Moisture and salt transport in three-layer plaster/substrate systems

We have investigated whether a plaster which has two plaster layers with different pore sizes can act as a salt accumulating plaster system, in which salt crystallizes in the base layer of the plaster and not in the substrate or at the external surface. We used two substrates; fired-clay brick and Bentheim sandstone. On the substrate we applied...

Black weathering of Bentheim and Obernkirchen sandstone

Black weathering of sandstone in monuments is widespread. Some obiects owe their name to it, like the Porta Nigra in Triet (Germany). Other than the black gypsum crusts common on limestone, the black weathering layer on sandstone is rather thin and well adhe¡ent. Formation of such layers on Bentheim and Obernkirchen sandstone, both widely used...