Gloss is an important attribute of
surface appearance, it changes our perception of colours and influences our overall visual experience.
Gloss affects objects by the interaction
of incident light with the surface and observer and depends on variables such
as illumination angle, surface profile, physical characteristics and
observation conditions.
For many products, gloss can play an
important part in their visual acceptability and for quality purposes should be
monitored with precision instrumentation particularly when it varies through
the Gloss is an aspect of the visual perception of objects that is as important
as colour when considering the psychological impact of products on a consumer.
In other words, "Gloss Sells" Gloss has been defined as the attribute
of a surfaces that causes it to have a shiny or lustrous, metallic appearance.
The gloss of a surface can be greatly
influenced by a number of factors, for example the smoothness achieved during
polishing, the amount and type of coating applied or the quality of the
substrate
Gloss is measured by shining a known
amount of light at a surface and quantifying the reflectance. The angle of the
light and the method by which the reflectance is measured are determined by the
surface.
The Rhopoint IQ is a
precision instrument that measures gloss using the following parameters in a
single button push: 20/60/85° Gloss, Haze, Reflected Image Quality (RIQ), Distinctness
of Image (DOI)
Gloss is a measurement proportional to
the amount of light reflected from a surface measured at 20° (high gloss
finishes) 60° ( mid gloss finishes ) and 85° ( matt finishes) Haze: Reflection
haze is scattered light caused by micro texture and is measured adjacent to the
main gloss component. The gloss value is determined by directing a light, which
has a similar wavelength to the human eye, at a specific angle to the test
surface and measuring the amount of specular reflection.
The optics is set in an aluminium block
giving optical bench accuracy and stability. To ensure international standard
compliance, the light source is supplied from long-life tungsten halogen lamps.
Place the gloss meter on the surface to be measured, press the required angle
button and the gloss reading will appear on the display. This reading will be
held until another reading is taken.
Trade practice recognizes the following
gloss levels, in increasing order of gloss: flat (or matte) practically free
from sheen, even when viewed from oblique angles (usually less than 15 on
60-degree meter); eggshell- usually 20-35 on 60-degree meter;
semi-gloss-usually 35-70 on 60-degree meter; full-gloss-smooth and almost
mirror-like surface when viewed from all angles, usually above 70 on 60-degree
meter.
The instrument will automatically switch
off when not in use. Easy to read two-line alphanumeric display with back
lighting, powered by internal rechargeable batteries, battery voltage can be
checked on the display. Rhopoint IQ (Gonio photometer) 20°/60°/85°-
http://www.rhopointinstruments.com/.../rhopoint-iq.../
Articles
Paint Surface -
Light Reflection - TOGWT
Bibliography
1.
Gloss as an aspect of the measurement of appearance by W Ji, MR
Pointer, RM Luo, J Dakin
2.
Surface correlation effects on gloss by R Alexander-Katz, RG
Barrera - Journal of Polymer Science
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