In 1968/69, the thermal products were developed together with the Graz University of Technology and were launched onto the market in 1970 (“ThermoMörtel, ThermoPutz, ThermoSchlitz”). All the products were made from the volcanic rock perlite. In this process, perlite is expanded at higher temperatures and its volume increased by factors of 15 to 20 while, at the same time, intensifying its thermal insulation properties. In the late 70s, polystyrol was added to the plasters as an alternative to perlite, and a plaster called ThermoExtra Putz was born and introduced to the market. This, again, meant an improvement in thermal insulation behaviour, but on the other hand some of the pressure resistance was lost. As the façade insulating slabs appeared, the heyday of insulation plasters and mortars suddenly came to an end.
