You don't have to use it straight. You can dilute it with water. I bought a cheap plastic tub and have four gallons of it to derust bigger parts. I only bought two gallons and added two gallons of water.

Neutralize it with baking soda water. Dipping the parts in EvapoRust after they are clean will keep them from flash rusting. Don't dip aluminum in the acid. It won't be there when you go to remove it.