After Step #1 (two days in heated caustic chemical at over 200 degrees) every part is fully cleaned with very high pressure fresh water.

Very critical step of the cleaning process is using the high pressure fresh water to remove material and clean seams.

The images below show some of the cleaning of a car body after two days in the hot tank. As you can see the heated chemical dip softens the material allowing the use of fresh water high pressure washing to remove it. Use of only water means zero damage to the sheet metal.