Powders having an irregular shape and must therefore be measured in a container through an optical window or alternatively can be measured directly by pressing into a solid tablet form.
When measuring through a window the glass will affect the absolute values, which adds a systematic error. Normally color measurements are relative, compare a sample with a standard and the error is compensated. If absolute values are needed the ColorLite spectrophotometers can be switched to “Powder” mode. In this mode a base calibration is made through the glass window, which compensates the error.
As the powder density i.e. air to grain ratio will affect the results measuring in the tablet form is the most accurate method.
This means three methods are available:
- Powder is measured in a special glass cuvette – suitable for relative measurements as values are biased with a systematic error
- Powder in measured in a special glass cuvette in a powder mode
- Powder in measured after being pressed in a tablet form – most accurate with best repeatability.
What is needed?
For measuring powders in a glass cuvette we offer a complete Powder-Set. This has a light proof cap to prevent ambient light affecting the results.
For measuring powders in tablet form ColorLite has a complete package, this includes a form in which the powder is pressed. The press its self is needed but not included in the set.