Baffle wafers of polycrystalline silicon are placed in non-production slots of a support tower for thermal processing monocrystalline silicon wafers. The polycrystalline silicon is preferably randomly oriented Czochralski polysilicon grown using a randomly oriented seed, for example, CVD grown silicon. An all-silicon hot zone of a thermal furnace may include a silicon support tower placed within a silicon liner and supporting the polysilicon baffle wafers with silicon injector tube providing processing gas within the liner. The randomly oriented polysilicon may be used for other parts requiring a rugged member, for example, within a silicon processing chamber and for structural members.