Just like Bluto and Popeye, the difference between auto body and standard paint is one of strength
Auto paint and standard paint are not the same. Sure, some car owners with the desire to save money on the upkeep of an old car have tried using house paint on their older vehicle. Others have tried it out on their classic car with the goal of adding some signature style to the refurbishing process. It rarely works.
Basically, there is a reason auto supply stores and auto body shops sell and use auto body paint, while home decorating stores sell house paint. One sort of paint is meant to adhere to wood, while the other is meant to adhere to metal.
It’s a case of one and one equalling two that the metal-adhering paint, specifically the automotive paint, is meant to be stronger than the house paint. That said, it’s obvious why those older vehicle owners and classic car buffs were disappointed in their painting efforts. It’s a sure bet the paint wore off much too quickly.
Basically, a paint job has two goals. If it does its first job well it makes the item it covers appear clean, presentable and attractive. However, that is not paint’s chief goal. The true and underlying goal of paint is to protect the item it coats by staying stuck to the item, thereby acting as a barrier between it and the elements. In short, it must be stronger than and outlast any and all of the elements bombarded against it. For example, interior house paint has as its particular goal the protection of the walls of the house it coats against mold, mildew, bacteria and possibly kid’s finger paints. Hopefully, it does its job well. Even if it does, however, it still ranks as a lightweight compared to outdoor paint, which in its turn must withstand rain, wind hail and snow right along with the mold, mildew, bacteria and gooey-fingered kids buffet encountered by interior house paint. Neither paint ranks as much more than an amateur, however, when compared to automotive paint. Not only does automotive paint have to withstand all the usual suspects, it must endure the conditions of the road as well. Those conditions entail not just rain, hail, sleet and snow, but dirt, mud, sand, salt and gravel. In fact, that dirt, mud, sand, salt and gravel, doesn’t just constitute just the lying down quietly versions. It covers the flying right into the vehicle versions as well.
It’s obvious from all of the above automotive paint has to create a truly durable shield around the vehicle it covers. That said, no one appreciates a lumpy coat of paint. All of which explains why an automotive paint job is a multi-coat process.
While a house painting job may require some primer and one or more layers of top coat, a car painting job entails several stages. A primer is the initial coat applied. It includes resin and fillers. The goal of the primer is to create an even surface for the later coats. After the primer comes a base coat with paint pigments, a thinner with organic solvents, meant to thin out the paint, a clear coat made up of further solvents, designed to protect the auto’s paint coat against scratches and finally a hardener to extend the life of the paint job. The result, which is a hard and long-lasting shell of paint, is one the car companies are forever attempting to improve upon. As a matter of fact, the outlook for 2012 is that many car companies will be using a product known in the industry as stone chip primer. It’s purpose is to deflect gravel and rock debris by laying down a plastic-like shield. Obviously, nothing in standard house paint comes close.
To sum up, house paint and automotive paint do share a common goal. Both are supposed to cover their intended product, fill in its imperfections, color it and protect it. To that end, house paint, like automotive paint, has pigments, solvents, binders and fillers. All similarity, however, ends right there. Automotive paint must be adhere to metal, not wood, and it must be stronger to face and endure a host of challenges house paint was never intended to endure.