A Preface
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ISO 6504-3-2019 – Determination of the hiding power of paints and varnishes – Part 3: Determination of the hiding power of masonry, concrete and interior paints

This document is prepared by Technical Committee ISO/TC 35, Paints and varnishes, Sub-Committee SC 9, General test methods for paints and varnishes.

The third edition eliminates and replaces the technically revised second edition (ISO 6504-3:2006). The main changes from the previous edition are as follows:

– The title and scope are limited to masonry and concrete coatings;

– Added the definition of light paint;

— Introduction of a new method applicable only to water-based coatings (Method C);

— The determination of mass per unit area of dry coating and the determination of actual spread rate have been deleted (ISO 3233-3 can be used instead);

– The reference to a fixed spread rate has been removed from the introduction, scope and test report (it was removed from the previous version of the program);

— Historical precision values for methods A and B have been removed from the specification section, and information on new inter-laboratory comparisons for Method C has been added to the informational annex, Annex A;

— Updated normative citation documents.

A list of all parts of the ISO 6504 series can be found on the ISO website.

ISO 6504-3-2019 – Determination of the hiding power of paints and varnishes – Part 3: Determination of the hiding power of masonry, concrete and interior paints

Introduction
When determining the hiding power of masonry and concrete coatings, there are two techniques that can be used for substrate preparation and measurement:

a) Apply to colorless transparent foil, and then place the coated foil on the black and white panels in turn;

b) Direct application to black and white charts.

The spread rate is important for determining the covering power ratio. The spread rate can be determined according to ISO 3233-3 or according to another simplified method described in the standard specified in EN 13300 applicable to interior wall and ceiling coatings.

Because different operators using the same pull-down device will obtain coatings with significantly different thicknesses, this document describes an absolute opacity determination method. Collaborative trials between expert groups from multiple countries/regions have shown that reproducible results can be obtained by interpolating between measurements at two or more nearby measured coating thickness and including the specified spread rate to determine the covering power corresponding to the accurately specified spread rate. Stakeholders may agree on a specified transmission rate.

These methods are based on the observation that the hiding power is approximately a linear function of the inverse of the spread rate over a limited range of coating thickness that also corresponds to normal application of white or light paint. Thus, it is possible to interpolate between the results obtained with coatings of different thicknesses either graphically or by calculation with satisfactory accuracy.

ISO 6504-3-2019 – Determination of the hiding power of paints and varnishes – Part 3: Determination of the hiding power of masonry, concrete and interior paints

1 Scope of application
This document specifies the method for determining the hiding power, white or light color tristimulus values Y and Y 10 greater than 25 paint coating applied to black and white charts or colorless transparent foil. In the latter case, the tristimulus values Y and Y 10 are measured on the black and white panels. Subsequently, the hiding power was calculated from these tristimulus values.

The document also provides for a simple method to calculate the diffusivity of coatings with low volatile matter content and low evaporation rates, such as interior wall and ceiling coatings specified in EN 13300.

2 Normative reference documents
When the following documents are referred to in the text, part or all of their contents constitute the requirements of this document. For dated references, only the cited version applies. For undated citations, the new version of the citation document (including any revisions) applies.

ISO 1513, Paints and varnishes — Inspection and preparation of test samples

ISO 2811 (all parts), paints and varnishes — Determination of density

ISO 3251, Paints, varnishments and plastics – Determination of the content of non-volatile substances

ISO 3233-3:2015, Paints and varnishes-determination of percentage of nonvolatile matter by volume – Part 3: Nonvolatile matter content, density of coating materials and density of solvents in coatings as determined in accordance with ISO 3251

ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling

EN 13300, Paints and varnishes – Water-based paints and coating systems for interior walls and ceilings – Classification

ISO 6504-3-2019 – Determination of the hiding power of paints and varnishes – Part 3: Determination of the hiding power of masonry, concrete and interior paints

3 Terms and definitions

For the purpose of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for standardization at the following addresses:

– ISO online browsing platform iso.org/obp

– IEC Electropedia: available at electropedia.org/

3.1 Light paint

Coatings with tristimulus values Y and Y 10 greater than 25 were measured with a spectrophotometer on a black and white substrate

[Source: ISO 6504-1:2019, 3.1]

3.2 Transmission rate

A certain amount of paint can cover the surface area to provide the desired thickness of the dry film

Note 1: Expressed as m 2 /l or m 2 /kg.

Entry note 2: See also application rate, actual spread rate, and theoretical spread rate.

[Source: ISO 4618:2014, 2.238]

3.3 Actual seeding rate

Actual spread rate obtained on the specific substrate to be coated (3.2)

[Source: ISO 4618:2014, 2.203]

3.4 Theoretical spread rate

Diffusivity based only on the volume of non-volatile matter (3.2)

[Source: ISO 4618:2014, 2.256]

ISO 6504-3-2019 – Determination of the hiding power of paints and varnishes – Part 3: Determination of the hiding power of masonry, concrete and interior paints

3.5 Hiding Power

The ability of a coating to eliminate the color or chromatic aberration of a substrate

Entry Note 1: The German expressions “Deckkraft” and “Deckfahigkeit” should be avoided.

Entry Note 2: The term “coverage” is ambiguous because it is used in some contexts to refer to coverability and in others to refer to transmission rate. More precise terms for covering power and spread rate should always be used.

[Source: ISO 4618:2014, 2.138]

3.6 Tristimulus value (color stimulus)

In a given three-color system, the number of the three reference stimuli needs to match the color of the stimulus under consideration

Note 1: In the CIE standard chrominance system, the tristimulus values are represented by the symbols X, Y, Z and X 10, Y 10, Z 10.

[Source: ISO 11664‑2:2007, 3.14]

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