Abstract: The method of enhancing purity of a fused quartz body having opposed boundary surfaces, includes the steps of maintaining the body at a temperature above 1000.degree. C. and at the same time applying a polarizing potential across the boundary surfaces by electrodes in contact with the boundary surfaces so that at least some of the residual impurity ions in it are made to migrate away from one of the boundary surfaces towards the opposite one of the boundary surfaces thereof and are subsequently discharged at the opposite boundary surface. To avoid surface contamination or deformation each of the electrodes is a gaseous electrode of an at least partially ionized helium, argon, neon, krypton, xenon, nitrogen or hydrogen gas or a flame produced by combustion of hydrogen, methane, propane, butane or acetylene. The temperature during the maintaining step is advantageously from 1500.degree. C. to 2100.degree. C.