DoIt Industries Electro Filing & Polishing Machine is equipped with an electro-chemical process that removes metal from articles. It improves the surface finish by reducing the surface roughness by leveling micro-peaks and valleys. Due to its ease of operation and its usefulness in filing and polishing irregularly-shaped objects. Doit Industries ELECTRO FILING & POLISHING has become a common process in the world of the production of Jewellery. Same liquid for all carats.