cleaning-guide-for-masonry

Not all bricks are suitable for acid cleaning. In particular, yellow, blue-dampened and manganese-containing bricks may be sensitive to acid-based cleaning agents.

Acid cleaning of brickwork may cause efflorescence and discolouration of both bricks and mortar joints. This is especially true for yellow, blue-dampened and manganese-containing bricks.

Bricks may become discoloured, develop efflorescence or, in the worst case, suffer surface spalling if cleaned with acid.

When masonry is cleaned with hydrochloric acid, the acid also reacts with the lime in the mortar and breaks it down. This reduces the service life of the joints and may create degradation products that absorb moisture (hygroscopic), causing the masonry to appear damp. If cement-based mortar is used, acid cleaning is generally ineffective and may result in mortar slurry being deposited on the brick surfaces.

Therefore, masonry should be laid clean to avoid the need for acid cleaning. Masonry cleaned only with water may retain small amounts of mortar residue. The expected final appearance of the masonry should therefore be agreed with the client before completion.

1. Check whether the supplied bricks are suitable for acid cleaning.

2. Keep the masonry clean during construction and compact the joints in accordance with the mortar manufacturer’s recommendations.

3. Remove mortar residues once the joints are sufficiently dry using a dry coarse scouring sponge. The sponge must remain clean and dry throughout the process.

Cleaning masonry without acid treatment

4. As a final treatment, the masonry may be cleaned with water. Use a sponge float and a bucket fitted with rollers. Roll the float over the rollers until the sponge is thoroughly wrung out. Always use clean water and change it frequently. Take care not to drag mortar slurry from the joints onto the brick surfaces.

Cleaning masonry with acid treatment

5. If acid cleaning is required, use a ready-mixed masonry acid diluted 1:20. Apply the solution using a sponge float and a bucket fitted with rollers. Roll the float over the rollers until the sponge is thoroughly wrung out. Clean the masonry diagonally in a single pass. Repeated cleaning of the same area may cause acid build-up and result in damage. Always use clean masonry acid and replace it frequently. Take care not to drag mortar slurry from the joints onto the brick surfaces.