

The clear coats applied to the plastic components like the bumpers and wing mirrors however are 2K systems since they can normally only accept temperatures up to about 90 ☌. Car manufacturer ( OEM) clear coats applied to the metal bodies of cars are normally 1K systems since they can be heated to around 140 ☌ to effect cure. One part and two part formulations are often referred to as "1K" and "2K" respectively. Clearcoat can be either solvent or water-borne. For this reason, clearcoat must be durable enough to resist abrasion and chemically stable enough to withstand UV light. Usually sprayed on top of a colored basecoat, clearcoat is a glossy and transparent coating that forms the final interface with the environment. Pearlescent paints can be two stage in nature (pearl base color + clear) or 3 stage in nature (basecoat + pearl mid-coat + clear-coat). Pearl pigments impart a colored sparkle to the finish which works to create depth of color.

Solid paints have no sparkle effects except the color.Base coat used in automotive applications is commonly divided into three categories: solid, metallic, and pearlescent pigments. This coat contains the visual properties of color and effects, and is usually the one referred to as the paint. The base coat is applied after the primer coat. In E-Coat, also called CED paint, use is approximately 99.9% and provides superior salt spray resistance compared to other painting processes.

The body works as a cathode and the paint as an anode sticking on the body surface. The body is dipped into the Electro-Coat Paint Operation (ELPO/E-Coat), then a high voltage is applied. A phosphate coat is necessary to protect the body against corrosion effects and prepares the surface for the E-Coat. Without proper pretreatment, premature failure of the finish system can almost be guaranteed. High-pressure water spray jets are directed to the body. Water-based acrylic polyurethane enamels are now almost universally used as the basecoat with a clearcoat. Enamel paint is better for the environment and replaced lacquer paint in the late 20th century. Up to 85% of Lacquer paint can evaporate into the air, polluting the atmosphere. Environmental laws have prohibited this, which has resulted in a move to water-based paints. Until several decades ago lead, chromium, and other heavy metals were used in automotive paint. Nowadays, two-component (catalyzed) paint is usually applied by robotic arms and cures in just a few hours either at room temperature or in heated booths. As mass production of cars made the process untenable, paint began to be dried in ovens. In the early days of the automobile industry, paint was applied manually and dried for weeks at room temperature because it was a single component paint that dried by solvent evaporation.
