The normal coin is not clad but an alloy of copper and nickel. If you'll dip or put it in acid, you'll never end up with a copper coin. The acid will automatically attack copper, silver, and nickel that would result to corrosion. Gold and platinum meanwhile can resist acid attacks. Therefore, even if the coin is clad nickel or copper-nickel, you may never strip down the coin because acid will automatically penetrate both the layers resulting to uneven surfaced coin.Thank you for viewing.