The light transmittance of small appliance glass is a core indicator of its optical performance, directly affecting the product's appearance, texture, and user experience. Its transmittance is influenced by multiple factors, including raw material purity, manufacturing process, surface treatment, internal structure, light wavelength, environmental conditions, and functional design. A systematic optimization strategy is needed to improve transmittance.
The purity of raw materials is fundamental to ensuring high transmittance. Glass's main component is silicon dioxide. If impurities such as iron and chromium oxides are mixed into the raw materials, they will form color centers that absorb specific wavelengths of light, leading to a decrease in transmittance. For example, ordinary soda-lime glass, due to its high iron content, typically has lower transmittance than ultra-clear glass; while ultra-clear glass, by selecting low-iron raw materials, can significantly reduce light absorption, achieving a transmittance of over 90%. Therefore, selecting high-purity raw materials and strictly controlling impurity content is the first step in improving transmittance.
The precision of the manufacturing process directly affects the glass's internal structure. In traditional glassmaking processes, if the molten glass remains in the furnace for too long or the temperature is not properly controlled, defects such as streaks and inclusions can easily occur. These microscopic inhomogeneities scatter light, reducing transmittance. Modern float glass processes, by optimizing melting temperature, refining time, and forming parameters, can produce glass with a smooth surface and uniform internal structure, significantly improving transmittance compared to traditional processes. Furthermore, using electro-flushing technology to accelerate glass refining or introducing ultrasonic debubbling devices to reduce internal bubbles can further reduce light scattering loss.
Surface treatment technology is a key step in optimizing transmittance. The roughness of the glass surface directly affects the reflection and refraction of light. Untreated glass surfaces have micron-level unevenness, causing some light to be scattered rather than transmitted. Processes such as chemical etching, mechanical polishing, or flame polishing can reduce surface roughness and decrease light scattering. For example, AG glass (anti-glare glass) uses surface etching to create a uniform microstructure, reducing reflectivity while maintaining high transmittance, making it suitable for small appliance screens that require reduced ambient light interference.
Internal structural design must balance functional requirements with transmittance. Some small appliance glass requires heat insulation, explosion-proof, or decorative functions, which may be achieved by adding coatings or composite structures. For example, Low-E glass uses a low-emissivity coating to reflect infrared light, which slightly reduces visible light transmittance, but this can be maintained at a high level by optimizing the coating thickness and material selection. For decorative glass requiring high transmittance, screen printing or digital printing techniques can be used to create transparent or translucent patterns on the glass surface, meeting design requirements while avoiding excessive light obstruction.
The matching degree between light wavelength and material absorption characteristics affects transmittance. Glass has different absorption coefficients for different wavelengths of light. For example, ultraviolet light is easily absorbed by iron ions in glass, while infrared light may be partially blocked due to molecular vibrations. For small appliance glass requiring high transmittance in specific wavelengths, selective light transmission can be achieved by adjusting the glass composition or adding rare earth elements. For example, adding cerium oxide enhances ultraviolet absorption, making it suitable for oven viewing windows requiring UV protection; while adding titanium oxide increases infrared transmittance, making it suitable for heating equipment requiring rapid heating.
Environmental conditions and usage scenarios pose challenges to the long-term stability of light transmittance. High temperature, high humidity, or chemically corrosive environments can cause the glass surface coating to peel off or the internal structure to change, thus reducing light transmittance. For example, the glass panels of small kitchen appliances need to withstand the corrosion of oil fumes and cleaning agents, therefore requiring chemically resistant coatings or tempered glass to enhance surface hardness. Furthermore, glass exposed to sunlight for extended periods may experience a decrease in light transmittance due to ultraviolet aging, necessitating the addition of ultraviolet absorbers or the use of anti-aging coatings to extend its lifespan.
Balancing functional design with light transmittance requires consideration of user needs. For example, refrigerator door glass needs to achieve both high light transmittance and heat insulation, which can be achieved by using vacuum-insulated glass or double-glazed structures; while microwave oven viewing windows need to strike a balance between light transmittance and microwave leakage prevention, typically using metal mesh laminated glass. By simulating user scenarios and optimizing design parameters, it is possible to ensure that the glass maximizes light transmittance while meeting functional requirements.
