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5 min read

Car Paint Layers and Types of Paint Defects

Published on
April 10, 2024
front view of a red hood of a car
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Paint correction is a common practice in the detailing world, but what exactly does the paint being corrected consist of? What is automotive paint made of? How do paint correction techniques fix paint? These answers are vital to understanding your car's paint, so you can give it the absolute best.

What goes into automotive paint?

Typically a chemical or water based solvent is used to distribute base coat pigmentation, which is solid color pieces that give paint the desired hue. Next, color pigmentation with metallic or pearlescent flakes is added to either a solvent-based polyurethane or water-based resin. When the paint coats dry, the pigmentation is left behind and a top coat is sprayed on for protection. The purpose of automotive paint is not only for aesthetics, but to protect the car from nature’s elements, hence the top coat for protection. 

What are the layers of paint? 

The first layer is a phosphate treatment that goes directly onto the metal of the car, and is 5 microns thick. This phosphate treatment uses enhanced adhesion in which the phosphate coating provides a rough surface that promotes adhesion between the metal surface and the subsequent layers of paint.The phosphate coating creates a barrier that helps to protect the metal from corrosion and overall durability and appearance of the paint.

The second layer is an E-coat that is about 20 microns thick. The purpose of the Electrocoat Primer layer is to provide corrosion protection to the metal surface of the vehicle body. It acts as a barrier, preventing water, salt, and other corrosive materials from coming into contact with the metal surface.This is a corrosion-resistant coating that's electrically charged to attract and adhere to the metal surface. Electrical current is used to evenly coat metal panels with paint. E-coat promotes greater adhesion for the primer and all subsequent paint layers due to its hyper consistent application.

The third layer is primer, which can range from 20 to 30 microns thick. Primer is used on the car’s metal to create a uniform base for the next coats to go on, and to help against rock chips and scratches.

The fourth coat is called the base coat, but is essentially the color layer that ranges from 15 to 25 microns. Base coats with just solid color are thinner than those compared to coats with metallic or pearlescent properties.

The final top coat is the clear coat, and it is the thickest ranging from 40 to 50 microns. Clear coat is applied on top of the base coat to provide a glossy finish and protect the underlying layers from UV damage, weathering, and scratches. It is the thickest layer of your vehicle’s paint, generally making up about 33-42% of the entire layered system. The top coat can have a matte, glossy, or tinted finish. All of these layers work together to give a car a beautiful, lasting finish, but automotive paint isn't indestructible, and that is when paint correction plays a huge role.  

5 layers of automotive paint explained
Credit: Eastman Chemical Co./ K. Irvine, NIST

Here are some common types of paint defects:

Swirl Marks: Swirl marks are fine, circular scratches that appear on the paint surface. They often result from improper washing, drying, or buffing techniques. Swirl marks can be caused by using abrasive materials, such as rough towels or brushes, or by applying too much pressure while cleaning or polishing. Common result of automated car washes. They are more visible under direct light and can give the paint a hazy or dull appearance.

Deep Marring: Deep marring refers to more severe surface-level imperfections on the paintwork. These marks are deeper and more noticeable than regular swirl marks. Deep marring can result from using harsh abrasives or aggressive polishing techniques that remove a significant amount of clear coat or even reach the underlying layers of paint. These marks require professional correction and may need paintwork touch-ups to restore the surface.

Deep Scratches: Deep scratches are physical marks on the paint surface that penetrate through the clear coat and sometimes reach the base coat or primer layers. They can be caused by various factors, including contact with sharp objects, keying, or accidents. Deep scratches can be more challenging to repair and may require professional assistance, such as sanding, filling, and repainting the affected area.

Acid and Water Etching: Acid and water etching occurs when acidic substances, such as bird droppings, tree sap, or certain types of car wash chemicals, come into contact with the paint surface and cause chemical reactions. This can result in the appearance of dull spots or etchings on the paint. Acid and water etching can permanently damage the clear coat if left untreated for an extended period.

Buffer Marks (Holograms): Buffer marks, also known as holograms, are visible swirl-like patterns or wavy lines that result from improper machine polishing or buffing techniques. They are caused by using a rotary or dual-action buffer with incorrect pad or compound combinations, excessive pressure, or incorrect polishing motions. These marks can give the paint a distorted or uneven appearance under certain lighting conditions.

Auto paint defects and examples of coating thickness

How does paint correction fix your car's paint? 

Paint correction is a process that involves removing surface imperfections from a car's paintwork to restore its appearance. It typically involves the use of abrasive compounds and polishing techniques to carefully level the paint surface and remove defects such as swirl marks, scratches, and oxidation. By gently removing a thin layer of the clear coat and smoothing out the surrounding area, paint correction restores the paint's gloss, clarity, and smoothness, resulting in a significantly improved and more refined finish.