What are the surface coloring methods for glass?

Surface coloring of glass refers to the application of metals, metal oxides, etc. on the surface of glass to form transparent, semi transparent, or opaque color coatings. Blue SnO2 film and gold Fe2O3 film can be prepared by coating SnCl4 and FeCl3 on the surface of glass using chemical thermal decomposition method.

Metal films such as gold, silver, and copper, as well as metal oxide films such as In2O3, SnO2, and TiO2, can be prepared using methods such as vacuum evaporation, vacuum negative sputtering, and reactive sputtering. Due to differences in film thickness and refractive index, interference and reflection films of different colors can be formed.

In the float glass production line, electric float glass or thermal spraying method can be used to produce colored glass with surface coloring. Glazed glass can also be made by printing or spraying glass colored glaze.

How to dye the interior of glass？

① Ionic coloring. It is a compound that adds transition elements such as cobalt (Co), manganese (Mn), nickel (Ni), iron (Fe), copper (Cu), etc. to glass material, existing in an ionic state in the glass. Due to the transition of their valence electrons between different energy levels (ground state and excited state), it causes selective absorption of visible light and coloring, such as cobalt blue, manganese violet, nickel green and other colored glasses.

② Compound colloidal particle coloring. It is to add sulfur or selenium compounds (such as CdS, CdSe, etc.) to glass containing zinc (ZnO), forming CdO, ZnS, ZnSe, etc. in the glass, and then perform two heat treatments below the annealing temperature to form CdS, CdSe and grow into very large colloidal particles, which color the glass due to light scattering, such as selenium red, cadmium yellow and other colored glasses.

③ Coloring of metal colloidal particles. It is to add oxides that are easily decomposed into metallic states (such as gold, silver, copper, etc.) to glass raw materials, dissolve them in an ionic state in the glass, transform them into atomic states through heat treatment, aggregate and grow into colloidal particles, and color them by absorbing visible light due to light scattering, such as gold red, copper red, silver yellow and other colored glasses.

④ Semiconductor coloring. Adding colorants such as CdS, CdSe, CdTe to the glass material results in a continuous absorption zone without an absorption peak in the visible light region, with a steep boundary between the transparent zone and the absorption zone. Unlike the aforementioned coloring mechanisms, its color changes with the ratio of CdS/CdSe. For example, when CdS is present, it approaches orange, when CdSe is present, it appears red, and when CdTe is present, it appears black. This means that they move towards longer wavelengths in the order of O2-, S2-, Se2-, and Te2-. According to the semiconductor band theory, the electrophilic potential of these anions decreases in sequence, and their valence electrons can be excited to the conduction band (excited state) using lower energy (near visible light) light, causing them to cut short waves and enter the visible light region, resulting in glass coloring.