The process of spraying, drying and curing colored glass bottles

After color matching and spraying, the final process of drying and curing is to lock in the color and solidify the coating. Many manufacturers only focus on color matching and spraying, and casually simplify the baking process. As a result, the finished glass bottles have after-sales problems such as color fading when wiped, whitening when soaked in water, and paint peeling when bumped, which greatly damages the reputation of orders. Glass-specific coatings are classified into three types: water-based acrylic paint, epoxy paint, and powder coatings. The baking standards are completely different and need to be controlled separately.

Water-based glass paint is mostly used in beauty and aromatherapy glass bottles. It is baked in stages at low temperatures: first, it is pre-baked at 120℃ for 10 minutes to evaporate moisture, then heated to 150℃ for constant temperature curing for 12 minutes, and finally cooled naturally by air. Direct high-temperature baking will cause the water vapor inside the paint layer to expand rapidly, resulting in the paint film bubbling and the surface fogging. The originally prepared bright color will become dull and lackluster.

Epoxy solid color paint and metallic color wine bottle coating have a higher curing temperature, with a constant temperature range of 160-180℃ and a holding time of 10-15 minutes. If the temperature is insufficient, the resin cannot be fully cross-linked, the hardness of the paint film is low, and the color will fade with slight friction. When the temperature exceeds 200℃, organic pigments decompose due to heat, resulting in severe color differences. The fading of light colors such as red, yellow and orange is particularly obvious.

The curing temperature for powder-coated glass bottles should be 180-200℃. The distance between the drying tunnel and the spray room should be controlled within 6 meters to avoid prolonged cooling after spraying, which may cause the coating to solidify prematurely and result in uneven coating. After baking is completed, rapid cooling with cold water is prohibited. High-temperature glass is prone to cracking when exposed to cold, and the paint film may also become brittle and peel off due to thermal expansion and contraction. It needs to be air-cooled slowly to room temperature before being taken off the line for packaging.

Glass bottles of the same batch should be placed uniformly, and the stacking distance should be kept well-ventilated to prevent the bottle bodies from sticking to each other and scraping off the paint surface during baking. When baking light-colored transparent spray-painted products, separate zones should be set up. The evaporation of dark pigments can easily contaminate the light-colored bottle body, causing mixed color pollution. For pearlescent and metallic glitter glass bottles, the holding time should be shortened. Prolonged high temperatures will damage the luster of pearlescent particles.

By precisely controlling the baking temperature, duration and cooling process, the paint film can possess the properties of being resistant to alcohol wiping and not fading after long-term soaking in water, perfectly retaining the standard color of the previous color adjustment, and significantly enhancing the durability and appearance texture of the finished colored glass bottles.