The color of bronze powder and the influencing factors
The Chinese Journal of Nonferrous Metals research shows:
The color of bronze powder can be described by the three elements which is color hue, brightness and purity. The hue of bronze powder is only related to the alloy composition, and has nothing to do with the particle size, shape and distribution of the bronze powder. At the meantime, the brightness and purity are related to the pigment orientation in the ink layer, the particle size , the particle shape and the particle distribution of the bronze powder flakes, but not the composition.
The neat pigment orientation, large sheet diameter, and narrow particle size distribution can obtain high brightness and purity.
In the test range, pale gold powders with little difference in composition have the same hue, and the same rules exist for rich gold powders.
The hues of rich gold powder and pale gold powder are quite different.
In addition, the brightness of bronze powder will decrease due to storing time, and the color will become darker and yellower.
To prevent and minimize the issue we should keep it in the room temperature environment ,avoid direct expose to the light, and use it within 2 years.