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Corrected haze measurement on metallic coatings
For non metallic surfaces, the diffuse component is lambertian- it is equal in amplitude
at all angles in relation to the sample surface. Conventional gloss-hazemeters measure
diffuse reflection using a luminosity sensor positioned away from the gloss angle.
Luminosity is subtracted from the haze signal allowing non metallic surfaces measured
independent of their colour.
Conventional gloss-haze meters do not work correctly on metallic coatings as metallic
flake within the coating reflects the light directionally around the specular angle. As little
or no metallic reflection is present at the angle at which the luminosity is measured,
metallic coatings and specialiy pigments have an unexpectedly high haze reading.
An advantage of the Novo-Gloss is that unlike a conventional instrument, compensation
is calculated using a region adjacent to the haze angle. This techniques gives
compatible readings on solid colours but also compensates for directional reflection
from metallic coatings and speciality pigments
Haze correction is only possible using haze measurement according to test method
ASTM E430, therefore when measuring bright or highly diffuse colours (metalics) a
difference will be noted between the two test methods. Measurements taken using
ASTM D4039 will be reported higher than ASTM E430 due to the diffusion from the
surface.
*This is option only available on the Novo-Gloss 20/60/85 with Haze
Light Source
Diode Array
Gloss
Metallic reflection
Haze
Metallic Coating
Incident Light
The Novo-Gloss captures compensation information from a region adjacent to the haze
measurement angle, this means it can be used on metallic coatings which reflect light
directionally
