Color and Brightness Measurements

Color and Brightness Measurements

Eurolab our staff at our plant in Turkey is actively participating in standards organizations and are familiar with evaluation techniques and reporting scales. Visual assessment reports detail all observed defects such as cracking, blistering, peeling, chalking, adhesion, discoloration, and corrosion. All visual ratings are performed under standard lighting conditions to ensure accurate and reproducible results.

Examples of visual assessments (and applicable methods) include:         

  • Chalk - ASTM D4214, ISO 4628-6
  • Blistering - ASTM D714, ISO 4628-2
  • Cracking - ASTM D661, ISO 4628-4
  • Control - ASTM D660, ISO 4628-4
  • Casting / Scaling - ASTM D772, ISO 4628-5
  • Erosion - ASTM D662 Mold, Mold and Fungus - ASTM D3274
  • Dirt retention - ASTM D3274
  • Gray Scale - ASTM D2616, AATCC EP1
  • Adhesion - ASTM D3359
  • Corrosion - ASTM D610, ASTM D1654, ISO 4628-3 and -8
  • Filiform Corrosion - ASTM D2803, ISO 4628-10
  • TS 12552 Color measurement (colorimetry) DIN 5033-4: 1991 (NEQ) -; CIE 15.2 1986--; CIE 15.2: 1986--
  • Color Measurements according to TS EN Standards
  • TS EN ISO 2813 Paints and varnishes - Determination of non-metallic paint films at 20, 60 and 85 angles
  • TS EN 13523-2 Roll-coated metals- Test methods - Part 2: Brightness
  • TS EN 13745 Surfaces for sports fields - Determination of brightness reflection
  • TSE CEN / TR 16791 Determination of the amount of luminosity for the non-visual effects of light in humans
  • And other standards.

Color and Brightness Measurements

Instrumental measurements of appearance and surface properties include brightness, diversity of image and color. They are used in place of or in addition to visual ratings. Electro-optical measurements are required in many standards and provide data for statistical calculations.

The methods used in color measurement devices are two types: tristimulus method and spectrophotometric method. Red, green and blue (RGB: red, green, blue) are defined as three main colors. There are eye cells in the eye to detect these three colors. The devices measuring with the tristimulus method have x (λ), y (λ), z (λ) sensors instead of cells in the eye. The processor of the device converts the values ​​in this sensor to X, Y, Z tristimulus values. These values ​​are then converted to the selected method. In the spectrophotometric method, the visible region is measured with 360 nm pulses between 740-10 nm and converted from X, Y, Z tristimulus values ​​to the desired method with the processor of the device. Spectrophotometers can also measure spectral reflection at each wavelength or every wavelength range using multiple sensors, and then display the data on the spectral graph.

EUROLAB is capable of color measurement of interior and exterior trim parts with the most advanced spectrophotometers in the automotive and white goods sectors. Gloss measurements and paint adhesion tests are also experienced in EUROLAB.

  1. Color and Brightness Tests
  2. Painted Surface Measurement and Inspection
  3. Metallic Paint Color Measurements
  4. Solid Paint Color Measurements
  5. Brightness Measurement
  6. Paint Adhesion Test

The most popular and most popular color measurement method is L * a * b * method. It is one of the general color methods defined by the CIE in 1976 to reduce one of the major problems of the original Yxy color method. In this color range, L * indicates lightness / darkness and a * and b * are chromaticity coordinates. + a * direction is red, -a * direction is green, + b * direction is yellow and -b * direction is blue. The center is achromatic; As the a * and b * values ​​increase and move away from the center, the vividness of the color increases.

The word BRIGHTNESS can be defined as an optical feature that indicates how well a completely impermeable surface reflects light in a specular direction. Simply define; it can also be said as the ratio of the intensity of light reflected from the surface of an object to the intensity of light coming to the surface.

Brightness consists of a combination of the following 3 factor:

  • Refractive index of material
  • Angle of light arrival
  • Surface topography

The numerical value resulting from the gloss measurements in the world is expressed as the Gloss Unit (GU); It is a scale based on measuring the mirror reflection at a specified angle in a highly polished black glass in 100 GU units. The foundations of this terminology are based on standards established in German BAM, Canadian NRC and British NPL technology research centers.

Many different industries (paint, plastic, metal, paper, ceramics, furniture, textile, etc.) use 2813/523/20 ° geometries detailed in ISO60 and ASTM D85 standards for gloss measurements. However, apart from these angles, there are also 45 ° and 75 ° angle geometries, though not commonly used.

There are sectoral or international standards that are agreed upon by every industry, even every enterprise and its customers.