Classification for specialized chemicals and solutions used for chemical and physical surface treatment of metal parts and products. Includes pre-plating treatment agents (degreasers, pickling agents, activators), anodizing solutions, chemical conversion treatment agents (phosphate treatment, chromate treatment), electrolytic polishing solutions, passivation agents, and rust prevention treatment agents. Distinguished from paints and coating agents, this category focuses on liquid and powder treatment agents specialized for chemical modification and pre-treatment of metal surfaces. Essential chemical groups for manufacturing industries used to improve surface quality and provide functionality to automotive parts, electronic components, and precision machinery parts.