A disposable core structure supports a porous polymeric brush utilized in the treatment of substrates. The disposable core structure includes an exterior surface featuring a plurality of waffle-like recesses separated by walls having sufficient thinness to permit fabrication by injection molding. The core structure includes an end adapted to permit attachment to a rotating member of an associated substrate handling apparatus. The end of the core structure further includes an opening to a bore in fluid communication with pores on the exterior surface of the core structure. Injection molding allows economical mass production of the core structure, permitting it to be fitted with the polymeric brush in a clean room setting and then be permanently fixed to a single brush. This avoids problems of bunching, tearing, wrinkling and stretching associated with replacement of brushes in the field that requires the brush to be fitted around a conventional nondisposable core.