🧵 pH of the aqueous extract of textiles — extraction of two specimens of (2,00 ± 0,05) g in 100 ml of 0,1 mol/l potassium chloride solution for 2 h, measurement with a glass electrode, mean of two results to the nearest 0,1 pH; PN-EN ISO 3071

Materials and NDT PN-EN ISO 3071

Overview

WHAT THE STANDARD COVERS. ISO 3071:2020 (clause 1) specifies a method for determining the pH of the aqueous extract of textiles; the method is applicable to textiles in any form (e.g. fibres, yarns, fabrics). According to the introduction, the pH of the aqueous extract is a useful index of the processing history of a textile, and it is increasingly required that the textile conform to certain limits of acidity or alkalinity, often expressed as the pH of the extract. Definition (3.1): pH is the co-logarithm of the hydrogen ion concentration in the aqueous extract. Principle (clause 4): the pH of the extract is measured electrometrically at room temperature by means of a glass electrode. We read the text of the standard in the iTeh sample of ISO 3071:2020 (English and French text): from the title page through the foreword, introduction and clauses 1–11 up to and including the test report; outside the sample remain informative Annex A (preparation of buffers) and the bibliography.

REAGENTS AND APPARATUS (clauses 5–6). Reagents of recognized analytical grade. Distilled or deionized water of at least grade 3 according to ISO 3696, with a pH between 5,0 and 7,5 — the pH of the water is checked the first time it is used; outside this range the water is redistilled in chemically resistant glassware (acid and organic matter are removed by distilling from a solution of 1 g/l potassium permanganate and 4 g/l sodium hydroxide, alkalinity — e.g. ammonia — by distilling from dilute sulfuric acid); distilled water that is not grade 3 is boiled in a beaker (100 ml) at a moderate rate for (10 ± 1) min and cooled covered. Extracting solution: 0,1 mol/l potassium chloride made up with this water. Buffer solutions with a pH similar to that being determined — prepared according to Annex A or obtained commercially; buffers of about pH 4, 7 or 9 are recommended. Apparatus: stoppered glass or polypropylene flasks, chemically resistant (it is recommended to set them aside for this test only); a mechanical shaker ensuring exchange of liquid between the interior of the material and the solution — a to-and-fro movement of 60 cycles/min or a rotational frequency of 30 r/min has been found satisfactory; 150 ml beakers; rods; a pH meter with a glass electrode with a resolution of at least 0,01 pH (temperature compensation is recommended); a balance with a resolution of at least 0,01 g; 1 l volumetric flasks of grade A.

SPECIMENS AND EXTRACT (clause 7, 8.1). From a laboratory sample representative of the bulk of the material, pieces with sides of about 5 mm, or of a size allowing rapid wetting, are cut; the material is handled as little as possible. Two test specimens of (2,00 ± 0,05) g each are taken. Each specimen is placed with 100 ml of potassium chloride solution in a stoppered flask, shaken briefly by hand to wet the material, and shaken mechanically for 2 h ± 5 min at room temperature.

MEASUREMENT (8.2). The temperature of the extracting solution is recorded. The pH meter is calibrated according to the manufacturer's instructions at the temperature of the extract to be measured, and the calibration is checked with two buffers. The electrode is immersed several times in the potassium chloride solution used for the extraction until the reading stabilizes. A portion of the first extract is decanted into a beaker, the electrode is immersed to a depth of at least 10 mm and stirred gently with a rod until the reading stabilizes — this value is not recorded. The rest of the first extract is decanted into a second beaker, the electrode is immersed without washing (at least 10 mm) and left without stirring until the reading stabilizes — this is the first measurement. The second extract is measured in the same way (electrode not washed, no stirring) — this is the second measurement.

CALCULATION, PRECISION, TEST REPORT (clauses 9–11). If the two pH values, expressed to the nearest 0,1, differ by more than 0,2, the procedure is repeated on other specimens; the mean is calculated from two valid measurements. Interlaboratory trial: 9 laboratories, 7 samples, analysis according to ISO 5725-2 — with potassium chloride solution as the extracting solution the reproducibility limit R = 1,1 pH. Test report: reference to ISO 3071:2020, mean pH to the nearest 0,1, pH of the extracting solution, its temperature, any factors that may have affected the result (including resistance of the specimen to wetting out), date of the test.

EDITION. The fourth edition ISO 3071:2020 (ISO/TC 38 "Textiles") cancelled and replaced the third edition ISO 3071:2005, which was technically revised. Changes according to the foreword: clause 7 specifies two specimens instead of three, and in 8.1 water has been omitted as an extracting solution. iTeh catalogue card of ISO 3071:2020 (read on 06.11.2026): status "Published", publication 27.01.2020, ICS 59.080.01, ISO/TC 38/WG 22, stage "9093 – International Standard confirmed" (confirmed at systematic review); next to it EN ISO 3071:2020.

STATUS (as of 06.11.2026). The card of PN-EN ISO 3071:2020-08 (English version) has no withdrawal label: title "Tekstylia -- Oznaczanie pH ekstraktów wodnych" (Textiles — Determination of pH of aqueous extracts), publication 11-08-2020, 18 pages, Consumer Products Sector, KT 26 Textile Products, "Adopts: EN ISO 3071:2020 [IDT], ISO 3071:2020 [IDT]", "Replaces: PN-EN ISO 3071:2007 - Polish version", ICS 59.080.01; the card has no "Directive" or "Mandate" fields. "Scope" field (description in Polish, our translation): "This standard describes a method for determining the pH of aqueous extracts of textiles. The method can be used for textiles in any form (e.g. fibres, yarns, fabrics)." As a related product the card lists only PN-EN ISO 3071:2007 (Polish version); a Polish version of the 2020 edition is not listed there, and on 06.11.2026 the PKN search returned a server error, so we did not review the list of all editions. We did not have the text of PN-EN ISO 3071:2007; according to the foreword of ISO 3071:2020 the previous ISO edition (2005) provided for three specimens and allowed water as the extracting solution.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database refreshed from the production server on 02.11.2026 and current PCA documents, read on 06.11.2026). Number 3071 appears in 8 records at 8 Polish laboratories: AB 062, AB 077, AB 198, AB 910, AB 1401, AB 1417, AB 1573, AB 1915 — one each. In the current PCA documents of these 8 laboratories the standard occurs 8 times in total — as many as in the copy; no entry is suspended, the AB 910 entry belongs to the flexible scope of accreditation (mark "E"). Notations: "PN-EN ISO 3071:2020-08" (7 laboratories) and "PN-EN ISO 3071" without year (AB 910). In the database copy the number also appears in 10 records at 8 Czech laboratories (notation "ČSN EN ISO 3071", partly as the basis of in-house procedures). The "Laboratories" tab ("PN-EN ISO 3071") shows 16 laboratories: these 8 Polish and 8 Czech (tab query on labcoda.pl, 06.11.2026).

WHAT THE LABORATORIES TEST (database copy and PCA documents, complete entries). pH of aqueous extracts, potentiometric method: textiles, woven fabrics, yarn, clothing, upholstery fabrics and finished products — range 4–11 (AB 062); flat textiles: woven fabrics, knitted fabrics, yarn, nonwovens, coated products, clothing, finished products — range 3–10 (AB 1573) and 4,01–9,21 (AB 1915). pH, potentiometric method: textiles, artificial leather, woven fabrics, yarn, clothing and finished products — range 3–10 (AB 077). pH of the aqueous extract, potentiometric method: textiles, woven fabrics, knitted fabrics, yarn, clothing, hosiery — range 3–10 (AB 1417); textile products, leather and leather products — range 2–14 (AB 1401). pH of the aqueous extract, electrometric method: flat textiles — range 1–12 (AB 198). Safety tests, pH value, potentiometric method: consumer products, leather, leather-like and textile products, plastic products and raw materials for their production, children's articles, toys, finger paints — in one entry with PN-EN ISO 4045, PN-EN ISO 13688, PN-EN 420, PN-EN ISO 20345, PN-EN 71-7, procedure PB-DLS/47, Directive 89/686/EEC and Regulation (EU) 2016/425 (AB 910). The text of the standard we read gives no measuring range — the ranges in the entries are ranges declared by the laboratories.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — the extracting solution: the 2020 edition provides only 0,1 mol/l potassium chloride; an extract in water alone (allowed in the 2005 edition) is a different test, and its result is not a result according to ISO 3071:2020. Second — the water for the solution: pH 5,0–7,5 checked at first use; the pH of the extracting solution goes into the test report because it affects the result. Third — the measurement sequence: the first portion of the first extract only serves to condition the electrode (it is not recorded), the electrode is not washed between extracts, and the reading is taken without stirring; washing the electrode with water or reading while stirring are different conditions. Fourth — agreement of the two specimens: a difference above 0,2 pH means repeating on new specimens, not averaging. Fifth — comparison between laboratories or with a limit value: the reproducibility limit is 1,1 pH (9 laboratories, 7 samples), so two results from different laboratories differing by less than 1,1 pH do not contradict each other. Sixth — the subject: the scope of the standard is textiles (clause 1); the entries of AB 1401 ("leather and leather products") and AB 910 (including leather products, plastic products, finger paints) also cover other materials, and AB 910 cites standards for other products alongside — the test report must state according to which document a given product was tested. We do not know these laboratories' validation; this is material to check in the specific scope, not evidence of an error.

WHAT WE DO NOT GIVE. We did not read Annex A (preparation of buffers) or the bibliography. We did not check the status of the standards cited alongside in the AB 910 entry (PN-EN ISO 4045, PN-EN ISO 13688, PN-EN 420, PN-EN ISO 20345, PN-EN 71-7); nor do we give pH limit values from product standards or legislation — we did not check references to ISO 3071 in legislation.

Method principle

A test portion of the textile, cut into small pieces, is shaken in 0,1 mol/l potassium chloride solution at room temperature, and the pH of the extract obtained is measured electrometrically with a glass electrode; the result is the mean of two concordant measurements (difference not greater than 0,2 pH) to the nearest 0,1 pH (ISO 3071:2020, clauses 4, 8, 9).

Applications

• Textiles in any form: fibres, yarns, fabrics (ISO 3071:2020, clause 1)
• Checking the acidity or alkalinity of a product against required pH limits of the extract, and an index of its processing history (introduction of the standard)
• In accreditation scopes: textiles, woven fabrics, knitted fabrics, yarn, nonwovens, coated products, clothing, hosiery, upholstery fabrics, finished products; alongside also leather, leather products and consumer products
• In accreditation scopes: 8 Polish laboratories — declared ranges from 1–12 to 2–14 pH, potentiometric or electrometric method

Key parameters

Standard

Standard number

PN-EN ISO 3071:2020-08 (English version; adopts EN ISO 3071:2020 and ISO 3071:2020 [IDT])

Title (PL)

Tekstylia — Oznaczanie pH ekstraktów wodnych

Title (EN)

Textiles — Determination of pH of aqueous extract

Step-by-step procedure

1. Specimens

   From a representative laboratory sample, pieces with sides of about 5 mm, handled as little as possible; two specimens of (2,00 ± 0,05) g (clause 7).

2. Extract

   Each specimen with 100 ml of 0,1 mol/l KCl solution in a stoppered flask; brief shaking by hand, then mechanical shaking for 2 h ± 5 min at room temperature (8.1).

   ⏱ Time: 2 h ± 5 min

3. Calibration

   Record the temperature of the extracting solution; calibrate the pH meter at the temperature of the extract and check with two buffers; immerse the electrode several times in the KCl solution until stable (8.2).

4. Measurement

   First portion of the first extract with stirring — not recorded; rest of the first extract, electrode not washed, ≥ 10 mm, without stirring — first measurement; second extract in the same way — second measurement (8.2).

5. Result

   Difference above 0,2 pH — repeat on other specimens; otherwise the mean to the nearest 0,1 pH, reported with the pH and temperature of the extracting solution (clauses 9, 11). PN-EN ISO 3071:2020-08 — current (PKN card, 06.11.2026; English version).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• TECHNICAL NOTE: the 2020 edition does not allow water as the extracting solution — a result from a water extract without KCl is not a result according to this edition
• TECHNICAL NOTE: reproducibility limit 1,1 pH — when comparing results of different laboratories or with a limit value
• Preparing water and buffers (potassium permanganate, sodium hydroxide, sulfuric acid) — rules for working with corrosive and oxidizing reagents

Frequently asked questions