The Opacity Tester, or Opacity Meter, is a specialized scientific tool that quantifies the ability of a substance to prevent the transmission of light rays. By taking measurements for light transmission, scattering, and diffuse reflectance, this device provides an accurate value of the percent opacity, where 0% stands for total transparency and 100% for full opacity.
How it works
Essential Features of Modern Laboratory Models
- High Precision Benchtop Design: Dust-free specimen containers and durable, high-grade powder-coated cases that avoid light pollution from surroundings.
- Digital Calibrations: High precision microprocessors (with direct LED or touch screen monitors) that offer a resolution of 0.01% for plastic film opacity testing.
- Integration with Data: The modern benchtop models have provisions for connecting through USB or RS232 ports and transferring live quality control results to databases.
Which industries use Opacity Testers?
Here are some of the industries where opacity testers are used-
- In the packaging industries for food, pharmaceutical products, and dairy items
- In paper mills
- For commercial printing purposes
- In automotive paints
- Manufacturing liquid inks
Technical Working Principles
A laboratory opacity tester typically operates on one of two fundamental optical setups:
1. Light Transmission Method (Transmittance)
Usually applied in plastic films, laminates, and pipes (for example, R-PVC or C-PVC).
- Principle of operation: Monochromatic or regulated light source (typically emitting light in the narrow range of visible spectrum, i.e., from 540 nm to 560 nm, or analog D65 daylight light source) emits light right through the sample.
- Measurement: Photoelectric cell positioned on the opposite side detects emitted light. The measurement device measures both the intensity of the incident light (I0) and the intensity of the transmitted light (I).
2. Diffuse Reflectance Method (Contrast Ratio)
Standard measurement technique for paper, printed packaging, textiles, and coatings.
- Mechanism: The sample is placed on two contrasting backgrounds – first a white background and then a black background.
- Calculation: The device calculates the reflectance of the sample placed over the black background, R0, and the reflectance of the sample placed over the white background, Rw.
What materials can be tested with an Opacity Tester?
Different types of materials and substances are tested using the opacity tester. This basically varies based on the application and the type of industry using it. Here is a list of a few materials whose opacity is tested-
- Plastic films and laminates
- Paper and cardboard
- Textiles
- Plastic pipes, fittings, and mouldings
- Paints and varnishes
- Inks
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Q : What is an Opacity Tester?
A : An opacity tester is basically a kind of device to test the opacity of a material, which is how much light it allows to pass through it.
Q : Why is opacity testing important?
A : The opacity testing is important basically to ensure quality control and maintain exact standards in different industries to keep light out, ensuring products are hidden and maintain a certain visual appearance.
Q : Are Opacity Testers used for quality control?
A : Of course! In fact, QC and QA are the main reasons for which opacity testers are used. They act as objective gatekeepers of the manufacturing process and testing laboratories.
