المعنى والغرض
5.1 The contrast at the specified film thickness is a useful hiding power parameter for production control and procurement specifications.

5.2 The greater the hiding power, the less paint is required per unit area to obtain sufficient hiding power. لذلك, knowledge of hiding power is important for coating costs and comparing coating values.

أستم د 6441-1999 طريقة الاختبار القياسية لتحديد قوة إخفاء مسحوق الطلاء

نطاق
1.1 These test methods determine and report the hiding power of powder coatings based on two parameters:

1.1.1 طريقة الاختبار أ — Contrast at a given film thickness

1.1.2 طريقة الاختبار ب — Film thickness at 0.98 (98%) contrast.

ملحوظة 1: The measurement parameters follow powder coating industry practice by measuring the hiding power with respect to film thickness, rather than the “spread rate” function used in test methods D344 and D2805 and other hiding power test methods.

ملحوظة 2: Hiding power is defined in luminosity as spread rate at 0.98 contrast. Please refer to terms D16, D2805 and the definitions of diffusivity and hiding power in the Paints and Coatings Testing Manual.

ملحوظة 3: A contrast ratio of 0.98 is generally accepted by the paint industry as “full” coverage for reflective coverage measurements. But visually and photologically, it is still slightly incomplete.

أستم د 6441-1999 طريقة الاختبار القياسية لتحديد قوة إخفاء مسحوق الطلاء

1.2 These test methods include determination of the hiding power of electrostatic sprayed powder coatings.

1.3 These test methods determine the hiding power by measuring with reflectometer and thickness gauge. They are restricted to coatings with a minimum CIE-Y reflectivity of 15%.

1.4 Values expressed in SI units should be considered standard. القيم الواردة بين قوسين هي للإشارة فقط.

1.5 ليس المقصود من هذا المعيار معالجة جميع قضايا السلامة, لو اي, المرتبطة باستخدامه. It is the responsibility of users of this standard to establish appropriate safety and health practices and to pre-determine the applicability of regulatory restrictions prior to use.