Conventional cleaning methods can damage or degrade stone, accelerating erosion and decay. Softwashing both cleans and protects any stonework. Regular scheduled stone cleaning, using specific procedures and inspections, are recommended to keep high value or conservation stonework in prime condition.Before cleaning stone it is first vital to identify the type of stone it is. Natural stone is classified into two categories: siliceous stone or calcareous stone. Knowing the difference between these two is critical when defining the right cleaning process or selecting the appropriate blend of detergent.
Sandstone can erode easily, and high pressure washing can seriously harm fine details or even whole facades. Softwashing is safe for sandstone and cleans deeply.
Softwashing is a popular method for washing limestone in the US, and this service is now available in the UK too. It's gentle on stone and a very effective cleaning method. Many cleaning companies lack the experience to properly handle limestone. Power washing is not recommended, as it can blast away the surface and leave the subsurface open to erosion. Similarly many cleaning companies will rely on acid based agents, often off the shelf, no matter the condition of the stone or nature of soiling. Any cleaning agent with too high a pH level should not be used in limestone cleaning, as it seriously risks the integrity of the rock. Once damaged, Limestone is expensive to repair, and very expensive to replace too. For peace of mind, and the best results when cleaning limestone, it is best to rely on softwashing.