WGL Stoneclean

The Steamacc Process A cost effective and eco-friendly alternative to traditional stone cleaning methods.

Scratching the surface

Leeds-based WGL Stoneclean Ltd, is one of the leading stone cleaning companies in the North of England. The company wanted to validate their novel cleaning method, known as the "Steamacc Process", which uses a super-heated steam that washes the acid used in the standard cleaning process from the stone. This significantly reduces the dilution of the acid within seconds, removing the small carbon deposits that cause staining in the masonry.

Business issue

WGL Stoneclean Ltd approached the Department of Civil Engineering at the University of Leeds to scientifically investigate the method in order to dispel scepticism amongst architects and conservationists, who believed that the new method would damage stonework faster than anticipated.

Academic expertise

Dr Leon Black was tasked to demonstrate that the cleaning process can remove the carbonaceous material (dirt) without damaging the underlying stone. Dr Black used his technical expertise in (Environmental) Scanning Electron Microscopy to find out the characterisation of stone pre-and post-cleaning to determine the extent of damage or material removal upon cleaning.


Three polished stone samples were prepared to be given to WGL Stoneclean Ltd for cleaning. Following this, Dr Black was able to analyse the samples by electron microscopy, a technique that enables high resolution, high magnification imaging of rough surfaces. Images are obtained at much higher resolution than is possible by optical microscopy making the results more informative and arresting when shown to the public.


Results from Dr Black's research concluded that the "Steamacc Process", was the least damaging, most cost effective and environmentally friendly (as lower acid concentrations and dwell times are used) available in the UK market.

Bernard Coleman, Director, WGL Stoneclean Ltd explained, "We continually refine our method of cleaning to solve various client requirements, creating bespoke cleaning methods. General blasting can result in the loss of layers, giving a bland appearance to buildings and masonry. By using the "Steamacc Process", we are able to leave the original colouring of the stonework. We were referred to a scheme that would enable us to work with Consulting Leeds [at the University of Leeds] to validate our new method of cleaning and work out precisely the degree of damage avoided by using the new process."

Major benefits

The research undertaken by Dr Black and his team resulted in major benefits for the company. It enabled WGL Stoneclean to convince sceptical clients of the merits of sand-free cleaning.  Bernard Coleman explained that the research exceeded his expectations:

"Following the success of the report we employed a graduate to promote the study, developed our website content and promoted this to our clients. In the past few years we have seen a notable increase in activity and sales. We have since developed a strong relationship with the University of Leeds and hope to work with them again on projects that are currently in development."

Dr Black explained, "I really enjoyed building the relationship with WGL Stoneclean Ltd. The work that I carried out related to my previous PhD research and I could see the impact of the work. I have since worked with WGL Stoneclean Ltd on several other small research projects and have regular contact on an informal basis with Bernard Coleman."

For further information contact Dr Leon Black

Visit the WGL Stoneclean website