Sandstone is used extensively as a building material throughout Scotland. In fact, it has been used since prehistoric times. Why? Most types of sandstone are reasonably resistant to weathering, easy to fashion and cut. It is an attractive material, giving a light and airy aesthetic. This is evident in locations such as Edinburgh's New Town World Heritage Site and Glasgow's West end, with its striking red sandstone.
What of cleaning and restoring sandstone?
We are all familiar with older buildings with a green tinge, or perhaps a build up of soot and carbon, dulling that otherwise light, clean finish.
High Pressure water cleaning will damage sandstone. No question. The high pressure water is readily absorbed, and causes the outer layers of the stone to quickly crumble. This opens up surface of the stonework, causing a pitted, spongy texture. Due to the new extended surface area, this quickly becomes re fouled. Further cleaning over time compounds the problem. Additionally, the softer lime mortar traditionally used with Limestone building is also damaged by high pressure. This can crumble prematurely, unnecessarily exposing joints to weather and frost.
So how can Sandstone be properly cleaned and restored? Low pressure, steam cleaning. Low pressure does not penetrate the soft stonework or tear away at the outer layer of stone. Steam evaporates, preventing it being deeply absorbed by the stone. It removes algae and moss, while the high temperatures kill spores, help preventing quick regrowth. It can be used to provide a range of finishes, from completely clean, to a more sympathetic, age appropriate clean, leaving behind deeper set lichens and weathering. Architects often refer to this type of cleaning by the brand name DOFF Cleaning. DOFF cleaning uses low pressure and high temperatures to gently clean softer stone works and its mortar. Achieving a deep clean, without cutting deep in to the stone. Stone Clean Scotland uses this technology along with a comprehensive knowledge of sympathetic cleaning and problem solving to restore sandstone to a beautiful finish. Find out more by clicking below.
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