A method of manufacturing a vacuum insulated glazing (VIG) unit, the method comprising disposing a sealing composition around a periphery of first and second substantially parallel glass panes to define a cavity and form a pre-sealed VIG unit; flowing gas comprising a reactive oxygen species into the cavity; heating the sealing composition to a first temperature; and heating the sealing composition to a second temperature to form the peripheral seal and a sealed cavity between the first and second glass panes.