While you don't want to get rid of that authentic patina, you have to remove caked-on mortar, dirt, mold or mildew, and general staining. Thankfully, renewing old bricks is easier than you think.
Mohd Khairi said that upon investigation, the object was identified as an old, rusty mortar bomb. The bomb disposal process was carried out on the same day at the site of the discovery.