There are many alternative processes competing with EMI Shielding Compounds such as foils and conductive fabrics, metallic inner shields, and plastics with a conductive coating. Conductive paints are the most common method of applying a conductive surface coating to plastics, but vacuum metallization is gaining popularity.
While it is rather straightforward to compare the advantages and disadvantages of coatings versus compounds, it is more complicated to compare the shielding capabilities of the two methods. Compounds shield primarily by absorption, while coatings shield primarily by reflection.
The coating industry utilizes surface resistivity as a mechanism to denote shielding capability. However, for absorption shielding (where electrical conductivity is mostly within part walls), there is little correlation between surface resistivity and shielding capability. Volume resistivity is a better indicator of shielding effectiveness.