ASTM D4039-93(2004)

Measured gloss values of specimens depend on the angle of illumination, refractive index of the material, and the geometric distribution of the reflected light.

Haze is produced by irregularities in the reflecting surface that affect the distribution of flux reflected around the specular angle. The procedures specified in Test Method D 523 are not designed to measure reflected-flux scattering characteristics of high-gloss finishes, particularly where specimens having different surface refractive indexes are being compared. A better index of scattering can be obtained by making two specular reflectance measurements, that is, the use of two receptor apertures of different size.

In this test method, values for reflection haze are obtained from two measurements of specular gloss, one made with a large receptor aperture and the other made with a small receptor aperture. The geometric conditions have been chosen to permit the use of glossmeters that provide 60° specular gloss measurements (large receptor aperture) and 20° specular gloss measurements (small receptor aperture) as specified in Test Method D 523.

An additional method for the measurement of reflection haze is given in Test Method E 430.

1.1 This test method describes a procedure for using two specular gloss measurements to obtain a haze index for high-gloss nonmetallic specimens (). It is particularly useful for evaluating the haze in clear finishes on nonglossy substrates, and the haze in reflected images produced by the surfaces of opaque glossy pigmented finishes.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.