The selection of pigment carbon black can be based on coloring characteristics or physical and chemical properties. The choice of types of carbon black for coloring is primarily determined by the required darkness of the finished product. Very fine pigment carbon black can meet high darkness requirements for coloring; products like PE garbage bags, plastic bags, and cable materials only require a moderate level of darkness, and can use carbon black varieties with lower specific surface area and higher structure. In plastic coloring, minor errors in the measurement and mixing of carbon black can lead to significant color differences, so it is advisable to use larger particle size, lower coloring strength, and low pigment carbon black. This allows for a slightly higher carbon black dosage, with relatively smaller measurement errors, and offers the advantages of better dispersibility and lower cost. For gray plastics, fine-grained pigment carbon black often presents a brownish gray, while coarse-grained pigment carbon black can produce a bluish gray.