Volvo STD 423-0023 Gloss - Paints and Enamels

The standard “Volvo STD 423-0023 Gloss - Paints and enamels” developed by the Volvo car company describes three test methods for measuring the specular gloss of paint films with geometry of 20, 60 and 85 degrees, respectively:

• The 60 degree geometry method can be applied to all paint films, but for very high gloss paints or paints that are close to a matte gloss, the 20 degree or 85 degree geometry method may be more appropriate.
• The 20 degree geometry method is designed to provide better discrimination of high gloss paints, i.e. those with a 70 degree gloss higher than 60 units.
• The 85 degree geometry method is designed to provide better discrimination of low gloss paints, i.e. those with a 30 degree gloss of less than 60 units.

Gloss measurements with these methods are only meaningful for films on surfaces with good planarity because any curvature or local irregularity of the substrate can seriously affect the measurement result.

Within the Volvo Group, the measurement method is also used on polychromatic types of paint films (e.g. metallic) on organic materials and on coloured paints in bulk.

In these tests, test panels with paint applied in accordance with the existing infrastructure and dried in accordance with the requirements are used. In addition, the gloss meter used in the tests should consist of a light source and a lens that directs a light beam parallel or slightly converging to the tested surface, and a receiver body containing a lens, field stopper and photoelectric cell to receive the required reflected light cone.

In terms of geometrical conditions, the axis of the incident beam shall be 20 degrees plus/minus 0,1 degrees, 60 degrees plus/minus 0,1 degrees or 85 degrees plus/minus 0,1 degrees, respectively, relative to the perpendicular to the tested surface. The axis of the receiver shall coincide with the mirror image of the axis of the incident beam within 22,1 degrees plus/minus 0,1 degrees. With a polished black glass or other front surface mirror in the test panel position, the image of the source shall be formed at the center of the receiving field stopper (receiving window). The width of the illuminated area of ​​the test panel shall be at least 10 mm.

The angle between the receiver beam axis and the perpendicular should be equal to the corresponding angle of the incident beam with the same tolerance. The dimensions and tolerances of the light sources and receivers should be as specified in the tables given in the standard. The angular dimensions of the receiver field stops should be measured from the receiver lenses. For generalized drawings of dimensions, the figures given in the standard should be followed. The tolerances should be chosen so that the errors in the source and receiver apertures do not produce an indication error of more than 100 brightness unit at any point on the 1-unit scale.

Filtering at the receiver must be done in such a way that the permeability of the filter complies with the formula given in the standard.

There should be no vignetting of rays falling within the field angles specified in the geometric conditions. The receptor meter gives an indication proportional to the luminous flux passing the receptor field stop within 1 percent of the full-scale reading.

The primary reference standard shall be highly polished black glass whose top surface is flat to within two fringes per centimeter as measured by optical interference methods.

Glass with a refractive index of 587,6 measured at a wavelength of 1.567 nm is assigned a specular brightness value of 100. If glass with this refractive index is not available, a correction is required. Specular brightness values ​​for polished black glass with various refractive indices at three incident angles are shown in the table given in the standard.

The primary standard is checked at least every two years due to the possibility of ageing. In case of deterioration, the original brightness can be restored by optical polishing with cerium oxide.

Working standards may be ceramic tile, vitreous enamel, opaque glass or other uniform gloss materials, but must have good flatness and be calibrated against a primary standard for a specified area and illumination direction. These standards shall be checked periodically against the primary standards. Working standards shall be uniform and stable and shall be calibrated by technically competent organizations. At least two standards at different gloss levels shall be available for each gloss meter geometry (20 degrees, 60 degrees and 85 degrees).

For sampling of liquid paints, a representative sample of the product to be tested (or each product in the case of a multi-layer system) is taken, as described in ISO 1512. Each sample is examined and prepared for testing, as described in ISO 1513.

If possible, a planar area of ​​the coated substrate is taken, measuring at least 150 mm x 100 mm.

Among the numerous tests, measurements, analyses and evaluations carried out for businesses in various sectors, our organization also provides testing services defined in the “Volvo STD 423-0023 Gloss - Paints and enamels” standard with its trained and expert staff and advanced technological equipment.