ISO 21025:2026

• Abstract:

  This document specifies the test method for evaluating the formaldehyde purification performance of interior wall coatings using the bag method. This document is applicable to the measurement and evaluation of formaldehyde purification performance of various types of interior wall coatings. This document can also apply to other indoor decoration materials with formaldehyde purification performance, such as wallpaper, carpets and decorative panels. Additionally, the method can be extended to the evaluation of the purification performance of other carbonyl compounds, such as acetaldehyde, propionaldehyde and butyraldehyde.

• Status: Published
• Publication Date: 02-Aug-2026
• ICS: 87.040 - Paints and varnishes
• Technical Committee: ISO/TC 35/SC 16 - Chemical analysis
• Drafting Committee: ISO/TC 35/SC 16 - Chemical analysis
• Current Stage: 6060 - International Standard published
• Start Date: 03-Aug-2026
• Due Date: 31-May-2026
• Completion Date: 03-Aug-2026

Overview

ISO 21025:2026, titled "Paints and varnishes - Assessment of formaldehyde purification effect of interior wall coatings by bag method," establishes a standardized test method for evaluating the formaldehyde purification performance of interior wall coatings. Developed by ISO, this international standard specifies the use of the bag method to measure how effectively coating products remove formaldehyde from indoor air. The method is not limited to wall paints and varnishes, but can also be applied to a wide range of interior decorative materials, including wallpaper, carpets, and decorative panels. Moreover, the standard can extend to testing the purification efficiency for other carbonyl compounds, such as acetaldehyde, propionaldehyde, and butyraldehyde.

Key Topics

• Test Method Using Bag Technique: The core procedure involves placing a coated specimen in a sealed, inert sampling bag, injecting a formaldehyde solution, and measuring changes in formaldehyde concentration over time.
• Initial and Long-Term Purification Performance: The standard distinguishes between initial purification efficiency (after first exposure) and long-term performance (after repeated exposures), essential for evaluating durable air purification.
• Versatility Across Materials: While focused on wall coatings, ISO 21025:2026 enables assessment of other indoor materials marketed for formaldehyde or carbonyl compound reduction.
• Systematic Sample Preparation: The document standardizes panel conditioning, solution preparation, and environmental control for consistent, repeatable results.
• Precision and Reproducibility: It provides procedures for validation, including interlaboratory testing statistics, ensuring reliability and comparability of results across different laboratories.

Applications

ISO 21025:2026 is highly relevant for manufacturers, testing laboratories, certification bodies, and regulatory agencies in the construction, interior decoration, and coatings industries. Its practical applications include:

• Product Development and Quality Control
  • Enables manufacturers to quantify and validate the air purification claims of interior wall paints, varnishes, wallpapers, carpets, and panels.
  • Assists in optimizing formulations to enhance VOC and formaldehyde removal efficiency.
• Third-Party Testing and Certification
  • Independent laboratories can deliver standardized assessments for product labeling, green building certifications, or compliance with air quality regulations.
• Market Differentiation
  • Suppliers can use ISO 21025:2026 results to demonstrate their products' performance, supporting marketing initiatives and meeting consumer demand for low-emission, healthier indoor environments.
• Specification and Procurement
  • Architects, designers, and facilities managers can require ISO 21025:2026 test results as part of material selection for environmentally conscious construction or renovation projects.
• Research and Regulation
  • Provides a consistent baseline for academic research and informs policy development related to indoor air quality and emissions from decorative materials.

Related Standards

Implementing or referencing ISO 21025:2026 may require familiarity with the following related international standards and test methods:

• ISO 1513: Paints and varnishes – Examination and preparation of test samples
• ISO 3696: Water for analytical laboratory use – Specification and test methods
• ISO 15528: Paints, varnishes and raw materials for paints and varnishes – Sampling
• ISO 16000-3: Indoor air – Determination of formaldehyde and other carbonyl compounds in indoor and test chamber air – Active sampling method
• ISO 16000-23: Indoor air – Performance test for evaluating reduction of formaldehyde and other carbonyl compounds concentrations by sorptive building materials
• ISO 22197-4: Fine ceramics – Test method for air-purification performance of semiconducting photocatalytic materials – Part 4: Removal of formaldehyde

These standards provide complementary procedures and definitions, helping ensure accuracy and harmonization across different evaluation methods in indoor air quality management.

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Keywords: ISO 21025:2026, formaldehyde purification, bag method, indoor wall coatings, air quality, carbonyl compounds, paints and varnishes standard, indoor air purification, assessment method, building materials testing, interior decoration materials.

International
Standard
ISO 21025
First edition
Paints and varnishes — Assessment
2026-08
of formaldehyde purification effect
of interior wall coatings by bag
method
Peintures et vernis — Évaluation de l’effet de purification du
formaldéhyde des revêtements muraux intérieurs par la méthode
du sac
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Reagents and materials . 2
7 Experimental system validation . 3
7.1 Test equipment .3
7.2 Cleaning of sampling bags .3
7.3 Measurement of natural reduction ratio of formaldehyde in sampling bag .4
8 Analysis of formaldehyde concentration . 4
9 Sampling . 4
10 Standard test conditions . 4
11 Test procedures . 4
11.1 General .4
11.2 Preparation and condition of specimen panel .5
11.3 Measurement of initial formaldehyde purification efficiency .5
11.4 Measurement of long-term formaldehyde purification efficiency .5
11.4.1 Specimen panel saturation test .5
11.4.2 Test on long-term formaldehyde purification efficiency .5
11.4.3 Determination of formaldehyde emission from specimen panel .6
12 Precision . 6
12.1 General .6
12.2 Repeatability limit, r . .6
12.3 Reproducibility limit, R .6
13 Test report . 6
Annex A (informative) Results of the interlaboratory test . 7
Bibliography . 9

iii
Foreword
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This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 21025:2026(en)
Paints and varnishes — Assessment of formaldehyde
purification effect of interior wall coatings by bag method
WARNING — The use of this document can involve hazardous materials, operations and equipment.
This document does not purport to address all of the safety problems associated with its use. It is
the responsibility of users of this document to take appropriate measures to ensure the safety and
health of personnel prior to the application of the document, and to determine the applicability of
any other restrictions for this purpose.
1 Scope
This document specifies the test method for evaluating the formaldehyde purification performance of
interior wall coatings using the bag method.
This document is applicable to the measurement and evaluation of formaldehyde purification performance
of various types of interior wall coatings.
This document can also apply to other indoor decoration materials with formaldehyde purification
performance, such as wallpaper, carpets and decorative panels. Additionally, the method can be extended
to the evaluation of the purification performance of other carbonyl compounds, such as acetaldehyde,
propionaldehyde and butyraldehyde.
2 Normative references
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 1513, Paints and varnishes — Examination and preparation of test samples
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
ISO 16000-3, Indoor air — Part 3: Determination of formaldehyde and other carbonyl compounds in indoor air
and test chamber air — Active sampling method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology 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
natural reduction ratio of formaldehyde in sampling bag
ratio of the reduced concentration of formaldehyde in the blank sampling bag to the initial concentration of
formaldehyde within a certain period of time

3.2
initial formaldehyde purification efficiency
ability of the coating test panel in the bag to purify formaldehyde after applying a single specified
concentration of formaldehyde, under the specified test conditions
3.3
long-term formaldehyde purification efficiency
ability of the coating test panel in the bag to maintain formaldehyde purification performance after repeated
application of formaldehyde at a specified concentration, under the specified test conditions
4 Principle
The specimen panel is prepared according to the theoretical application amount and application method
provided by the coatings product manufacturer.
Then the specimen panel is conditioned under standard test conditions for a specific period of time and put in
a sampling bag. A certain amount of formaldehyde solution is injected, or a certain amount of formaldehyde
solution is injected several times until certain saturation state has been reached.
The change of formaldehyde concentration in the bag within a specific period of time is analysed, and the
initial formaldehyde purification efficiency and long-term formaldehyde purification efficiency of the sample
are calculated.
5 Apparatus
5.1 Sampling bag, with the following characteristics:
— material and capacity: the sampling bag material shall be inert, impermeable, and non-sorbing [e.g.
fluorinated resins, such as poly (vinyl fluoride) (PVF) or fluoroethylene/fluoropropylene copolymer
(FEP) plastic]. The bag capacity shall be at least 50 l.
— airtightness: sampling bags shall be sealed securely with low-emitting tape or sealing strip or heat
bonded so as to be isolated from the uncontrolled ambient air.
— background concentration: the background concentration shall be as low as possible (e.g. below 7,5 µg/
m for formaldehyde) so that it does not interfere with the test results.
5.2 Micro syringe, with a volume of 10 μl and division value of 0,2 μl.
5.3 Sampling pump, which shall meet the requirements of ISO 16000-3. The flow shall be stable during
the sampling process. The flow range shall be 0 ml/min to 1 200 ml/min, and the flow fluctuation shall not
exceed ± 5 % of the sampling flow. Gas flow meters should be regularly used to calibrate the sampling pump.
5.4 Gas mass flow controller for filling the sampling bag with carrier gas. The response time should be
less than 100 ms and the repeatability should be ≤ 0,1 % (full scale). Gas flow meters should be regularly
used to calibrate gas mass flow controllers.
5.5 Vacuum pump, empty the gas in the sampling bag quickly.
...