Practical control of glass bottle spraying

After the color matching and pre-treatment of the bottle body are completed, the spraying construction is the core step of coloring and shaping. With the same pigment and the same glass bottle, differences in construction operations can cause significant variations in the depth of color and the flatness of the paint surface of the finished product. When mass-producing wine glass bottles and aroma bottles, a unified spraying standard is the key to controlling color differences and reducing scrapping.

First, control the viscosity of the paint mixture. The color-adjusted glass-specific paint needs to be mixed with a dedicated thinner to adjust the consistency. The standard viscosity is to apply - 4 cups for 18-30 seconds. Simple judgment method: After stirring the paint, lift the stirring rod 20 centimeters. If the paint liquid continuously forms fine lines and briefly drips and breaks, it indicates an appropriate viscosity. If the paint liquid is too thick, it is prone to produce pitting particles. If it is too thin, it will cause large-scale sagging after spraying, weaken the covering power, and the base color of the glass will show through and become mottled.

Secondly, standardize the usage parameters of the spray gun. The air pressure of the conventional air spray gun should be stabilized at 0.3-0.4MPa, and the nozzle should be kept at a distance of 200-300mm from the bottle body. Spray at a uniform speed in a horizontal direction, and apply multiple layers of color in a single thin spray. It is strictly prohibited to apply thick spray in a single spray. Automated electrostatic spraying can increase the utilization rate of coatings by more than 30%, making the coating more uniform and suitable for single-color full-bottle spraying. Manual spray guns are highly flexible and are often used in the processing of gradient and local color registration glass bottles.

The control of the workshop environment cannot be ignored. The spray booth must be independently enclosed and equipped with an air filtration system. The floor should be swept twice a day to reduce dust. Fluctuations in temperature and humidity are the main causes of color differences and craters. When the temperature is below 18℃, the atomization of the coating deteriorates. When the humidity is above 70%, water vapor remains inside the paint film, resulting in bubbles and white spots after drying. When the humidity is below 60%, the air is dry, static electricity accumulates more dust, and the paint surface is covered with fine particle defects.

After the spraying is completed, it cannot be directly baked at high temperature. A 5-8 minute leveling time should be reserved to allow the paint to naturally spread out and eliminate the marks left by the spray gun. Then, the temperature should be raised in stages for curing. Light colors and macaron color series have weak covering power and need to be sprayed in 2 to 3 layers, with each layer leveling at intervals. Dark and solid color paints can be formed in two layers. For pearlescent paint, the spraying thickness needs to be controlled; if it is too thick, the fine pearlescent texture will be lost.

Strictly adhering to the spraying operation standards can not only restore the standard color card during color matching but also avoid common defects such as sagging, bubbles, and particles, reduce raw material loss, and stabilize the appearance quality of colored glass bottles.