photochromic glass

chemistry

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July 2, 2026

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Photochromic glass is a material that changes color when exposed to light. This effect is achieved through photochromic compounds, which exist in both colorless and colored states. Exposure to specific wavelengths of radiation causes the compound to change to its colored form. The material then reverts to its colorless state either in darkness or when exposed to different wavelengths of radiation.1

This reversibility is a key characteristic of photochromism, allowing for instant image formation without processing. Photochromic materials can be used in various applications, including sunglasses, where they darken in bright light and become clear in low light conditions. Some photochromic glasses contain silver halide crystals that decompose upon light exposure, forming a visible silver deposit. In the dark, the halogen recombines with the silver, causing the image to fade.1

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industrial glass
Photosensitivity
Traditional photochromic eyeglasses are generally alkali boroaluminosilicates with 0.01 to 0.1 percent silver halide and a small amount of copper. Upon absorption of light, the silver ion reduces to metallic silver, which nucleates to form colloids about 120 angstroms in size. This is small enough to…
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Traditional photochromic eyeglasses are generally alkali boroaluminosilicates with 0.01 to 0.1 percent silver halide and a small amount of copper. Upon absorption of light, the silver ion reduces to metallic silver, which nucleates to form colloids about 120 angstroms in size. This is small enough to…
Read More

technology of photography
Photochromic systems
Photochromic materials can be negative- or positive-working. With some photochromic compounds the dye image can be rendered permanent by optical or other treatment.
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Photochromic materials can be negative- or positive-working. With some photochromic compounds the dye image can be rendered permanent by optical or other treatment.
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