为解决一起少见的车身表面涂层灰点污染问题，从人、机、料、法、环等方面排查原因，并利用光学显微镜（ OM）和傅立叶变换红外光谱仪（ FT-IR），逐层表征并分析清漆层、色漆层和预喷涂层，确定缺陷产生的根本原因，给出解决方案。结果表明：长时间搅拌后，预喷涂涂料中的黑色浆料析出，造成预喷涂层与色漆层发生混溶，产生灰点污染。随着后续预喷涂材料配方的改进，以及长效管理措施的实施，彻底消除了灰点污染的缺陷。

The cause of rare gray spot contamination defects on car body surface coatingwas investigated in this study. Optical microscopy（OM）and Fourier infrared spectroscopy（FT-IR）were used to characterize these contamination defects from car body surface coatinglayer to pre-coat layer. A series of tests and detections，including man，machine，material， method，and environment aspects，were implemented to check the true cause of the defects. Itwas revealed that the contamination defects were result from pre-coat black slurry penetratingto the base coating layer and formed the grey point defect after long-time stirring. With theimprovement of the pre-coating material formula as well as effective long-term managementmeasures were implemented，the contamination defects were eliminated entirely.