There are actually several different methods used today to effectively remove graffiti. Traditional methods include sanding or chipping graffiti off, while chemical solutions include the application of aluminum oxide or silicon carbide to dissolve the graffiti paint. Sometimes high concentrations of glass beads, sand or walnuts are used to effectively “blast” the graffiti off of a surface. With all of these methods, the freshly cleaned surface can then be repainted or refurnished as necessary.
That said, a more modern solution is called “soda blasting”. Using Sodium Bicarbonate in high concentrations, soda blasting cleans away graffiti safely and efficiently. It is also notable for not damaging the surface the way other methods can, resulting in less maintenance needed after the graffiti is removed (the surface may not have to be repainted). Soda blasting can also be used to removed rust and other forms of corrosion from walls and other kinds of structures.
The right method will depend of course on the type of surface and the extent of the graffiti, but soda blasting is quickly becoming the most popular removal method. Unlike more traditional methods that can leave marks in a surface (and echoes of past graffiti), soda blasting can make a surface look brand new! It is also worth pointing out that it is a more environmentally friendly method thanks to the absence of harsh chemicals and non-water soluable cleaning materials. Therefore, less cleanup is required in the area after graffiti is removed.