Bath Stone, a beautiful oolitic limestone, is a defining feature of the Georgian architecture in the city of Bath and evident in many other areas of Wiltshire and Somerset. It’s beautiful to behold, but being porous it is susceptible to becoming soiled, stained and corroded, losing its looks over the years as a dirty crust builds up to mask the original pale creamy-buff hue of the stone beneath.
Pollutants in the atmosphere and biological growth like algae and moss not only spoil the aesthetic beauty of Bath Stone over time, but can also lead to physical damage. For example, sulphur dioxide in the air reacts with the stone to form calcium sulphate crystals, absorbing more pollution and eventually leading to erosion and decay.
Heavy soiling can clog the pores in the stone, trapping moisture, which can cause corrosion of fixings and iron cramps and freezing in winter, resulting in the surface shattering.
To prevent the worst and preserve the stone for posterity it is therefore necessary to keep Bath Stone facades and features clean – but that doesn’t mean taking a scrubbing brush to it! It requires professional knowledgeable stone masons with gentle techniques to tackle the cleaning of Bath Stone, or you could do more harm than good.
We’re proud to say that we at Sandridge Stone Ltd have earned a reputation for leading the field in the careful cleaning of Bath Stone in the local area, in the heritage city of Bath itself and across Somerset, Wiltshire, including Bradford-on-Avon and Melksham.
Our Heritage Skills qualified stone conservators use a range of techniques to gently but effectively clean Bath stone, all of which we have perfected with experience. We always adopt an approach which is sympathetic to the historic fabric of the building to ensure that the result will be beneficial to the long-term health of the stonework as well as to the short aesthetics.
Our main method, used when appropriate, is the superheated water system known as ThermaTech: a high-performance piece of portable machinery which uses hot water under a little pressure. This system has proved particularly reliable and safe for use in masonry conservation and cleaning.
Other Bath stone cleaning methods include:
Before any cleaning can take place, we carefully survey and assess the stonework so we can plan exactly what methods should be used where on the building to achieve safe, effective results. “Patch tests” are often carried out to ensure that our cleaning techniques will achieve the best outcome, before we go ahead.
Many of the buildings we clean are Grade I & II listed properties and we are well versed in providing information about the intended works to local authority listed building officers in support of planning applications.
There’s no recommended frequency for the cleaning of Bath Stone structures because their condition, level and type of soiling depends largely on the location and environment. Overcleaning is best avoided because it could open the stone’s pores to faster re-soiling.
Stone cleaning is often undertaken along with any repairs that may be required as part of a conservation programme, and regular inspections and monitoring will identify when a clean becomes necessary to prevent damage and maintain the building’s health and appearance.
If you own or manage a beautiful Bath Stone building that you feel is in need of a face-lift, give us a call and we’ll be happy to cast our expert eyes across it. We give free advice, and quotations for any work that may need doing.
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