What is RSpec?
RSpec is the peak reflectance measured over a very narrow angular band in the specular direction (+/-) 0.0991ยบ.
RSpec is very sensitive to any texture that is present on a surface. This texture or waviness acts as a concave or convex reflector that deflects light around the specular angle. When RSpec is equal to the gloss value the surface is smooth, as texture increases the RSpec value decreases.
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The diagram above shows the same coating applied to two panels, the first has orange peel/waviness present due to the incorrect application setting on the spray gun.