Bring enough water to a boil in a large stockpot to completely submerge the copper item. Add 1 tablespoon baking soda for every quart of water.
Submerge the copper item in the baking soda solution. If the item is too large to submerge, use tongs to dip one portion of the item at a time. Remove the item when lacquer starts to peel off and float to the top.
Scrub the item with a nylon scrubber and soapy water to remove the loosened lacquer.
Polish the item with commercial copper cleaner and a soft sponge.