A multi-functional method and apparatus are disclosed for producing a low hydroxyl ion-containing core rod from a tube suitable for the production of low-water optical fibers. The method and apparatus combine the use of process steps of (1) hermetically sealing a tubular quartz handle of a tubular porous core preform to a tube used to feed the porous preform into a sintering furnace, (2) dehydration and sintering, and (3) elongation of the sintered preform under vacuum, all without exposing the preform’s central aperture surface to ambient atmosphere.