You can clean your Aranmula Kannadi using brand-name brass cleaners such as Brasso or Day & Martins' metal polish.
Apply a few drops, then rub it with a cotton or velvet cloth smoothly on the surface in a vertical motion.
You can also substitute brand name polish for natural coconut oil if you want a natural solution for cleaning your Aranmula Kannadi and are not comfortable using chemicals in your home.