Fill a commercial liquid tank with two parts of ammonia solution and three parts distilled water.
Spray the interior surface of the sulfuric acid tank.
Let the ammonia solution soak for two hours. The ammonia solution neutralizes the pH of the sulfuric acid.
Test the pH of the sulfuric acid tank. Wipe a piece of litmus paper on the side of the tank. Litmus paper turns blue when contacted with acid, and turns red when contacted with a base.
Repeat Step 2 and 3 until the litmus paper does not react.
Drain the excess solution from the sulfuric acid tank. Leave the tank open to dry.