If you’ve ever painted a wall in your home, or observed a professional painter do it, you may be familiar with the primer. Primer is a base coat you put on a surface before applying one or more topcoats of the actual color you want. Primers are typically light colored and help cover the previous color and stop it from seeping through the topcoat. One coat of primer can do the work of two topcoats, and primer is usually less expensive.

Vehicle painting also uses primers and they play mostly the same role. However, there are peculiarities to vehicle painting primers that are important to note. Here’s what to know about primers and vehicle painting.

Vehicle painting and auto body repair

Vehicle painting is often part of auto body repair (often the last part before the final inspection). If a vehicle has been in any kind of collision, even one at slow speed, it will likely need at least a paint touch up. Sometimes a vehicle suffers a dent that doesn’t scratch or chip the paint. And, sometimes, auto body repair technicians can fix these dents without damaging the paint job. These are paintless dent repairs, or PDRs. 

But apart from PDRs, any collision repair that affects the body of the vehicle probably needs a paint job. Vehicle painting is also necessary to repair scratches that occur from driving against objects such as bushes or pillars, vandalism, or even hailstones. Lastly, vehicle painting is sometimes necessary just to spruce up a car’s paint job after years of exposure to the elements. Your nearest auto body shop will be able to determine the best solution for the painting needs for your repaired vehicle.

Vehicle painting and primer

When painting a vehicle, it’s often necessary to use primer first. There are cases in which, if an auto body repair shop doesn’t use automotive paint primer—or the right type of primer—that the collision repair won’t be fully complete. 

The benefits of automotive primers

Here are some advantages of using primer before vehicle painting:

• A uniform base color: As mentioned earlier, a primer is important for adding a base color. Vehicle paint primers are often grey, black, or white, as these shades improve coverage for the topcoat, especially with lighter or more transparent colors.
• Corrosion prevention: For metal surfaces, primer is great for sealing in the metal, limiting its exposure to the elements, and thereby preventing rust from forming underneath the paint.
• Smoothing imperfections: Some primers can fill in minor scratches, abrasions, and surface irregularities, creating a smoother finish for the topcoat.
• Improved adhesion: Primer helps the topcoat of paint stick to the surface of the vehicle. There are primers that can improve adhesion for metal, plastic, and fiberglass surfaces. Without primer, the paint might peel or chip prematurely.
• Enhanced durability: A properly primed surface results in better paint durability, reducing the risk of peeling, cracking, and fading over time.

Different types of primer

Whether you’re going to an auto body repair shop for a vehicle painting or doing it yourself, it’s critical to know that not all primers are the same. There are several types of primer, and each is more suitable for a different purpose. Here are some types of vehicle primer:

Self-Etching Primer

Self-etching primer contains an acid that chemically bonds to metal, so it provides excellent adhesion for metal-surfaced bodies. These primers also maximize corrosion resistance. Self-etching primer is best on steel and aluminum surfaces, but it may require a sealer before painting as it doesn’t fill imperfections as well as other primers do.

Epoxy Primer

This primer also offers super adhesion and corrosion resistance, but unlike self-etching primer, epoxy primer is suitable for application to metal, fibreglass, and even on old automotive paint. Epoxy provides a strong, waterproof barrier and it can be used as a base coat for other primers and paint. However, it’s important to smooth out any imperfections before applying the epoxy primer, as it can be very difficult to sand after applying it.

Urethane Primer

Also known as high-build primer, urethane is great for smoothing out surface imperfections, such as scratches and sanding marks. It provides a thick, sand-able surface for a smooth, even base. Unlike the previous two primers, Urethane doesn’t offer great corrosion protection on its own, but it is, perhaps, the most common type of primer.

Polyester Primer

Polyester might be the best primer for heavy bodywork, such as filling deep scratches and minor dents. Collision repair technicians can use it like a sprayable body filler, applying a thick layer they can sand later. Polyester primer isn’t very flexible, so it’s best for rigid surfaces and may require a sealer between it and the topcoat.

Sealer

Sealers aren’t great for filling scratches, but they are great for creating a smooth, uniform surface. Sealers are often suitable for adding on top of other primers, such as urethane.

Lacquer Primer 

If you have a newish vehicle and you’re going to a professional, reliable auto body repair shop, you probably don’t have to worry about lacquers. These are older and less common today. However, if you’re restoring an old vehicle, a lacquer primer coat might be helpful. Lacquer isn’t particularly durable and can shrink over time, which is why epoxy and urethane primers have largely replaced it.

The right automotive primer for the right job

It’s tricky to know which primer (if any) you need for your collision repair or paint touch-up. It’s beneficial to go to a professional auto body repair shop that has access to all the primers that drivers might need. That way, they can apply for the right primer for a given vehicle painting job