Reasons and solutions for rainbow spots on glass

Everyone loves rainbows, but I believe no one likes rainbow spots on their own glass. Today, we will analyze the reasons and solutions for rainbow spots on glass.

What is a glass rainbow spot?

The appearance of stripes, blocks, and other rainbow like patterns on glass is called glass rainbow spots. The probability of rainbow spots appearing on tempered glass is usually higher than that on ordinary glass.

There are two common situations where rainbow patterns appear on glass:

1、 Rainbow spots on tempered glass caused by uneven stress distribution

Tempered glass will generate compressive stress on the surface layer and tensile stress inside the glass, resulting in differences in density at different positions of the same surface layer from the surface to the center. Macroscopically, the relatively irregular atomic arrangement results in tempered glass becoming an anisotropic material. When a beam of polarized light passes through tempered glass, the path that allows visible light to pass through becomes a tortuous path. Due to the difference in optical density inside the glass, this beam of light will be decomposed into two polarized light beams with different propagation speeds, namely one beam of light with relatively fast propagation speed and the other beam of light with relatively slow propagation speed. When two beams of light formed at a certain point intersect with a beam of light formed at another point, there is a phase difference at the intersection point due to the difference in light propagation speed. At this point, the two beams of light will interfere. When the amplitude direction of the two beams of light is the same, the light is strengthened, producing a bright field of view visually, that is, rainbow patterns. So, the more uneven the stress distribution of tempered glass, the more obvious the rainbow pattern phenomenon generated on the surface.

The solution to the rainbow spots caused by uneven stress distribution in glass is to ensure that the temperature in each area of the glass is highly uniform and consistent before air cooling. During the air cooling process, maintaining a uniform cooling speed and wind speed can reduce the occurrence of rainbow spots in the glass.

2、 Rainbow spots caused by mold growth on glass due to moisture

During the storage, transportation, and even installation and use of glass, due to the erosion of water vapor or other chemical products in the air, rainbow spots, white spots, white mist, etc. are prone to appear on the surface, causing a decrease in transparency and smoothness.

The glass rainbow spots generated in this situation can be promptly detected and cleaned using 8% hydrofluoric acid or glass mold remover, both of which can achieve good removal effects. If left untreated for a long time, it can make it difficult to remove glass rainbow spots. If rainbow spots have existed for a period of time and are difficult to remove by cleaning, fine polishing powder can be used to polish the glass surface, which helps reduce the visual impact of rainbow spots.