Part cleaning is only the first important step to proper finishing technique; pretreatment is the critical step for paint adhesion & corrosion resistance. The cleaning process removes oils, soils & other contaminants from the surface, providing a fresh substrate to deposit a pretreatment foundation for paint to adhere to.
Electrocoat (e-coat) is an immersion (dipping) process very similar to plating except we are depositing organic finishes, not metal.
Liquid coating refers to the most traditional finishing application of wet paint. There are still many uses for wet spray: fancy finish colors unable to be reach via powder coating (like for autobody), specific texture patterns unique to paint, soft suede finishes, wood coatings, plastic coatings, and other non-bakable material finishes.