Meaning and use

5.1 Coloring power may be a factor in determining the relative economic value of the paint, because the pigment concentration contributes to the strength to a large extent; Other factors are formulation and color development in grinding. Users can also select products with other properties with different shading strengths, such as transparency. The results of this test method can be used for production control or quality comparison.

5.2 For a particular artistic use, the product with the greatest or least coloring power may not be the most desirable. For example, low coloring intensity can result in the need to use too high a pigment concentration to get the desired color effect, which can lead to defects in the dry paint film.

5.3 This test method is only applicable to single pigment coatings. The coloring strength of coatings containing two or more color pigments with different optical properties cannot be assessed by this test method.

ASTM D4838-16 “Standard Test Method for Determination of Relative Coloring Power of Color Coatings”

5.4 The term “similar chemical type” as used in 1.1 does not restrict the composition in the paint, but rather refers to the compatibility of the vehicle and the similarity of the pigment type

5.5 Although instrumental assessment of tint strength is described, visual comparisons of lower precision can also be used and confirmation of instrumental and calculated results should be carried out.

5.6 If the sample and the standard differ greatly in appearance when prepared with the same proportion of color paint and white paint, another sample should be prepared so that the two are closer in appearance to obtain accurate results.

5.7 Whether by weight or volume, it is necessary to know exactly the amount of mixed color and white paint, but it is not necessary to know the concentration of pigments in the color paint.

ASTM D4838-16 “Standard Test Method for Determination of Relative Coloring Power of Color Coatings”

5.8 When the paints being compared have the same carrier and pigment (same color index name and number), the corrected color force values for the uncorrected color force strength 9.1 and 9.2 should be nearly the same. If not, it is recommended to take the average of the two shading forces as a good estimate of the true value, and the range provides a measure of uncertainty, which is due to differences in hue or chroma, or between the two. Paint.

5.9 Strictly speaking, the Kubelka-Munk type analysis of this test method should not be applied to the tri-stimulus filter readings used, but only to the spectral data. However, for the purpose of a relative comparison of this test method, the errors introduced by the calculations used are eliminated to an appropriate extent.

ASTM D4838-16 “Standard Test Method for Determination of Relative Coloring Power of Color Coatings”

Step 1: Scope

1.1 This test method describes the determination of the absorption coloring strength of a color test coating relative to a standard or reference coating of the same chemical type. The procedure is based on diluting the paint using standard mixed white paint and then performing instrumental measurements and calculations. Provides results for correcting slight differences in tone or chroma or both between test and reference color coatings.

1.2 This test method is used to compare coatings containing the same type of carrier (acrylic, alkyd or oil) and the same color index 2 name and number of single pigment colorants. It is not necessary to know the amount of pigment and other components of the paint.

1.3 Values expressed 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 and health practices and to determine the applicability of regulatory restrictions prior to use.