Harling (wall finish)

After a wall is complete and has been pointed and allowed to cure then a base of lime render is applied to the bare stone.

While this render is still wet a specially shaped trowel is used to throw the pebbles onto the lime surface, which are then lightly pressed into it.

Cement-based render is very stiff and prone to crack or detach from the wall when subjected to stress induced by expansion due to solar radiation and moisture.

Water entering through fine cracks in the surface does not easily diffuse and can penetrate into the softer stone, thus causing the deterioration which harling aims to prevent.

[11] The lime used with sand to "pergyn" two round turrets and vaulted entranceways or "transes" at Holyrood Palace in 1532 came from Cousland and Gilmerton.