How to use a spectrophotometer measure solid colors?

As we all know, there are ten million colors that we can distinguish. The quality criterion “color” is becoming more and more important in every industry. Uniform color influence customer’s likes and dislikes. This is of particular important when the individual components of the final products are manufactured at difference company sites, or even more complicated when several supplier are involved. Nevertheless, in the end the color must be right.

Visual color perception is influenced by different color sensitivities from person to person(mood,age.etc), varying environments such as lightness and color. This is a digital world, more and more people will be more willing to believed the data rather than judgement from the manufacture, in that way, a color measuring machine is very important for the quality control department.

Standards for color perception

Color perception is depend on the interaction of three elements: light source, object and observer.

Item 1: color changes with the light source. So when we compare color difference, the illuminants have to be agreed and used. The visible spectrum is from 400 to 700nm.

Generally speaking, the important illuminants are Daylight D65, C, A,f2 & f11.

Item 2: without an observer there would be no color. Reflected light from a colored object enters the human eye through the lens and strikes the retina. And today, the observer is the spectrophotometer which stimulate the brain to produce the impression of color. To determine the sensitivity to the receptor,systematic visual tests were done by the CIE 1931 and 1964, based on the results,the degree 2 and degree10 observer were standardized, representing a small and large field of view,respectivily.

Item 3 object: Optical properties of an object are the only variables that need to be measured.

Color System combine data from three elements: light source, observer and object which is recommended by the CIE and widely used today, is the CIELAB system.

How to Measure Particle Color? Instructions for Using a Particle Spectrophotometer

In the process of color difference detection for particulate matter, a series of difficulties are often encountered due to the unique characteristics of particulate matter. These difficulties make color detection complex and challenging. However, with the development of technology, the emergence of advanced instruments such as spectrophotometers has provided new solutions for color difference detection of particulate matter. 

Challenges in detecting color difference in particulate matter

Uneven shape and distribution: Particles vary in shape and size, resulting in an uneven spatial distribution. This unevenness severely affects the distribution and uniformity of color, making it difficult to accurately measure color differences. 

 Light Influence: The surface properties of particulate matter cause optical phenomena such as reflection and refraction of light on its surface. These phenomena not only affect color observation but also make color measurement more complex and uncertain. 

 Changes in quantity and concentration: The quantity and concentration of particulate matter are also important factors affecting color measurement. As the quantity and concentration of particulate matter change, the depth and saturation of the color also change, making color measurement more difficult. 

Principles and Applications of Spectrophotometers

A spectrophotometer is a precision instrument based on spectroscopic and photoelectric detection technologies. It separates white light emitted from a light source into different wavelengths, which are then irradiated onto a sample. The instrument detects the sample's absorption, reflection, and transmission of light. By comparing the intensity of the light passing through the sample with that not passing through the sample, parameters such as the sample's chromaticity and color difference can be determined. 

 In the detection of color difference in particulate matter , the application of spectrophotometers has the following advantages: 

1. High-precision measurement: The spectrophotometer has high-precision measurement capabilities and can accurately measure the color differences of particulate matter, even the slightest color difference can be captured. 

2.  Wide applicability: The spectrophotometer is suitable for various particulate samples, whether solid particles or suspended particles in liquids, and can be effectively measured. 

3.  Non-contact measurement: The spectrophotometer adopts a non-contact measurement method, which avoids direct contact with particulate matter samples, thereby reducing the risk of sample contamination and instrument damage.

Instructions for using a particle spectrophotometer Measure Color

A particle spectrophotometer is an instrument used to measure the color of particles. It can accurately measure the color attributes of particle samples, including hue, lightness, and saturation. This instrument has wide applications in many industries, such as food, cosmetics, pigments, and plastics. This article will introduce how to use a particle spectrophotometer to measure particle color. 

 I. Preparatory Work Before using a particle spectrophotometer, the following preparations need to be made: 

 1. Ensure that the particulate sample is thoroughly mixed and free of large particles or impurities. 

 2. Clean the measuring cup to ensure there are no residues or dirt. 

 3. Turn on the particle spectrophotometer and let it warm up for a few minutes to allow the instrument to reach a stable state. 

II. Measurement Steps The following are the steps for measuring particle color using a particle spectrophotometer: 

 1. Place the measuring cup on the instrument and ensure that the lid of the measuring cup is tightly closed. 

 2. Press the "Start Measurement" button on the instrument, and the instrument will automatically perform the measurement. 

 3. Wait a few minutes until the instrument completes the measurement and displays the results. The measurement results will include attributes such as hue, lightness, and saturation of the particulate sample. 

 4. Record the measurement results and conduct further analysis or comparison as needed. 

III. Precautions When using a particle spectrophotometer, the following precautions should be taken: 

 1. Ensure the instrument is placed on a stable workbench to avoid affecting the measurement results. 

 2. Avoid any strong vibrations or shocks during the measurement process. 

 3. When measuring multiple samples, the measuring cup must be kept clean, and it must be ensured that there is no cross-contamination between each sample. 

 4. If the particle sample is magnetic, special attention should be paid to the placement of the instrument to avoid interference from the magnetic field. 

 5. Before using the instrument, it is recommended to carefully read the instruction manual and ensure you understand the correct operating procedures. Regular calibration and maintenance are also recommended to ensure its accuracy and stability.

Methods for detecting the color of powdered objects

The detection of color in powdered substances is crucial in many industries, including but not limited to the chemical, plastics, coating, and food industries. Accurate measurement of powder color requires specialized techniques and tools. The following are methods for detecting the color of powdered substances: image.png 

 I. Preparation of tools and samples 

1.  Colorimeter: Select a colorimeter suitable for powdered materials, ensuring it has sufficient accuracy and stability.

2. Powder test kit: A special powder test kit is used to load powder samples to ensure that the sample surface is flat and the color is uniform during measurement.

3. Standard sample: Prepare a standard sample of known color as a reference.

4. Cleaning tools: a cloth or brush for cleaning the colorimeter measuring head and powder test kit. 

 II. Sample Preparation  

1. Sampling: Take an appropriate amount of sample from the powder to be tested to ensure that the sample is representative.

2. Filling the test box: Evenly fill the powder test box with the extracted powder sample, ensuring that the surface is flat and without protrusions.

3. Cleaning: Before measurement, use a cleaning tool to gently remove any impurities that may be attached to the measuring head or test box. 

 III. Instrument Calibration 

Perform black and white plate calibration according to the colorimeter's instruction manual to ensure the accuracy of the measurement results. 

 IV. Measurement Operation

1. To measure the standard sample: Align the measuring head of the colorimeter with the surface of the standard sample, press the measurement button, and record the color data (L*, a*, b* values) of the standard sample.

2. To measure the sample: Align the colorimeter's measuring head with the sample surface in the powder test box in the same manner, press the measurement button, and record the sample's color data. 

 V. Data Analysis 

Calculate color difference: 

1. Use a color difference formula (such as ΔE*ab) to calculate the color difference between the standard sample and the test sample.

2. Evaluation results: Determine whether the measured color difference is within an acceptable range, based on industry or customer requirements. 

 VI. Precautions Avoid contamination: 

1. During sampling and measurement, ensure that any possible sources of contamination are avoided, such as hand oils, dust, etc.

2. Maintain consistency: When measuring multiple samples, maintain consistency in measurement conditions and methods to ensure comparability of results.

3. Regular maintenance: Perform regular inspections and maintenance on the colorimeter according to its maintenance requirements to ensure its long-term stable operation.

Spectrophotometer model:

There are two classess of instruments use to measure color 45/0 (it uses 45 degree circumferential illumination and 0 degree viewing perpendicular to the sample plane.such as NS800)
& sphere geometry(It illuminates the sample diffusely by means of a white coated integrating sphere such as YS series spectrophotometer )

Conclusion:

Only measurements taken under the some conditions can be compared. Therefore, it is necessary to noted the following information in a color measurement report: color instrument(geometry), illuminant / observer, color system, sample preparation.

3nh offer a complete line of benchtop and portable spectrophotometer, colorimeter and chrome meter for color measuring.  In a live demo via Zoom, Teams etc. you will get a detailed impression of how our color measurement devices colorimeter work and can talk directly to our colorimetry experts about your application.

If your are interested in our machine, please don’t hesitate to contact me by email service@3nh.com, whatsapp & wechat ID: +8613510310267, skype: clara3nh.

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