金属涂装前,必须将表面的黏附物（氧化皮、油污等）除去,并进行适当的表面化学转换,以增加涂膜的附着力,延长涂膜的使用寿命,充分发挥涂层的保护作用和装饰效果。而前处理液的配比及稳定性起着决定性的作用。所以前处理理化分析是不可缺少的工序,是保证前处理质量的重要一环。“,”Substance adhering on surface（such as oxide film and oil stains） must be removed to facilitate corresponding chemical conversion before metallic painting.In this manner,the adhesiveness of paint films is strengthened and their duration extended,thereby absolutely display the protection and decoration effects of the paint films.In this process,the ratio and stability of pretreatment liquor plays a decisive role.Therefore,the physical and chemical analysis of pretreatment is an indispensable technique and an important step to ensure pretreatment quality.