When painting a car, boat, or other vehicles, one of the most important steps happens before the paint booth. This critical preparation involves a process called sanding. The purpose is to remove previous paint, smooth dents, and scratches, and prepare a quality surface for the new paint job. Without the auto sanding process, even the best paint will not yield the optimum finishing project that a professional paint job demands.
The important paint prep of auto body repair is accomplished by using abrasives. Abrasives are made of minerals such as Aluminum Oxide to cut, grind, and smooth other surfaces through friction. The abrasive materials wear away unwanted softer materials such as old coats of paint and smooth the surface welcoming new paint. Abrasives are also used to finish a surface through polishing.
Sanding can be accomplished by sanding by hand using sandpaper and a sanding block, but most heavy-duty professional jobs will be performed with a sanding disc. Sanding discs are circular abrasives whose purpose is to remove paint, materials, defects, rust, and corrosion from different surfaces. Sanding discs are attached to an electric-powered sander like an angle grinder or orbital sander.
Sanding discs are available in two types: paper discs or film discs. The more traditional form, paper discs are dry discs. They come with either adhesive backs or hook & loop (Velcro) that attach to an electric sander. Paper discs are manufactured in different sizes, hole patterns, and types of abrasive materials depending on your needs.
The other form of sanding disc is the film disc. The backing is usually made of polyester to make it flexible and tear-resist. The backprints are color-coded to assist in identifying the grit which brings us to an important aspect: grit number.
Choosing the correct sanding disc is about the right grit. The grit is a numerical rating that describes the size of the abrasive particles on the sandpaper or sanding disc. The Lower the grit numbers, the coarser the disc will be, and the higher the grit, the finer it will be. Grit numbers can range anywhere from 40 to 4000+.
Knowing which grit sandpaper to use depends on the type of job and what step in the process you are in. Whether you are repairing a small scratch or repainting an entire automobile, there are multiple steps to a sanding project. Failure to use the right grit can cause bad results, poor quality, or damage to the surface.
The first step in a common auto body sanding begins with removing all of the old paint and primer from the vehicle. Use a low-grit sanding disc of around 80-grit for this. Next, you need to sand any body filler with a higher grit disc of about 120. You are now ready to apply the primer coat to the car. Once this coat is completely dry, you can use a higher disc such as a 220-grit to smooth out the primer. Finally before spraying paint, once again increase the grit to around 380 to ensure a smooth final paint finish.
All of the above suggested grits fall under low-grit which is under 400, you may also require medium to high-grit discs in your body shop. Grit from 400-600 is considered medium, and high grit is 1000+. High grit is for small repairs such as minor scratches and imperfections and for super-smooth finishing using a wet-sanding technique. CTW International has two high-quality abrasives for whatever auto body sanding job you require.
The CarSystem Paper Sanding Disc boasts very high cutting power and long life. The innovative hole system creates higher suction power and extends the life of the disc. This universal paper grinding wheel is Alumina grain and suitable for all work from coarse to fine sanding. Advantages include a high removal rate and high efficiency. These low to high grit discs are available from 40 grit to 800 grit.
The CarSystem Film Sanding Disc is a high-performance film-based disc made of aluminum oxide. They are extremely quick cutting with a special coating for even sanding of old and new paint layers. These discs have high, long-lasting cutting power. Available in 80 grit to 2000 grits, and are suitable for coarse to fine sanding.
Discs also available from CTW International are CarSystem Excenter Back Pads and CarSystem Interface Pads. If you need control powder, view the Dry Coat Back and Dry Coat Orange for surface highlighting. If you need any help with abrasives and sanding products, contact us today.