The terminology used in the auto body world is not something you can just learn from normal conversations at your local pub. These are terms that are very specific to their industry and can be very important when learning about how to do body work and paint or if you’re just trying to be educated when having collision work done. Below we listed some of the most common terms used and a simple definition of what they mean.
Substrate- This is the technical term for an uncoated or bare surface before paint or primer has been added. This can be any surface from metal, fiberglass, plastic, or even carbon fiber. Generally this term is used when speaking generally about how to apply a coating or prep the surface for the particular product.
Body Filler- Sometimes called “Bondo” after a well known body filler brand. This is putty like substance that is applied over a damaged area to fill and smooth out the damage. This product is normally a two part putty that is extremely durable once it dries. Correct use of body filler is an industry accepted solution to light imperfections in the surface.
Primer- This is sometimes called a “sealer” but primer is used to seal up the surface. The surface can be bare or coated with another paint or coating (like body filler). Primer comes in many forms and each have a different purpose. As a rule of thumb primer is the foundation that a paint job is built off of.
Sealer- Sometimes interchanged with the term “primer”. This is usually applied over an area that has pre-existing coatings to seal it all in. This can be used over old paint or primer or over top of the body filler and primer you’ve just done. This seals everything under it and is a good base for paint and clear coat.
Base Coat– The first coat of a Base Coat-Clear Coat system. This is the first lay er of color laid over top of your primer or sealer. A true base coat paint system must be top coated with a clear coat to be sealed properly.
Single Stage Paint- A type of paint that doesn’t require a clear coat over it. This type of paint isn’t used as much in modern day auto body shops, but is still used regularly in the DIY and Restoration auto paint hobby.
Clear Coat– This is also called the “gloss coat” sometimes and is the last coating applied to a paint job. It is required on base coat-clear coat systems but doesn’t always have to be shiny. Clear coats come in all levels of gloss and can be wet sanded and buffed to give a high gloss, flat surface.
Chip Guard- This is usually a temporary film or coating that protects the paint and clear coat from damage in high-risk areas like the front of a hood, behind wheels, and the face of the bumpers. These generally are made to be nearly invisible and shouldn’t damage the paint or clear underneath.
Cutting and Buffing- A final step in painting a car is the cutting and buffing process. This is basically a number of steps that level the paint or clear coat, remove imperfections, and bring up the gloss in the finish. This starts with sanding out major imperfections all the way up to using a rotary tool with multiple steps of buffing pads and compounds.
Wet Sanding- When wet sanding you are wetting the surface and sanding it to remove imperfections. The water helps lubricate the panel reduces the possibility of making heavy scratches in the panel. This is usually done to flatten the surface and is done before the buffing/polishing stage.
Orange Peel- When paint or clear coat has an uneven finish like the surface of an orange peel it will have “orange peel”. This can be caused by improper distance from the panel when spraying, travel speed of the paint gun, or mixture of paint or clear coat for weather conditions. Orange Peel can usually be corrected through wet sanding and will level out with some work.
Sags and Runs- These are imperfections in clear coat or paint. If you’re using a base coat – clear coat system and the run is in the clear coat you can often times scrape or cut the sag or run down and wet sand it flat. This is caused by application error when spraying. Check your travel speed or distance and angle of your paint gun when spraying.