Meaning and use
3.1 When the coating is applied to a large surface such as a wall, the film thickness may vary when the color of the fresh material is very similar to the previous film, or small areas may be completely missed (holidays). If these areas could be retouched without having to repaint the entire surface, the cost would be much lower.

3.2 Where the area that was coated a short time ago is connected to the area that is currently coated (number of turns), the thickness is also affected. An application technique that may affect the final appearance of the film is brushing or rolling the material in different directions in adjacent areas.

3.3 Both buyers and sellers are interested in determining whether the coating can be applied without areas showing differences in appearance due to lap and brush or roller markings, and whether it can be easily modified to provide a uniform appearance in gloss or shine and all other aspects.

ASTM D3928-2018 Standard Test Method for Evaluating Gloss or Luster Uniformity

Radius
1.1 The test method includes determining the gloss or uniformity of the gloss of the paint applied by brush to a test panel that simulates an interior wall portion. Visually assess changes in shine or gloss that may be caused by short wet edge time, poor leveling, and pigment orientation or flotation during and after application.

1.2 As both application and group assessment are very subjective, this test method should only be used for comparative testing in one laboratory, as ratings assigned by different laboratories are often inconsistent (see 8.1).

1.3 Values given in SI units shall be considered standard. The values given in parentheses are for reference only.

1.4 This standard is not intended to address all safety concerns, if any, associated with its use. It is the responsibility of users of this standard to establish appropriate safety, health and environmental practices and to determine the applicability of regulatory restrictions prior to use.

1.5 This international standard is based on internationally recognized standardization principles established in the Decision on Principles for the Development of International Standards, Guidelines and Recommendations issued by the WTO Committee on Technical Barriers to Trade.