A whiteness meter is used to measure the whiteness of flat surfaces or powders.

This useful equipment is regularly used in various industries like textile, construction, paper, and plastic.

With this, you can measure the white of dyes and paints, textile prints, building materials, plastics, cardboard, and paper.

Whiteness meter manufacturers make different types of meters to cater to the needs of their clients.

The whiteness of any surface refers to the reflectance of it to blue light.

It is shown as a percentage relative to the reflectance of the surface of the magnesium oxide standard plate, which is irradiated by blue light.

MEXTECH is a reputed name in industrial equipment sector that makes top-quality tools and equipment.

How does it work?

A whiteness measuring device has a light source and an optical measuring system that measures the reflection of the light and thus determines the whiteness of the surface.

Standards used for this measurement are ISO R457 (ISO 2469). After initial calibration, you can directly use the whiteness meter. The meter has a big memory to store up to 250 measurement data. Modern meters can be connected to a computer using a serial interface. Thus, you can have data history for better analysis.

As far as its working principle is concerned, there is a tungsten lamp that acts as the light source. A light beam is projected onto the sample at an angle of 45° degrees. Photocell is used to receive the luminous flux diffusely reflected by the sample in the normal direction.

The output photocurrent received by the photocell is directly proportional to the whiteness of the surface. The whiter the surface, the higher the photocurrent.

Typically, you have a filter installed between the main light source and the sample. This filter absorbs visible light with a wavelength above 500nm and a part of blue light. The filter has higher transparency so that UV light with a wavelength of 360-400nm.

There is an additional filter that eliminates the reflected UV light, it allows the blue light with a wavelength of about 440nm. It enters into the photocell.

Calibration Procedure

Calibration is extremely important in all types of testing and measuring instruments.

1. First, you should turn the selector switch to the upper part. Now turn the knob in the anticlockwise direction and adjust the galvanometer to zero position. There is an adjustment knob that can be used.
2. You should put the standard whiteness board on the sample tray. Now adjust the reading knob to the whiteness value marked on the whiteness board. Now turn the selector switch to the lower part and adjust the coarse and fine adjustment knob. Thus, the light point of the galvanometer indicates the zero position. Now, turn the selector switch to the upper position.
3. Now you should remove the whiteboard and replace it using a black tube. You should turn the reading knob to zero. Turn the selection switch to the lower part and adjust the adjustment knob to make the light point indicate the zero position.
4. Now you should turn the selection switch pull to the top. Repeat points 2 and 3. The adjustment has to be done using a standard whiteness board.

Read More: Choose the Best Whiteness Meter for Your Industry