Mark asked: What is the best way to clean flagstone? I have a light colored flagstone patio and walkways which get very dirty from the elements and mold (shaded areas). I have a power washer and have used strictly water, but it needs something better.
Table of Contents:
Flagstone provides a beautiful, natural-looking landscape and requires special care to protect it from damage. Here are some steps to get your flagstone looking new again and removing serious dirt and stains.
You Will Need:
- Muriatic acid
- Bleach
- Water
- Bucket
- Plastic bristled brush or broom
- Flagstone sealer (optional)
Steps to Clean the Flagstone:
- Mix 1 quarts of muriatic acid with 2 gallons of water in a bucket.
- Use the brush to apply the mixture to the stone and scrub well.
- Rinse COMPLETELY with water. Allow the acid to sit on the surface will result in damage.
- Next, mix some bleach in with a bucket full of water. The amount of bleach needed will depend on the type of flagstone and the level of dirt build-up.
- Apply the mixture with the brush and scrub again until the surface is clean.
- Rinse again with clean water, ensuring that all of the bleach is removed.
- Allow the area to dry completely, at least 24 hours or more.
- Apply a good quality sealer to the surface following the manufacturer’s guidelines. This will protect the surface and make future cleanings much easier.
Additional Tips and Ideas
- For general cleanings, a power washer with plain water is best.
- Avoid using any acidic or scouring cleansers as they can damage the surface of the stone.
- To get rid of mold and mildew, apply boiling water to the surface and scrub with a plastic brush.
I think it might be wise to mention the fact that muriatic acid is an extremely dangerous chemical, and that anyone using it might want to have the necessary equipment needed (rubber boots, heavy duty rubber gloves, vinyl-coated cover-alls, full-face protection with a respirator, etc.). Your article gives absolutely no indication of this.
In addition to the safety precautions, mixing chlorine bleach with an acid will result in the release of chlorine gases that are toxic, resulting in burning of the lungs in high enough concentrations. Be very careful to wash the acid away thoroughly before using the bleach solution.
Good luck!