Schäden, die durch Imprägnierungsmittel verursacht werden - Ursachen und Gegenmassnahmen / Damage caused by Water Repellent Agents - Reasons and Counter-measures

In several discussions, but also on the sites, the following thesis can often be heard: "Hydrophobic agents cause damage on stone surfaces!" or "Water repellent properties vanish in a few years!" In spite of this we know that great efforts have been done in research and development of water repellent agents in the past 20 years. So we can choose today between a great amount of different products for nearly every type of application. A lot of damage still occurs. This paper describes the typical destructions from some examples out of 15 years of practical experience and gives an explanation for the origin of the damage. In almost every case there are 2 main factors responsible for the damage: Caused by the lack of essential preliminary examinations on the building, there is no sufficient knowledge about facts and dates concerning the building materials. On the other side application is an important factor, and there is only a very small progress to be seen during the past decades. Mistakes in application lead in a very short time to a great amount of damage - and this may be the main reason for the general "bad reputation" of water repellent agents. Last not least, the architects, civil engineers and the building owners carry a certain responsibility too, especially for the lack of information on these complex topics and the lack of control during application.