1. Frosting process
Frosting (also known as frosting) refers to immersing the glass bottle in a prepared acidic liquid (or applying an acidic paste), using strong acid to erode the surface of the glass bottle, and at the same time, the hydrogen fluoride ammonia in the strong acid solution causes crystals to form on the glass surface. Therefore, if the frosting process is done well, the frosted glass surface is extremely smooth, and the crystals form scattering to produce a hazy effect.
According to the “Glass Process Technology Manual” (2022 edition), the acid used in the frosting process is usually composed of hydrofluoric acid and sulfuric acid, and its ratio directly affects the final surface effect. Temperature control is also a key factor, and the treatment effect is generally best at 18-25°C.
If the surface is relatively rough, it means that the acid has severely eroded the glass, which is a manifestation of the immature craftsmanship of the frosting master. Or some parts still have no crystals (commonly known as no sanding, or the glass has spots), which also means that the master’s craftsmanship is not well controlled. This process technology is difficult. The best manifestation of this process is the appearance of sparkling crystals on the glass surface, which is formed under a critical condition. The main reason is that the hydrogen fluoride ammonia is almost exhausted.
The frosting process has certain safety risks to the environment and operators. It needs to be carried out under professional protective equipment and strictly abide by the waste liquid treatment specifications.
2. Sandblasting process
This process is very common. It uses sand particles shot at high speed from a spray gun to hit the surface of the glass bottle, so that the glass bottle forms a fine concave and convex surface, thereby achieving the effect of scattering light, making the light pass through and forming a hazy feeling. The surface of the glass product with sandblasting process feels rough. Because the glass surface is damaged, the originally transparent glass looks like white glass in the light. The process difficulty is average.
The materials used for sandblasting are usually alumina sand or quartz sand, and the particle size range is generally between 60-220 mesh. According to the “Technical Standards for Surface Treatment of Packaging Glass” issued by the China Packaging Federation, the sandblasting pressure is usually maintained at 0.5-0.7MPa, which can ensure the uniformity and consistency of the surface treatment.
The sandblasting process can achieve local treatment, and by covering the area that does not need to be treated, a pattern or text is formed, which has obvious advantages in brand logo design. Compared with frosting, the surface microstructure produced by sandblasting has greater irregularity, making the light scattering more significant.
3. Difference
The two processes are completely different. Frosted glass bottles are more expensive than sandblasted glass bottles, and the effect mainly depends on the needs of users. Some unique glass bottles are not suitable for frosting. From the perspective of pursuing nobility, frosting should be used. Sandblasting can be completed by general factories, but it is not easy to do frosting well.
According to data from the International Glass Craft Association, the application of frosting technology in high-end perfume packaging accounts for 65%, while sandblasting is more common in the mid-range market, accounting for about 72%. This difference is mainly due to the different positioning of cost and visual effects.
Frosted glass bottles are formed with a sandy feel when they are produced, with a strong texture, but limited patterns; sandblasted glass bottles are first cut into a mold with paper according to requirements and then sprayed with patterns, so that any graphics you want can be engraved. The surface particle size of frosting is finer than that of sandblasting.
From the perspective of durability, the frosted surface has a more stable crystal structure and better wear resistance than the sandblasted surface. During long-term use, the sandblasted surface may gradually become smooth due to friction, while the frosted surface can better maintain the original texture.
| Process type | Implementation method | Surface texture | Pattern flexibility | Cost | Technical difficulty | Environmental protection | Applicable fields |
|---|---|---|---|---|---|---|---|
| Frosted process | Acidic liquid erosion | Smooth and delicate, with crystals | Limited | High | High | Low (professional waste liquid treatment is required) | High-end perfume and cosmetic packaging |
| Sandblasting process | High-speed sand hitting | Rough, uneven | Very high | Low | Medium | Medium (dust problem) | Mid-range products, personalized customization |
4. Glass coloring technology
In addition to surface treatment, glass coloring is also an important process to enhance the beauty of glass bottles. The main coloring methods include:
Glass coloring: Add metal oxides such as copper (blue), cobalt (dark blue), chromium (green), manganese (purple), etc. to the molten glass to make the entire glass body present a uniform color.
Surface spraying: A thin film is formed on the glass surface by spraying colored paint, which has the characteristics of low cost and rich colors, but poor wear resistance.
Electroplating coloring: A metal film is formed on the glass surface by electrochemical methods. Common ones are gold, silver, chromium, etc., which can produce a metallic luster effect.
Ion exchange coloring: The glass is soaked in molten salt containing coloring ions to exchange surface ions to form a colored layer with high durability.
Different coloring methods can be combined with frosting or sandblasting processes to create a richer and more diverse visual effect to meet the packaging needs of different products.
