ISO/DIS 25146:2025(en)

ISO/TC 328/ WG 4

Secretariat:UNI

Date:2025-06-11

Determination of the chemical resistance of engineered stones

© ISO 2025

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Contents

Foreword iv

Introduction v

1 Scope 1

2 Normative references 1

3 Terms and definitions 1

4 Principle 2

5 Materials 2

5.1 Chemical test solutions and reflection test 2

5.1.1 Weak household chemicals 2

5.1.2 Acids and alkalis with low concentrations (L) 2

5.1.3 Acids and alkalis with high concentrations (H) 3

5.2 Apparatus 3

5.2.1 Cylindrical ring of borosilicate glass or any other suitably chemical resistant material, having an opening for filling and a lid to prevent loss of the test solution. 3

5.2.2 Suitable solvent, distilled water and alcohol Error! Bookmark not defined.

5.2.3 Soft cellulose paper, white cloth composed of cotton or flax, or any other suitable cloth for use in laboratory applications requiring absorbent materials. 3

5.2.4 A glossmeter is used to measure the brightness of a surface with an accuracy of 10%. Error! Bookmark not defined.

6 Test specimens 4

6.1 Number of test specimens 4

6.2 Preparation of the specimens 4

7 Test procedure 4

7.1 Application of reflection test 4

7.1.1 results for reflection classification 5

7.2 Application of solutions test 6

7.2.1 results for solution in acids and alkalis classification 7

8 Test report 7

Annex A (formative) Test Report Table 9

A.1 Test report table 9

Bibliography 11

Foreword

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This document was prepared by Technical Committee ISO/TC 328, Engineered stones.

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Introduction

This standard will be developed following international practices and informed by available research where applicable.

The justification for this project is twofold. First, it will ensure that engineered stone products meet the highest safety and quality standards. Second, it will promote the responsible consumption and production of these products, supporting the achievement of the SDGs. It will further contribute to the achievement of the United Nations Sustainable Development Goals (SDGs), Specifically, will contribute to the following SDGs: Goal 8 (Decent Work and Economic Growth), Goal 9 (Industry, Innovation, and Infrastructure), Goal 12 (Responsible Consumption and Production), Goal 13, and Goal 17 (Partnerships for the Goals).

ISO standard of Engineered stone - Determination of chemical resistance specifies a test method for evaluating the chemical resistance of engineered stone products. It provides a consistent procedure for assessing surface durability under exposure to common household and industrial chemicals, supporting quality control and material comparison across manufacturers and applications.

Determination of chemical resistance of engineered stones

This document specifies for determining the chemical resistance of engineered stone with resin and cement binders or combinations used in countertops and vanities (furniture in general), floor and wall coverings, and interior and exterior (constructions in general).

To find any change in color and appearance, two tests are specified for determining the chemical durability of engineered stones under controlled conditions at normal room temperature, that considered to be 23 °C ± 2 °C. The tests are appropriate for all varieties of engineered stones that possess a polished surface and may come into contact with chemical substances for an extended period of time.

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO/CD 25146, Determination of the chemical resistance of engineered stones

ISO 10545‑13, Ceramic tiles — Part 13: Determination of chemical resistance

EN 14617‑10, agglomerated stone - Test methods - Part 10: Determination of chemical resistance

For the purposes of this document, the following terms and definitions apply. For additional terms not defined in this document, reference should be found in ISO/CD 19947.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

3.1

aggregates

small mass of rock, having occurred naturally (as in sand or gravel) or by means of manufacture (as in a crushed aggregate product), used either in a loose, noncohesive state, or as, for example, an ingredient in mortar or concrete products

3.2

engineered stone

Composite material manufactured from a mixture of aggregates, binders and additives intended for fabrication of countertops and vanities, floor and wall coverings and ancillary uses, for both interior and/or exterior applications

Note 1 to entry: Engineered stone has also been known as artificial marble, artificial stone, manufactured stone, agglomerated stone, engineered quartz, quartz, quartz surfacing etc.

3.3

polished surface

surface of engineered stone that has been mechanically finished during the final stages of manufacturing to produce a polished, semi-polished, smooth, honed, lappato, or comparable appearance

[SOURCE: ISO 13006:2018(en), 3.5 modified]

3.4

solvent

liquid or mixture of liquids that is used to dissolve a substance or to dilute a solution without causing any chemical change

[SOURCE: ISO 472:2013(en), 2.1550]

3.5

unpolished surface

A surface having a thickness of roughness of about half of the average grain size

Engineered stones can react with chemically aggressive substances upon contact, resulting in corrosion, permanent penetration, or changes in appearance. Testing involves subjecting test specimens to specific test solutions to the extent of the attack after a predetermined period. Evaluation shall include both visual inspection and instrumental measurements to determine changes in appearance and quantify the loss of surface reflection.

The selection and preparation of test solutions in this document are informed by existing standards such as ISO 10545-13 and EN 14617-10, with modifications to accommodate the characteristics and use cases of engineered stones.

a) Ammonium chloride solution, 100 g/l.

Note 1 to entry: Concentrations expressed in g/L refer to mass of solute (in grams) dissolved in distilled water to make a final volume of 1 litre of solution.

b) Sodium hydroxide in a 50 % (V/V) water solution.

Note 2 to entry: Sodium hydroxide in a 50 % (V/V) water solution, prepared by adding 100 mL of distilled water to 4 g of reagent grade sodium hydroxide (NaOH) and stirring until solution is complete.

a) Hydrochloric acid solution, 3 % (V/V), prepared from concentrated hydrochloric acid (ρ = 1,19 g/ml).

b) Citric acid solution, 100 g/l.

c) Potassium hydroxide solution, 30 g/l.

a) Hydrochloric acid solution, 18 % (V/V), prepared from concentrated hydrochloric acid (ρ = 1,19 g/ml).

b) Potassium hydroxide solution, 100 g/l.

c) Lactic acid solution, 5 % (V/V) prepared from 85 % lactic acid.

Note 1 to entry: Engineered stones containing calcium carbonate aggregates and/or cement-based components are vulnerable to acid attacks, so it is essential to avoid testing them in acids and alkalis with high concentrations.

Note 2 to entry: If engineered stones containing calcium carbonate aggregates and/or cement-based components are not tested for acid resistance, this shall be clearly indicated in the test report. The test solutions listed in this clause shall be noted as not applicable to such materials.

Note 3 to entry: Engineered stones containing polyester resin are vulnerable to alkaline solutions, particularly high concentrations such as potassium hydroxide. Therefore, such tests should be avoided, and this shall be clearly indicated in the test report, with the corresponding test solutions noted as not applicable.

To assess resistance to organic solvents, specimens shall be tested using one solvent selected from the following list: acetone, ethanol (96 % v/v), white spirit (mineral turpentine), toluene, or isopropyl alcohol, depending on the intended application of the product.

Cylindrical retaining ring of borosilicate glass or any other suitably chemical resistant material, having an internal diameter sufficient to hold the specified test volume (see 7.1), with an opening for filling and a lid to prevent loss of the test solution.

To obtain a clean surface, when preparing specimens, it is crucial to use the appropriate solvent like distilled water, to clean and remove any substances before and after the preparation process.

Note 1 to entry: Avoid using other chemical solutions, as they may cause surface defects and chemical damage to certain engineered stones that contain calcium carbonate aggregates, cement-based, and specific resins.

Soft cellulose paper, white cloth composed of cotton or flax, or any other suitable cloth for use in laboratory applications requiring absorbent materials.

A glossmeter assesses how much light is specularly reflected off the surface compared to a standard glass plate. The measurement by a glossmeter with an accuracy of 10 % is conducted using natural daylight or any light source that simulates average daylight conditions. Equipped with two optical systems at 60° and 20° angles, the glossmeter effectively captures a wide range of reflection levels, with the 60° angle suitable for low to high reflections and the 20° angle providing enhanced accuracy for higher reflections.

A suitable, chemically resistant adhesive or sealing material shall be used to secure the cylindrical ring to the specimen surface. The material must not interfere with the test solution or alter the specimen’s surface.

Test specimens shall be representative of the sample; where the stone has different colours or decorative effects within its surface, care should be taken to include all such distinctive features in the areas that will be tested, and observations related to localized effects should be recorded in the Optional Notes section of the test report table (Annex A.1).

For each type of material to be tested, four samples shall be prepared with at least 300 mm × 300 mm. A cylindrical ring shall be placed onto the surface of each specimen and sealed using a suitable adhesive or sealing material.

The surface to be measured shall already possess a polished surface as defined in Clause 3.3, to allow proper positioning of the instrument sensor during testing. Before testing, the surface shall be cleaned of any possible wax, other finishes, or treatment layers using cotton (5.2.3) or a suitable solvent (5.2.2).

Each test’s design specifically covers engineered stone types that may or may not exhibit changes in reflection when exposed to chemicals.

Evaluation of chemical resistance is based on both changes in reflection and visible changes in color or appearance in two approaches:

A reflection test, using a glossmeter to measure changes in surface gloss (see 7.1), and

A visual solution test requires a visual examination relying solely on the naked eye to detect any differences in color and appearance (see 7.2).

In this procedure, the glossmeter sensor is placed in contact with the surface to be measured. The glossmeter shall comply with the requirements specified in Clause 5.2.4, including appropriate geometry selection and light source.

Use the 60° geometry as the standard measurement angle for most surfaces.

Use the 20° geometry only for very high-gloss surfaces where enhanced sensitivity is required.

Note 1 to entry: If the specimen shows very low gloss and does not produce measurable reflection values, the reflection test may be omitted, noted as not applicable in the test report, and only the visual solution test results shall be considered.

The number displayed on the glossmeter defines the reflection degree of the surface. Record this value in the corresponding section of the Test Report Table (See Annex A.1). This value is a reference for any changes that may occur after conducting the procedure. It is necessary to measure the reflection of at least five different points on each of the four specimens.

Place each specimen horizontally on a table covered with polyethylene film for protection, and place a cylindrical retaining ring onto its surface. Carefully add 10 to 15 ml of hydrochloric acid solution into two of the rings and sodium hydroxide solution into the other two, ensuring there is no overflow. After this step, repeat the process for the other two specimens using the sodium hydroxide solution. Do not remove specimens from the polyethylene film for the duration of the test procedure.

After approximately 1 hour ± 5 minutes, remove one specimen from hydrochloric acid and one from sodium hydroxide; discard the solutions. Remove the sealing ring. Wash each specimen carefully with water to remove all sealing materials. Specimens must be dried using soft cellulose. After an exposure period of 8 hours ± 30 minutes, remove the two remaining specimens and repeat the washing and drying process. This duration is based on EN 14617-10 and is used to assess the loss of surface reflection following chemical exposure.

Note 2 to entry: It is advisable to consider existing industry studies that examine the effect of exposure time on various stone types, as an alternative approach could include exposure times of 6 or 16 hours.

Repeat the same reflection measurements at five points per specimen. Calculate the average and standard deviation as defined in Clause 7.1.1 and record in the Test Report Table.

Chemical attacks are assessed based on the percentage loss of reflection, determined by comparing reflection values measured before and after chemical exposure. For this purpose, reflection values shall be recorded at five different points on each specimen and used to calculate the average reflection and standard deviation both prior to and following exposure.

Average Reflection Value (RVa)

The average reflection value shall be calculated using the formula:

where:

RVa is the average reflection value,

Ri is the individual reflection measurement at point i

n is the total number of measurement points (typically n=5).

Standard Deviation (σ)

The standard deviation of the reflection values shall be calculated using the formula:

where:

σ is the standard deviation of the reflection values,

Ra is the average reflection value as calculated above,

Ri is the individual reflection measurement at point i,

n is the number of measurement points.

Percentage Loss of Reflection

The percentage loss in reflection due to chemical exposure shall be calculated as:

where:

L is the percentage loss of reflection,

is the average reflection value before exposure,

is the average reflection value after exposure.

A class of resistance to acids and alkalis shall be attributed as follows. Record the classification in the corresponding section of the Test Report Table.

CR4: materials, which keep at least 80 % of the reflection reference value after 8 h ± 30 min of acid and basic attack (or if only in one of four specimen the attack is between 60 % and 80 %);

CR3: materials, which keep between 60 % and 80 % of the reflection reference value after 8 h ± 30 min of acid and basic attack;

CR2: materials, which keep less than 60 % of the reflection reference value after 8 h ± 30 min of acid and basic attack;

CR1: materials, which keep less than 60 % of the reflection reference values after 1 h ± 30 min of basic and acid attack.

The visual evaluation method is adapted from ISO 10545-13 and uses surface exposure rather than full immersion. Apply 5–10 ml of each test solution to the surface of the specimen using a chemically inert ring or a saturated absorbent pad. Ensure that the solution remains in contact with the surface without running or evaporating.

Evaluate the surface appearance after 1 hour ± 5 minutes and again after 24 hours ± 15 minutes. Record any visible changes, such as staining, discoloration, gloss loss, or texture alteration.

After each exposure period, gently remove the test solution using a soft, absorbent material, and rinse the surface with distilled water to eliminate any residual chemicals and dry the specimen using a clean cloth.

The 24-hour result shall be considered the primary indicator for classification. The 1-hour result may serve as an early indicator of surface sensitivity. Any additional observations may be included in the Optional Notes section of the test report, if relevant.

Visual comparison shall be made between the tested area and a reference sample of the same material that has not been subjected to chemical exposure under the same lighting conditions. Examine the surface tested from all angles from a standard distance of 25 cm, with the naked eye or with spectacles if usually worn, for any difference in appearance in gloss, color, or surface texture. Daylight or artificial illumination is permitted (approximately 300 Ix), but direct sunlight shall be avoided. After examination, use the following classification:

a) For test solutions listed in 5.1.1

CGa: No visible effect

CGb: slight change in appearance

CGc: Definite change in appearance

CGd: Partial or complete loss of the original surface appearance

b) For test solutions listed in 5.1.2

CGLa: No visible effect

CGLb: slight change in appearance

CGLc: Definite change in appearance

CGLd: Partial or complete loss of the original surface appearance

c) For test solutions listed in 5.1.3

CGHa: No visible effect

CGHb: slight change in appearance

CGHc: Definite change in appearance

CGHd: Partial or complete loss of the original surface appearance

The test report shall include/contain the following information:

a) unique identification number of the report;

b) reference to this part of this standard;

c) the test solutions and materials used;

d) name and address of the test laboratory and the address where the test was carried out if different from the test laboratory;

e) name and address of the client;

f) it is the responsibility of the client to supply the following information:

— name of the supplier;

— name of the person or organization that carried out the sampling;

— type of the binders (resin or cement binders or combination);

g) date of delivery of the sample or of the specimens;

h) the date when the specimens were prepared (if relevant) and the date of testing;

i) number of specimens in the sample;

j) dimensions of the specimens;

k) type of glossmeter used, the light source, and the reflection directions of the light;

l) results obtained in Test Report Table (See Annex A.1), including gloss values before and after testing, visual classifications, and computed classifications based on reflection loss.

1. 
   (informative)
   
   Test Report Table
   1. Test report table

Table A.1 — Test report result

Bibliography

[1] ISO 13006:2018, Ceramic tiles — Definitions, classification, characteristics and marking

[2] ISO 472:2013, Plastics — Vocabulary