Select carbon black based on coloring characteristics or physical properties. The choice of the type of carbon black for coloring is primarily determined by the required darkness of the finished product. Extremely fine pigment carbon black can achieve high darkness requirements for coloring. For products like PE trash bags, plastic bags, and cable materials, which only require a moderate level of darkness, lower surface area and higher structure carbon black types can be used. In plastic color matching, minor errors in the measurement of carbon black and mixing can lead to significant color variations, so it's advisable to use larger particle size, lower coloring strength pigment carbon black. This allows for slightly higher carbon black usage, smaller measurement errors, and benefits from better dispersion and lower cost. For gray plastic, fine particle pigment carbon black often results in a brownish gray, while coarse particle pigment carbon black can produce a bluish gray.