Abstract: A method of coating a filter medium in a flowing gaseous stream, the method comprising: directing a gas stream along a feed path; combining with said gas stream a multiplicity of finished glass dust particles; positioning a fibrous filter medium along said feed path downstream of the point at which the glass dust particles are combined with said stream, the glass dust particles forming a coating on said filter medium to assist in the capture thereon of hazardous waste material in said stream, when said stream contains such material; maintaining the temperature of the gas stream below the softening point of the glass particles; and intermittently removing the particulate coating material and any such hazardous waste material from the filter medium and collecting the same; and a system for accomplishing the same.