Cleaning a Flagstone Walkway

There are two general types of flagstone walkways: indoor and outdoor. Usually an indoor flagstone entry or walkway will have sealant and wax on it to make it barefoot friendly. To clean this type of flagstone you should be able to simply wet it down and mop it with warm water and all-purpose cleaner. For scuffs and marks try using Bon Ami or Comet, and a little of your own scrubbing action. If, after cleaning, you detect a slight film or residue on the surface of the flagstone, you can wipe it down with a rag and a half vinegar half water mixture.

Unlike indoor flagstone, outdoor flagstone is not usually sealed and waxed. Thus, like any other rock outside, it is susceptible to dirt and erosion.

For regular dirt and mud stains get a hose and a pressurized nozzle and spray down the area until the dirt has been washed away. For more stubborn stains you can also use dish soap or dishwashing detergent. When you are spraying, be sure to use a gentle setting so you don't add to the erosion of the rock.

If your flagstone has natural stains caused by leaves or trees you can treat it with organic stain removers. These stain removers work to break down the carbon-based dyes that are causing the stains. Before obtaining this type of cleaner, be sure that you know that the stain on your flagstone is caused by organic materials. Organic stain removers will not work against non-organic stains. Also, before using the stain remover, you may want to test it on a small, inconspicuous patch of flagstone, just to be sure that the product will not discolor the stone.

If you have stains that will not come out with washing, stain treatment, or natural bleaching from the sun, your final resort may be to use muriatic acid. This substance does not fight stains, it eats away at whatever it is applied to. Using muriatic acid will remove the top layer of your flagstone, flaking away the stained portions. To do this process, first protect yourself with heavy clothes, gloves, and goggles. Using the proper dilution guidelines on the label, apply the acid to the stone you wish to clean. Allow it to sit for a few minutes, and then scrub or power wash it off. Be sure to soak the whole area with enough water to dilute the acid. Complete the job by applying masonry sealant to the newly exposed layer of stone. The sealant will stop the stone from eroding any further and should protect it from getting too dirty again.