Abstract <p>As a result of studying the regularities in the scattering of sludge and polishing powder wear nanoparticles during the polishing of copper and aluminum with dispersion systems of copper metaborate micro- and nanopowders in a dispersion medium of kerosene or water, as well as the formation of a deposit from these nanoparticles on the working surface of the lapping tool, it was found that the lapping tool surface can be reached only by the sludge particles scattered forward and by the polishing powder wear particles scattered backward, for which the differential cross sections varying within the limits of 2.3–102.0 Gb sr^–1 and 0.7–4.8 Mb sr^–1 significantly decrease with increasing separation between sludge nanoparticles, polishing powder wear nanoparticles, and a dispersion medium by dielectric permittivity. It was shown that the total scattering cross sections of nanoparticles σ_<i>m</i> and σ_<i>p</i>, varying within the limits of 0.05–1.78 Mb and 0.37–0.53 Mb, also decrease with increasing separation between sludge nanoparticles, polishing powder wear nanoparticles, and a dispersion medium by dielectric permittivity, and maximum σ_<i>m</i>/σ_<i>p</i> = 3.3 and minimum σ_<i>m</i>/σ_<i>p</i> = 0.1, which are characteristic of interaction between nanoparticles in the copper–kerosene and aluminum–water systems, indicate that the deposit on the working surface of the lapping tool will be more probably formed from sludge nanoparticles in the first case and from polishing powder wear nanoparticles in the second case. It was experimentally confirmed that a deposit of copper particles is observed on the surface of the lapping tool, when copper is polished with copper metaborate micro- and nanopowders in the dispersion medium of kerosene, and a deposit of copper metaborate particles is observed, when aluminum is polished in the dispersion medium of water.</p>