We have a detailed article on the testing procedures of partially fritted glass optical & thermal properties. For partially fritted glasses, the daylight reflectance property concerns many customers. This article aims to present some opinions from us on the daylight reflectance of partially fritted glasses.
Partially fritted glasses: glass or non-glass material?
If you are a textualist and adhere to the texts strictly, partially fritted glasses are obviously made of glass, as the word “glass” appears in the name, and you should stop reading this post from here.
If you are not a textualist and open to some discussions, below are some explanations on the differences between glass and non-glass materials in terms of optical characteristics.
There are 3 types of material surfaces, in terms of optical characteristics:
- With specular reflectance only
- With mixed reflection
- With diffuse reflection only
In our opinion, conventional glasses and glasses with ceramic frit are distinct in optical characteristics. For a partially fritted glass, it is more reasonable to classify its clear part as glass material and classify its fritted part as non-glass material.

Specular reflection only
Optical characteristics:
- With specular reflection only
- Diffuse reflection is negligible
For such materials:
- Diffuse reflectance = 0%
- Total reflectance = specular reflectance
Examples:
- Conventional glasses
- Materials with mirror finish
- Metallic coating on glasses

Mixed reflection
Optical characteristics:
- With both specular reflection and diffuse reflection
- Both components are not negligible
For such materials:
- Total reflectance = diffuse reflectance + specular reflectance
Examples:
- Most general facade and roof materials with certain glossiness
- Glasses with ceramic frit

Diffuse reflection only
Optical characteristics:
- With diffuse reflection only
- Specular reflection is negligible
For such materials:
- Specular reflectance = 0%
- Total reflectance = diffuse reflectance
Examples:
- Materials with matt and rough surfaces: e.g. roof tiles, rough granites
Disclaimer
- The information presented above is our opinion. It is not reviewed, agreed, or approved by any external parties.