Betekenis en gebruik

5.1 Due to poor compatibility, the colorant is sometimes not fully dispersed in the base paint, which may be a disadvantage of the colorant, the paint or both. This will result in poor color rendering, which is easily demonstrated by the conventional method of applying paint with a scraper and rubbing small areas of partially dried film through your fingers so that scraping produces high shear stress. This tends to disperse the undeveloped colorant (indien aanwezig) and create a color change between the uncut and cut areas of the paint film. The change can be measured by comparison to give a numerical color difference value, which is a measure of the color development of the original paint, the smaller the difference, the better the color rendering, en vice versa. It is found that the color difference obtained by finger friction varies greatly for the same and different operators. This test method establishes a controlled shear stress procedure similar to a finger wipe test, but with better reproducibility.

5.2 Poor color development may be a problem in paint production, or it may be a problem in oilfield production. In production, it can lead to a loss of the monetary value of the colorant, as well as unpredictable coloring results. In field performance, changes in the color of the applied film result from varying shear forces that the paint is subjected to at different stages or through different modes of application.

ASTM D5326-0 “Standard Test Method for Color Development in Colored Latex Paints”

5.3 While poor color rendering is primarily and usually associated with the colorant portion of tinted coatings, white pigments in base coatings can also be poor due to flocculation or other reasons. In the latter case, shear dispersion can make the paint film lighter and less colorful, rather than the other way around. Dan, the colorant and white may also both be poor, and the color change caused by shear stress will be a combined effect of both.

5.4 In any case, color rendering is an important coating property, and for measurement, this test method is intended to provide a generally accepted and repeatable test method.

Stap 1: Domein

1.1 This test method includes procedures for measuring color development in tinted latex paints with the aim of determining the efficiency of the colorant, the tint of the base paint and the likelihood of poor color uniformity of the painted film.

1.2 Waarden in inches tot ponden worden als standaardwaarden beschouwd. De waarden tussen haakjes zijn wiskundige transformaties van SI-eenheden en dienen alleen ter referentie en worden niet als standaard beschouwd.

1.3 Deze norm is niet bedoeld om alle veiligheidsproblemen aan te pakken, indien aanwezig, die verband houden met het gebruik ervan. Het is de verantwoordelijkheid van gebruikers van deze norm om passende veiligheids- en gezondheidspraktijken vast te stellen en voorafgaand aan gebruik de toepasbaarheid van wettelijke beperkingen te bepalen..