in need of restoration. Maintenance requires many helping hands and extensive support, and we are very grateful to everyone who contributes something to this important task," says Cathedral Master Builder Sonja Tubbesing.
Cleaning in two steps
The Posta sandstone figures are located at a height of 30 meters on the east side of the cathedral and were covered with mosses, lichens and algae and so-called black crusts. In a first step, the cleaning experts removed the biogenic growth using hot water high-pressure cleaners in the gentle steam stage at 95 °C and a reduced pressure of maximum 0.5 - 1 bar.
The incrustations were thinned out in the second work step. The low-pressure particle blasting method was used: from a distance of 10 to 20 cm and at a surface pressure of 0.5 to 2 bar, the specialists, equipped with respirators and protective suits, gently removed the layers of dirt with an aluminum silicate blasting agent. This technique was also the method of choice for cleaning the southwest tower. It is similar in principle to the familiar sandblasting method, except that the low-pressure particle blasting process is much gentler. Following the cleaning, the restorer of a commissioned stonemasonry company will carry out consolidation and supplementary measures on the figures with the financial support of the Cathedral Construction Association.
In a first step, the cleaning experts removed the biogenic growth using hot water high-pressure cleaners in the gentle steam stage at 95 °C and a reduced pressure of maximum 0.5 - 1 bar.
The figure of Moses was cleaned using low-pressure particle blasting: From a distance of 10 to 20 cm and with a surface pressure of 0.5 to 2 bar, the specialists, equipped with respirators and protective suits, gently removed the layers of dirt with an aluminum silicate blasting agent.
The cleaning effect is clearly visible.
Condition of the cathedral
Various damages to the cathedral facade have been known since 2018. Since then, the comprehensive restoration of the four corner towers above the main cornice has been underway. The damage to the columns, pilasters, capitals, decorative elements and figures made of sandstone was caused by soot, rain and exhaust fumes, among other things. Penetrating rainwater has additionally damaged the stone substance due to defective or missing joints. Since the beginning of the work, about 20 percent of the necessary restoration measures have been completed.
All facts at a glance
Kind of dirt: Biological fouling, soot, rubber abrasion and dust
Cleaning method: Steam stage of the hot water high pressure cleaner, low pressure particle blasting.
Execution: August 2022