How to Remove Mortar Residue Off of Flagstone

Mortar residue can detract from the appearance of your completed flagstone surface. You can remove mortar that may have been dropped onto flagstone and missed as you were laying it or grouting it with hand tools and an acid wash. While muriatic acid is an effective option, there are acid washes designed for use on flagstone surfaces that are more environmentally safe. Use these washes to keep your yard and the environment protected. Wiping up mortar while it is still wet will help prevent most of the need for later removal, but even dried-on mortar can be effectively removed.

Things You'll Need

• Trowel
• Wire brush
• Mortar remover acid wash
• Water hose

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Instructions

1. • 1

     Scrape off any larger areas of mortar off from the surface of flagstone with the edge of a trowel.

   • 2

     Brush the mortar with a wire brush to remove any remaining mortar from the surface until you are left with just a thin film of mortar that cannot be removed.

   • 3

     Apply the acid wash to the surface of the flagstone. Allow it to sit on the surface until the mortar residue appears to be loosened.

   • 4

     Brush the residue off with a wire brush while the wash is still on the flagstone. Rinse the residue and acid wash off with a water hose until the flagstone surface is completely clean.