Causes And Solutions To Bubble Problems in High-end Glass Wine Bottles

In the production of glass bottles, bubbles remain a difficult quality challenge to completely resolve. While generally not impacting the actual performance of the bottles, bubbles can significantly detract from the product's appearance. Especially in the manufacture of high-end glass bottles, their presence is strictly prohibited. Due to numerous uncertainties in production, bubbles are often difficult to fully control, resulting in significant economic losses for companies. Glass melting is a complex physical and chemical process encompassing multiple stages, including silicate formation, glass formation, and clarification and homogenization. The clarification stage is particularly critical for eliminating bubbles. As the temperature rises, the viscosity of the molten glass gradually decreases, creating conditions for bubble elimination. During this process, a gradual equilibrium is established between the gases within the bubbles, the gases within the kiln, and the physically dissolved and chemically bound gases in the molten glass, causing visible bubbles to float to the surface and eventually disappear.

The elimination of visible bubbles during the clarification process occurs primarily through two pathways: first, the bubbles increase in size, accelerating their rise and bursting upon reaching the surface; second, the gas components within small bubbles dissolve in the molten glass, absorbing the bubbles and causing them to disappear. The size of the bubbles and the viscosity of the molten glass are key factors in determining their ability to successfully float. According to Stoke's law, the rising speed of bubbles is proportional to the square of the bubble radius and inversely proportional to the viscosity of the molten glass. To further explore the bubble elimination mechanism in high-white glass, we calculated the viscosity of the molten glass at different temperatures and compared the performance of other glass formulations. Furthermore, we combined the temperature at the clarification point and the distance the bubbles rose to estimate the rising time of bubbles of different diameters. Practice has shown that increasing the melting temperature can accelerate the rising of bubbles larger than 0.2 mm and shorten their discharge time. However, for bubbles smaller than 0.2 mm, temperature adjustment is required to encourage their absorption into the molten glass.

During the cooling phase of the molten glass, the bubbles gradually shrink due to the constant pressure of the gas cooling. Due to the surface tension of the molten glass, the pressure within the bubble increases as its radius decreases. When the temperature drops to a certain level, the saturation pressure of the gas in the molten glass falls below the pressure within the bubble, and the gas within the bubble is released into the molten glass. This process causes the bubble radius to continuously decrease, ultimately leading to complete absorption by the molten glass. In summary, the removal of large bubbles and the absorption of small bubbles are two essential steps in the glass clarification process. The former requires appropriate temperature and sufficient reaction time, while the latter requires a certain temperature drop gradient. Failure to meet any of these conditions may lead to the appearance of bubbles in the final product.