Give old stone its youthful appearance again

fotografie historického podloubí v historické části města kolem kterého jdou 2 dámy středního věku

Even old stone can look as new. It is not that difficult. It makes much more sense to preserve old natural stone and to return it back to its old glory, than to waste it. Natural materials wear down with time, but even stone in any of its forms can be renovated. In the same way you can sand and newly paint natural wood for example.

All the kinds of stone were created during complicated natural processes. They gave it its character, look, and nature. Stone has its place in modern architecture as well as only in historical. Stone is long-lasting, that is why it has become the ideal material for building– its price corresponds to it. It is also durable, processable, tough, and it has a unique appearance. You could also say that each piece of stone is an utter original of unrepeatable shape, texture, and colour.

Natural stone can be used in interiors and exteriors of buildings, as well as in gardens and parks, or in public spaces. Stone cladding, paving, stone plinths and stone staircases look very good as well. No matter how you use stone, time will always leave its mark on it. That is why it is necessary to revive it after some time. However, this is not an activity that you should do on your own. What does the renovation of stone include?

How can stone be cleaned?

There are several ways in which natural stone can be cleaned, renovated, or even restored. Mechanical, chemical, or combination of these methods can be used. But there is another activity at the beginning of the process. First, you need to assess the condition of stone and the way it is used. Only then you can propose the form of renovation. Whether it is an exterior or interior renovation, what kind of stone it is, and if it was renovated in the past, is also very important.

Apart from mechanical and chemical methods of stone renovation, there are also so called dry and wet methods. Dry method is mechanical cleaning of stone. Approximately 1 mm layer of stone is removed while the surface of stone is roughened and cleaned. The more the layer of stone is weathered the bigger the wastage will be. Dry mechanical cleaning is done with the help of a pneumatic pistol, no abrasives and chemical detergents are used. It is appropriate especially for the interiors because the wastage comes only from the stone and released soiling. This method is also called bush-hammering (the surface of stone is mechanically struck). The result of this method is the same as with abrasive jetting.

Wet method is actually the sandblasting of the surface with high pressurized tool using abrasive silica sand and water. It is mostly used on outdoor stone elements and surfaces. Used abrasives and soiled water are released into the surrounding space, but there is no dust, which would be undesirable in the outdoors. On the other hand, in the interiors, soiled water could soak in the walls and the abrasive would end up practically everywhere.

Chemical cleaning, on the other hand, is appropriate only for undamaged surfaces, meaning surfaces that have the upper layer of its surface only soiled (not damaged). Chemical cleaning has two phases. In the first phase, the soiling of the surface is removed. In the second, you must neutralize the remains of the cleaner. The cleaner must necessarily be removed, so that it could not cause further destruction of the stone surface. As soon as the treated stone is dry, you perform hydrophobization (lowering of water attraction of the surface).