Abstract: A method is proposed for preventing so-called halo-blocked apertures in color picture tubes. The halo-blocked apertures are caused by insulative negatively-charged particles attached to the inside surface of the shadow mask which deflect the transmitting portions of an electron beam. The method comprises depositing a conductive primary metal film on the insulative particle to render the particle conductive so that the particle cannot deflect the beam. This conductive film is applied during the initial tube processing after the tube has been agitated and oriented so as to dispose any loose insulative particles within the tube to a location where the conductive primary metal film can be deposited thereon, and prior to the step of depositing a getter material.