Final answer:
Abrasive powder is used on items like leather and rough plastic to reduce shine and improve surface smoothness.
Step-by-step explanation:
The type of powder used on items like leather and rough plastic is typically abrasive powder. Abrasive powders consist of small particles with randomly oriented surfaces, which leads to diffuse reflection and reduces shine. Some common types of abrasive powders include pumice, calcium carbonate, kaolinite, quartz, soapstone, and talc. These powders are used as polishing agents to remove imperfections and smooth the surfaces of leather and rough plastic.