Flagstone is a decorative material to build your patio with or add a path to your home. Unlike indoor flagstone, the flagstone you use outdoors usually does not have a sealant. Because of this, your outdoor flagstone requires cleaning on a regular basis to prevent stains from setting. One stain that is common to flagstone and virtually unpreventable is bird poop. Often bird poop is combined with the berries the bird has eaten. Cleaning bird poop from flagstone before it has a chance to set in will prevent permanent staining.
Scrape off as much of the bird poop as possible with a plastic putty knife. Using a plastic putty knife does not scrape the flagstone surface.
Rinse the bird poop area on the flagstone with water to remove as much residual as possible. Mix a strong solution of washing soda and warm water in a bucket according to the directions on the soda package.
Dip a horsehair bristle brush into the solution and scrub the bird poop area with the brush.
Rinse the area thoroughly with a garden hose if possible. A garden hose with a sprayer allows you to apply pressured water to the bird poop area for complete removal.
If the bird poop stain has set into the flagstone, it might be necessary to use muriatic acid instead of washing soda.
Wear rubber kitchen cleaning gloves when cleaning bird poop and using harsh chemicals.