Thermal metal spraying or cutting (arc/air) processes produce large quantities of ultrafine particles which cause irreversible clogging of industrial dust collectors in the long-term. This study, conducted on a test system equipped with a pleated filter cartridge confirms the high clogging capacity of these fumes, and also shows that current pulsed-jet cleaning methods are ineffective. The study has shown that the pressure drop across filters rises during filtration primarily due to the presence of ultrafine particles in the aerosol. This explains why cyclone type pre-separation has proved inefficient in preserving filtration capacity. Filter pre-coating could overcome the problem of ineffective cleaning (if used in off-line mode), but this technique generates large quantities of waste requiring specific handling. Future research should be oriented either towards improving filter cleaning or developing alternative separation techniques. (C) 2012 Elsevier B.V. All rights reserved.