Copper is used in the bottom of pans because it heats quickly and evenly distributes the heat across its surface. Copper-bottom pans can become burned if they are allowed to sit too long on a burner, left on a burner while empty or catch on fire. Burnt copper loses its ability to heat evenly and may leave your food with a burnt taste. But instead of throwing the burnt pan out, try fixing it with simple cleaning methods.
Remove any burnt food from the inside bottom of the pan. Add two to three drops of liquid dish soap to the bottom of the pan. Fill the pan with hot water until the layer of food is covered. Mix in 2 tablespoons of baking soda. Allow the pan to soak for at least one hour.
Try scrubbing the burnt food from the pan with a non-abrasive scrubbing pad. Leave the pan to soak overnight if the food is still firmly stuck to the pan. Scrub the food from the pan and rinse in hot water. Dry the pan with a cloth.
Turn the pan right side down to expose the burned bottom. Spread a layer of tomato ketchup evenly over the burnt copper bottom. Let the ketchup sit on the pan for one hour to allow the acids to eat away at the burned spots. Wash the ketchup off with hot water while rubbing the surface of the pan's bottom with a non-abrasive scrubber. Dry with a soft cloth.
Fill a microwave safe bowl with 1/4 to 1/2 cup vinegar. Heat the vinegar in a microwave for 30 seconds on medium-high heat. Mix 1/2 cup table salt and 1/2 cup white flour in a second bowl while the vinegar is warming up. Add the vinegar to the dry mix until a thick past forms. Spread the paste over the copper bottom of the pan. Rub the paste into the pan's bottom with a cloth. Let the paste sit on the pan until it dries. Wipe the excess paste off with a cloth and rinse the pan's bottom in hot water.
Cut a lemon in half with a knife. Dip the cut surface of one lemon half in the remaining table salt. Rub the salted lemon over any remaining burnt or tarnished spots on the pan's copper bottom until the stains disappear. Rinse the pan in hot water and dry with a cloth.