Below is a list of EMI Coating manufacturers from Ayer, Massachusetts. EMI coating is sprayed on the interior of electronic device housings in order to protect sensitive electronic equipment from electromagnetic interference. EMI, or electromagnetic interference, is the magnetic field which is created by electrical currents; EMI can travel along wires, electrical circuits and conductors, while radio frequency interference (RFI) is radiated electromagnetic “noise,” which travels through the air as radio waves.