Apologies in advance for the quality of the photographs below, they were taken in the sitting room of an old 18th century cottage near Weymouth and the lighting was not its best, although I’m sure fans of the TV series Poldark would have loved it. The floor was 20m2 Portland Limestone flags which hopefully you can see was not looking its best and I suspect it had been some time before it had been given a thorough deep clean as it was now grey, grimy and generally tired.
This type of floor is quite common in houses before the 19th century and usually consisted of the beaten earth being covered with thick slabs of stone. When left over time it becomes grey and dry and flaky but when cleaned and sealed it turns almost as black as its near relative Purbeck marble and even shines when polished.
Cleaning Portland Limestone Flagstones
To get the floor clean I applied a medium dilution of Tile Doctor Pro-Clean which was left to soak into the floor for about ten minutes before being scrubbed in with a black scrubbing pad fitted to a Numatic buffing machine. I also ran a stiff narrow brush along the grout lines to get them clean.
The floor was rinsed down with water to dilute the now soiled cleaning solution and this was extracted using a wet vacuum. To add a little polish to the Limestone I ran over the stone using a fine diamond encrusted burnishing pad, the floor was still a little damp which helped lubricate the process. Once done the floor was given another rinse again using the wet vacuum to remove as much liquids as possible before leaving it to dry off fully overnight.
Sealing Limestone Floor Tiles
The next day I sealed the floor using two coats of Tile Doctor Colour Grow sealer which impregnates the pores of the stone to provide lasting protection. The floor now looks clean and bright and a lot closer to the near-black colour that it should be.
Source: Professional Tile, Stone and Grout maintenance service in Dorset