Could you correct my report ? Clean coins with vinegar what you need : Three dull 10 won (Korean currency), vinegar, salt, cup, paper towel Step1 Pour the vinegar into a cup and add the salt. Step 2 Stir it up Step3 Put 3 coins into the cup and count to 10 slowly. Step 4 Take out the coins and rinse them in water. Step 5 Rub them with a paper towel. How does it work? The acid in the vinegar reacts with salt to remove copper oxide which was making 10 won dull. That’s why you could make the coins shiny.