A liquid-crystal photo-alignment layer that is composed of polymer stabilized azo dyes is provided, where a polymer network is introduced in the photo-alignment layer for stabilization. The dental whitening composition comprises a hydrogen peroxide source; a carrier exhibiting a viscosity of about 40,000 cps to about 60,000 cps; and, optionally an additive such as thickeners, buffering compounds, chelating agents, surfactants, flavorants and artificial sweeteners. The developing fluid dissolves the UV-exposed top portion of the aggregate and a polishing slurry is formed of the developing fluid and the released abrasive particles. The used plating substances are purified to remove at least some of the byproduct and then the purified plating substances are combined with at least one component before passing back into the plating cell to reuse at least some of the plating substances. In another embodiment, the blocker can be mounted to the landing gear.