Wipe off any fresh mortar that has not set as soon as possible with water and a stiff-bristled or stainless steel brush. Mortar must cure for about seven days before acid cleaning can be done safely.
Remove all large pieces of excess mortar with a hammer and chisel. Be sure to wet the area to be cleaned thoroughly with water. Soak the bricks, but not to the point of leaving standing water on the surface and keeping them wet during the cleaning process.
Cover or protect any surrounding foliage or materials to prevent damage to plants, grass or other landscaping materials.
Put on protective clothing, mask and goggles. Hydrochloric acid is highly caustic and should only be used in areas with plenty of fresh air and good ventilation.
Mix one part hydrochloric acid to 20 parts of water for light colored brick and 1 part hydrochloric acid to 10 parts water for darker brick. Always add the acid to the water to prevent dangerous reactions and splattering. Higher concentrations than these can stain or damage brick.
Prepare a neutralizing solution of 50 grams of baking soda per one liter of water. Have it readily available during the cleaning. Pour it on acid if etching is occurring.
Test the solution on an inconspicuous area by leaving the solution on for no more than six minutes and rinsing thoroughly. Make sure the solution does not etch or stain the brick.
Apply the solution with a sprayer to a small area of pavers. Let the solution sit for three to six minutes before scrubbing with the brush until mortar is removed. Work one area at a time, making sure to not scrub the mortar joints.
Rinse the area with the baking soda solution to neutralize the acid. This is essential for light-colored brick. Rinse the area thoroughly with water and move on to your next area.
Things You Will Need
- Hydrochloric acid
- Baking soda
- Stiff-bristled nylon or stainless steel brush
- Hand cleaning is the recommended method with any dangerous chemical since it allows for more control.
- Pressure washing can be used as a substitute for scrubbing after the acid solution has been applied. Do not use over 1000 psi (pounds per square inch) of pressure or hold the nozzle too close--you could damage the surface. Run a test in an inconspicuous area first and follow the same rinsing procedure.