Car fenders are painted like all automotive sheet metal. If you are in an auto repair shop, first of all: generally, all the items we buy have a layer of electrophoretic paint, and there is no need to spray primer. You can use 800 sandpaper and water mill directly, as long as you smooth all the places where the top coat is sprayed. Second: then dust removal, dust removal is a key link, the first dust removal must be wiped with a high-pressure air gun, and then after the spraying equipment is turned on, the cloth should be wiped with a special dust removal cloth. Third: Different paints have different proportions. Adjust the paint in the right proportion. In general, curing agent should be added to the top coat. If it is ordinary paint, it can be sprayed on both sides, because there is no need to spray bright oil. If it is metallic paint, there is no need to add curing agent. Metallic paint has strict requirements for spray guns, so it must not be fast. It should be slower than spraying ordinary paint, otherwise it will be easy to flood. After the first spray of metallic paint. Then spray metallic paint for the second time. This side must be pressed evenly without exposing the bottom, and then polished, which is what we call varnish. A curing agent was added to the varnish. As mentioned above, the curing agent should be added to the general plain paint, and it should be carefully rubbed before spraying. Then spray bright oil on both sides, and give priority to the second time, without orange peel and showing the bottom. Fourth: the paint used in general auto repair shops is a two-component paint, and the baking temperature should not be too high, just 30-40 degrees.