Painting lime by Mirene Pastrena

Lime is one of the finest materials to be used by Man for millennia. The oldest remains are the frescoes in the city of Catal Hüyük which date back to six thousand years before our era. The Romans picked up on the experience of Assyrian palaces, Egyptian stuccoes and the beautiful Greek plasterwork and exploited its qualities to its utmost as a building material. The exclusive use of cement in restoration is being substituted by lime by experts who are upholding its use in the rehabilitation of our heritage. Putty lime is used as a basis for making mortars that are applied as plastering or stucco. The most important characteristic of lime mortar is that once in place on the work (as pointing, gesso or stucco), it will continue hardening through recarbonation until it becomes a stone-like crust just a few millimetres thick which grows increasingly resistant. During this recarbonation process of the lime, the slaked lime, in contact with the carbonic gas in the air, is transformed into calcium carbonate (CaCO3); i.e. it becomes the stone with which the cycle began once again. With a controlled slaking process, lime will not change in volume when it hardens through air carbonation. The perfect integrity of joints, the absence of shrinkage and the property of hardening over time makes lime mortar an excellent thermal and acoustic insulator that prevents water penetration and does not generate smoke in the event of fire. With regard to finishes, the possibilities are endless. Given that it is a very malleable material, before it hardens it can be worked with all kinds of tools, achieving the appearance of roughened ashlars, polished stone, etc. and allows the inclusion of a wide range of colours and even different reliefs in order to imitate a simple brick structure, gleaming marble or providing a canvas for the free brushwork of the great fresco artists.