Another advantage of using a sandblaster to prep your items for powder coating is it gives the item a surface profile or "tooth". Think of sanding a piece of metal with sandpaper and you see the thousands of little scratches that it leaves. These scratches create high points and low points in the metal. This is called a profile. A profile allows the powder coat to seep into all of these high and low points which allow it adhere to the part much better than if the metal was completely smooth. While sandpaper does give your item profile, the sanding marks are in straight lines, a sandblaster creates a uniform textured finish all over the entire surface of your part, and in places that no sandpaper can reach. Without a surface profile, powder coating can just peel off the surface, this is called delamination.