This was an unusual request to clean a large Limestone wall used to mount a sign at a Reading Business Park that had been installed approximately 8 to 10 years prior and never cleaned. The old sign had been removed from the stone which had exposed the unprotected areas of stone leaving a shadow. Pollutants, carbon soils, road dirt and weathering had discoloured the Limestone and the client was unable to get it satisfactorily clean. You can see from the photo below how obviously dirty the stone had become.
Deep Cleaning a Limestone Wall
To get the Limestone cleaned I applied a liberal 50:50 dilution of Tile Doctor Pro-Clean with a roller brush and allowed it to dwell for on the stone for around twenty minutes.
The chemicals got to work on the dirt whilst I set up our truck mounted medium pressure hot water clean and capture system which uses a twin rotary jet system to fire hot water at 90 degrees at 1200psi onto the stone in a circular spinning motion. It’s a great tool that immediately vacuums the waste water away to a separate tank in the van. This mess free clean and capture system is self-contained and doesn’t require the disposal of hot water or dirty water on site either. Using the tool I was able to blast away the soils and pollutants from the stone and then left it to dry.
Sealing the Limestone Wall
When I returned I checked the stone was dry, fortunately it hadn’t rained and the sun and wind had dried it out well. To seal the Limestone I used Tile Doctor Colour Grow which is an impregnating sealer that occupies the pores in the stone to prevent contaminates discolouring it, additionally it’s suitable for internal and external applications and has the added effect of enhancing the natural colour in the stone. Unfortunately I didn’t have time to take a final photograph once it was sealed due to a rather irritating traffic warden.
Source: Commercial Stone and Tile Cleaning in Berkshire