What is a common use for body filler in auto body repair?

Body filler is primarily used to fill and straighten sheet metal damage in auto body repair. This material, often composed of a polyester resin reinforced with glass beads, is designed to adhere well to metal surfaces and can be sanded down to achieve a smooth finish. When a vehicle’s body experiences dents, dings, or rusted areas, body filler provides an effective way to restore the surface by filling in the imperfections and allowing for a nearly seamless repair.

The primary purpose of body filler goes beyond just filling gaps; it also helps in reshaping the contours of the vehicle's body, ensuring a uniform appearance after the repair is completed. This is crucial in maintaining the aesthetic and structural integrity of the vehicle, especially when preparing for paint application, as a smooth and well-prepared surface leads to better paint adhesion and overall finish quality.

In contrast, the other options suggest functions that are not typical uses for body filler. Sealing joints against moisture is usually done with sealants or weather stripping, creating electrical insulation might involve materials like rubber or plastic compounds, and primers serve a different purpose related to paint application rather than body repair.