The quality of electrostatic spraying depends not only on the equipment and management standards but also on whether the coating material meets the specific requirements for electrostatic application. Electrostatic spraying requires coatings with low resistivity; a range of 5–50 MΩ·cm is considered optimal. Coating resistivity is determined not only by the resin content but also by the choice of solvents. Consequently, solvent additives are frequently used in practice to adjust the resistivity to the desired level.
While electrostatic spraying requires low-resistivity coatings, many standard coatings have relatively high resistivity. To lower the resistivity, solvents with appropriate polarity are commonly added to the coating formulation.
Airflow velocity within the electrostatic spray booth is also a critical factor. The booth's exhaust system is primarily designed to remove solvent vapors generated during the spraying process, keeping their concentration below the lower explosive limit (LEL) to ensure operational safety. Airflow velocity should be maintained between 0.3 and 0.7 m/s, as excessive speed can adversely affect the spraying results. The exhaust system should be equipped with an airflow regulation mechanism.
