I. Prolonged exposure to sunlight One of the main reasons colored bottles fade is prolonged exposure to sunlight. UV rays break down the color pigments or coatings used on the surface of the bottle, causing them to dull or discolor. This is especially true for spray-painted or frosted bottles with lighter shades.Colored bottles stored in high heat or direct light are more likely to experience color changes. Stacking or rubbing during shipping can also cause scratches and color loss. II. Use of poor-quality paints by suppliers Many manufacturers use low-grade coatings or processes to reduce production costs, but this method will cause the products to fade. Poor-quality materials cannot withstand high temperatures, humidity or friction during transportation. III. Deficiencies in materials and processes 1.Uneven pigment dispersion: Insufficient mixing of the masterbatch leads to color differences.When the melting point difference between the masterbatch and the su...