Today stonemasons are closely cooperating with conservationists. They utilise their knowledge of stone processing and carry out not only simple repair work, but they also restore complex architectural details.
The repair process starts with choosing the right material for dutchman repair.
It is preferable that the stone used for the repair comes from the same deposit as the original stone unit. However, this is not always possible because repairs often concern buildings that were constructed centuries ago. The deposit might have been exhausted and the quarry closed or used for different purposes. Furthermore, it is not always possible to obtain information about the origin of the material. In any case, the stone chosen for repair should be as close to the original as possible in terms of colour, texture and grain size.
We start the repair by measuring the crack and preparing the dutchman block. After that we prepare the parent stone by levelling off the damaged portion of the parent stone. The dutchman unit is sized to minimize the joint between the dutchman and the parent stone and then installed in the prepared profile. We can use anchorage to ensure the dutchman does not dislodge of shift out of alignment. Once set, the dutchman should protrude slightly and the final grinding should take place after the installation has taken place to achieve a better blending of colours with the parent stone.
Some restorers choose to keep the original colour of the dutchman. This approach has its supporters, but also opponents who question the aesthetics of such implementation. Fortunately, it is always the restorer who has the final say in the matter.
The purpose of dutchman repair is to restore damaged elements, prevent further deterioration and improve the appearance of the building. However, there is one more aspect to take into consideration before we start the repair work. We are talking about traces of historical events, such as bullet holes, trace of sabre sharpening on sandstone, or small holes, so-called penitents. I personally believe these marks of time should be preserved, because they represent a part of the history of the building.
Source: Kurier kamieniarski
Author: Dariusz Dembińska | Published: 02 July 2019