Harl (plaster)

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Harl-plastered facade of Craigievar Castle
Facades in Port Charlotte, mostly plastered with Harl

Harl is a special rough plaster traditionally used as exterior plaster in the western areas of Scotland and Northern England . It has a very high weather resistance and is well adapted to the humid climatic conditions in these regions. It is mostly applied to stand-alone buildings or exposed facade surfaces. Due to its large surface area, facades plastered with Harl have high evaporation rates and thus avoid cracking due to moisture.

Harl is a clay plaster with small pebbles. To plaster a surface with Harl, a layer of clay is first applied to the masonry. Using a special device, the Harl is thrown onto this layer so that the stones sink a little into the clay surface and a connection is established. Harl is usually applied in a layer up to 2.5 cm thick. The pebbles create a rough surface, which not only has a decorative effect, but also reduces the speed of rain running down the facade and thus reduces weathering. It also allows irregularities in stone walls to be leveled out. Harl can be colored with pigments such as lime before use. In order to harmonize the look with decorative elements made of red sandstone , a light pink color is created by adding sandstone dust, while brownish colors are achieved by adding liquid manure .

In the Hebrides in particular , Harl was often used as an exterior plaster. For example, all of the 19th century buildings along the main street of Port Charlotte are plastered with Harl. The Harling technique was also used on the facades of numerous historic castles, manors and country houses.

Individual evidence

  1. H. Conway, R. Roenisch, C. Hazel: Understanding Architecture: An Introduction to Architecture and Architectural Theory , Routledge, 2005, p 120. ISBN 0-415-32058-5
  2. ^ R. Hunt, M. Suhr: Old House Handbook: A Practical Guide to Care and Repair , Frances Lincoln, 2008, p. 157. ISBN 0-711-22772-1
  3. ^ S. Reid, G. Turner: Castles and Tower Houses of the Scottish Clans 1450-1650 , Osprey Publishing, 2006, pp. 22-23. ISBN 1-841-76962-2 .