What are the techniques for sanding automotive putty?
3 Answers
Techniques for sanding automotive putty: 1. Generally, the polarity between primer, putty, and topcoat should be similar or basically similar to obtain reliable adhesion and interlayer bonding strength; 2. Select the appropriate putty based on the thickness and purpose of the filling layer, generally categorized into filling type, intermediate type, and spray-filling type; 3. Determine the sanding tools and methods according to the layers, area, thickness, and shape of the applied putty. Automotive putty, also known as body filler, is widely used in the automotive repair and manufacturing industries. Whether it's for repairing accident-damaged vehicle bodies or surface defects caused by mold issues, transportation problems, or welding deformations during the manufacturing process, body filler is typically used for repair and leveling. This is followed by processes such as intermediate coating and topcoat application to meet the appearance requirements of the vehicle.
When sanding car putty, I usually start by selecting sandpaper and proceed from coarse to fine grit. For example, I begin with 80-grit sandpaper to remove large uneven areas, then switch to 180-grit for finer work. The motion should be gentle and even—avoid applying too much pressure to prevent sanding through the putty layer. Follow the curves of the car body slowly and avoid back-and-forth scrubbing to prevent scratches or deep marks. Always use the wet sanding method: lightly spray water on the sandpaper to reduce dust and protect respiratory health. Don’t forget to wear a mask and goggles, as excessive dust inhalation is harmful. After sanding, check the surface by hand—it should feel smooth and even. If you detect small bumps or unevenness, lightly sand again before painting. Patience is key—taking it step by step ensures a flawless finish and saves time on rework later.
When doing this job in my own garage, I usually start with wet sandpaper, using coarse grit like 100 for large uneven areas, then switch to finer grit like 220 for surface refinement. In terms of technique, I prefer using a circular motion with light pressure, moving back and forth to avoid over-sanding any single spot and creating depressions. A handy tip is to frequently add water to keep the surface moist, which helps control dust and prevents scratches. After finishing, I inspect the surface under lighting to check for hidden imperfections and ensure smoothness. Also, always wear protective gear like disposable masks and gloves—safety first. Though the process can be a bit messy and tiring, it saves a lot of money compared to going to a repair shop.
