Which cleaning method carries a risk of mortar smear or acid burn if not used properly?

• A. Sandblasting
• B. Pressure washing
• C. Chemical cleaners
• D. Brush and water

Answer: (C)

When cleaning masonry, the danger comes from cleaners that contain acids or strong caustics. These chemical cleaners can burn skin or eyes if they spill or are mishandled, and they can react with the mortar in the wall. If used improperly—undiluted, left on too long, or not thoroughly rinsed and neutralized—they can dissolve or weaken the mortar, creating a mortar smear or etching on the surface. To avoid these issues, follow the product label, wear protective gear, test a small area first, use the correct dilution, and rinse completely. The other methods rely on physical action rather than chemical reactions, so they don’t carry the same risk of chemical burn or mortar dissolution when used correctly.