What is yellowness Index?
What is yellowness Index?
Yellowness Index is a number calculated from spectrophotometric data that describes the change in color of a test sample from clear or white to yellow. This test is most commonly used to evaluate color changes in a material caused by real or simulated outdoor exposure.
How is yellowness measured?
Yellowness indices are used chiefly to measure these types of degradation. Where X, Y, and Z are the CIE Tristimulus values, and the coefficients depend on the illuminant and observer as indicated in the table below….Yellowness Index.
| C/2 | D65/10 | |
|---|---|---|
| CX | 1.2769 | 1.3013 |
| CZ | 1.0592 | 1.1498 |
What is the whiteness index?
It is the measure which correlates the visual ratings of whiteness for certain white and near-white surfaces. The two most commonly used methods for computing a whiteness index are: CIE Whiteness Index and Ganz-Griesser Whiteness Index.
What is Hunter whiteness?
In general, a material will exhibit high whiteness if the material reflectance has high and even reflectance, near 100%, across the visible spectrum. For a PRD Perfect White of 100% reflectance across the visible spectrum, WIH will have a value of 100, falling off sharply as the sample color gets darker or more yellow.
What is Berger whiteness?
Berger – this whiteness index is specified for illuminant C and 2-degree observer functions only. In the case of non lightened samples, standard illuminant C, i.e. light without a UV component, can be used for measurement. Standard illuminant D65 must be used for measurement of optically lightened papers.
How is whiteness calculated?
W = 4B-3G where B and G refer to tristimulus colorimeter readings. W = 100-[(100-L)2 + (a2 + b2)]1/2 where L, a, and b refer to coordinates in Hunter’s L, a, b Color Difference Equation.
What is the difference between whiteness and brightness?
Brightness measures the ability of a paper to reflect blue light. Whiteness on the other hand measures paper in the same way that the eye sees it. Whiteness measures the ability of paper to reflect all colors of light.
How is whiteness measured?
To measure color or shade, we use a spectrophotometer. The spectrophotometer also measures Whiteness. Whiteness is a measurement that goes beyond brightness by looking at the shade of white paper, considering reflected light in the red, yellow, and green as well as the blue region of the spectrum.
What is the whitest paper?
CIE 160 – The whitest coated paper in the world.
What is CIE paper?
The CIE measure of whiteness is a measurement of the light reflected by the paper across the visible (daylight) spectrum. The CIE have set a standard of D65 illumination which is a standard representation of outdoor daylight under which the amount of light reflected is measured.
What is Epson paper?
Engineered for outstanding prints Epson specialty papers are comprised of four to eight layers per sheet. These layers work together to absorb ink, lock in vibrant colors and give you instant-dry, superior-quality prints. See the difference between Epson premium glossy paper and generic plain paper.
Does radiation affect the yellowness of polypropylene?
Effects of Radiation Exposure on Physical Properties Yellowness Index. The yellowness index of each form of polypropylene increased after exposure to gamma radiation. The most dramatic increase occurred in the standard Homopolymer material. The least increase was noted in the non- phenolic Impact Copolymer.
What is the ASTM designation for yellowness index of plastics?
The ASTM Designation D1925-70 which is as Standard Test Method for Yellowness Index of Plastics. ASTM Designation E313-73 which was reapproved in 1993 and it is the Standard Test Method for Indexes of Whiteness and Yellowness.
What are the different types of yellowness indices?
Apparently,there are two main types of yellowness indices which are used in industrial setup and they include: The ASTM Designation D1925-70 which is as Standard Test Method for Yellowness Index of Plastics. ASTM Designation E313-73 which was reapproved in 1993 and it is the Standard Test Method for Indexes of Whiteness and Yellowness.
What is the ASTM whiteness index?
The American Standards Test Methods (ASTM) defines whiteness and yellowness indices for paper, paint and plastic although it is widely used in many industries. The E313 Whiteness Index is used for measuring any near-white material.
