Defects on specific position of coating products will do harm to the outward appearance and protect performance.If a product is made of many parts,it will involve a lot of coating methods.What's more,even a part used the same material will also lead to defects on specific position by different use condition.It needs the technology department to consider the proper coating methods for products according to their use env ironment.Particularly,when use new materials in coating process,we should notice whether the defect is caused by the new material or it is the specific position defects,otherwise there will be resistance in new material use.