Bricks are very porous, which is great for building, where mortar and cement can seep into the pores of the bricks, creating a tougher bond. However, the porous nature of bricks can be a downfall when an unwanted substance falls onto the bricks. One of the hardest materials to remove from the surface of bricks is glue. Glue can be removed from bricks with the use of adhesive removers or muriatic acid. The type of removal method used depends on the type of glue that is stuck to the surface of the bricks.
Use this removal method with solvent glues, wood glues and all-purpose glues. Pour a citrus acid-based or soy-based adhesive remover over the surface of the brick. Check the product label to see how long the remover should sit on the glue. The sitting time for adhesive removers is typically between two and four hours.
Scrape away the glue with a putty knife. Scrape away remaining glue with a stiff brush.
Rinse the area with water and a detergent solution to remove any glue residue.
Use this removal method for hard adhesive glues, such as cement glues, plaster of Paris and mortar. Chip away as much of the glue as possible with the chisel and putty knife. Dampen the surface of the bricks with water. This helps the acid absorb better into the pores of the bricks without damaging the bricks themselves.
Mix 1 part muriatic acid with 3 parts water. Pour the solution over the bricks. Allow the mixture to sit for about 20 minutes. Scrub the area with a stiff bristle brush to remove loosened glue particles.
Rinse the bricks with water to dilute the acid to prevent the bricks from getting eaten completely. It may be necessary to seal the bricks after treating with an acid solution to protect them from further weathering. Bricks can become weaker after washing with an acid solution.