📄 Grammage of paper and board — mass per unit area in g/m², gravimetric method: at least 20 test pieces of 50 000–100 000 mm², result to three significant figures; conditioned, oven-dry and “as-taken” grammage; PN-EN ISO 536

Materials and NDT PN-EN ISO 536

Overview

WHAT THE STANDARD COVERS. ISO 536:2019 (clause 1) specifies a method for determining the grammage of paper and board. Grammage is the mass of a unit area of paper or board determined by a specific method of test; it is expressed in grams per square metre (3.1). Principle (clause 4): the area and mass of the test pieces are determined and the grammage is calculated. Normative references: ISO 186 (sampling to determine average quality), ISO 187 (standard atmosphere for conditioning and testing) and ISO 287 (determination of moisture content by oven-drying). The “Scope” field of the PKN card of PN-EN ISO 536:2020-08 (English version, scope description in Polish), in full (in our translation): “This document gives a method for determining the grammage of paper and board.”

APPARATUS (clause 5). The cutting device must repeatedly and cleanly cut test pieces to within ±1,0 % of the same nominal area; this is checked frequently by measurement. If this accuracy is attained, the nominal area is used for calculation; if it cannot be attained for a given paper or board, each test piece is measured to the nearest 0,5 mm and its area calculated (5.1). The balance must weigh to within 0,5 % of the true mass over the whole range used and detect a change in mass of ±0,2 % (5.2). Special sheet-weighing balances indicating the grammage of a test piece of defined area directly may be used if they meet the same conditions and each weighed test piece has 50 000 mm² (500 cm²) to 100 000 mm² (1000 cm²); during weighing the balance is protected from draughts (5.3).

SAMPLING AND CONDITIONING (clauses 6–7). Units and sheets are selected and specimens taken according to ISO 186; when another type of sample is tested, it must be ensured that the specimens taken are representative of the sample received. If possible, at least five specimens are taken, with enough area to cut at least 20 test pieces. For “as-taken” grammage the influence of the ambient atmosphere on the moisture content of the specimens is kept to a minimum. For conditioned and oven-dry grammage the specimens are conditioned according to ISO 187.

PROCEDURE (clause 8). Conditioned grammage is determined by preparing and weighing the test pieces in the same atmosphere in which the specimens were conditioned. At least 20 test pieces are cut from at least five specimens, if possible the same number from each. Each test piece is to have from 50 000 mm² (preferably 200 mm × 250 mm) to 100 000 mm² and may consist of several smaller pieces. Where little material is available and a test piece cannot be made up of smaller pieces, a test area of not less than 10 000 mm² (100 cm²) may be used, but it must be reported as a deviation from the preferred range of 50 000–100 000 mm². If the area variation of the test pieces exceeds the limit of 5.1 at the moisture content at which grammage is determined, or is unknown, each test piece is measured to the nearest 0,5 mm. The mass (or the grammage indicated by a sheet-weighing balance) is recorded to three significant figures; it is recommended, especially with small pieces, not to touch the test pieces with bare hands.

CALCULATION AND REPORT (clauses 9–10). Grammage of each test piece: g = m/A × 10⁶, where m — mass in grams, A — area in square millimetres (measured, or nominal if 5.1 is met) — formula (1); with a sheet-weighing balance g = (A1/A) × g1, where g1 — grammage indicated by the balance, A1 — area for which the balance is calibrated — formula (2) (point 9.2 refers here to “a balance as described in 5.2”, although the sheet-weighing balance is described in 5.3 — so in the English and French text). The mean and standard deviation are given to three significant figures. The report includes, among other things: reference to ISO 536, date and place of testing, sample identification, the conditioning atmosphere (unless “as-taken” grammage was determined), the condition of the test pieces at the time of weighing (conditioned, oven-dry or “as taken”), the test piece area — outside 50 000–100 000 mm² as a deviation, the number of replicates, the mean and standard deviation, for specimens from several positions across a reel or sheet — data separately for each position, and any departure from the procedure.

ANNEX A (normative). Oven-dry grammage: if necessary (5.1), the area of each test piece is measured after conditioning, the test pieces are dried according to ISO 287 and weighed. “As-taken” grammage concerns the material in the condition at the time of sampling: it is cut and weighed as quickly as possible; near the top of a reel it is cut from such a depth that the moisture content has not been changed by the surroundings.

EDITION. The fourth edition ISO 536:2019 (ISO/TC 6/SC 2) replaced the third, ISO 536:2012, after technical revision: inconsistencies were corrected (e.g. 5.1 allows calculation on the nominal area, which the subsequent clauses previously did not recognise), clause 8 was worded more sharply for a reduced test area, the report was extended (clause 10) and “as-taken” grammage near the top of a reel was described more precisely (A.2). In the read excerpt of ISO 536:2012 (French edition), clause 6 is sampling, formula (1) is calculated from the mass and area of each test piece, and a formula from the mean mass and mean area was also permitted; clause 7 required the condition of the test pieces at the time of weighing to be stated for oven-dry, “as-taken” or other-atmosphere grammage. EN ISO 536:2020 (February 2020, approved by CEN on 30 November 2019, CEN/TC 172 together with ISO/TC 6) adopts ISO 536:2019 without modification and superseded EN ISO 536:2012; conflicting national standards were to be withdrawn by August 2020 at the latest. In the iTeh catalogue (read on 06.11.2026) ISO 536:2019 has the status “Published” and stage “9093 – International Standard confirmed” (from 18.03.2025), and ISO 536:2012 — “Withdrawn”.

STATUS (state of the PKN card on 06.11.2026). The card of PN-EN ISO 536:2020-08 (English version) has no withdrawal label: published 06-08-2020, 20 pages, price group K, Consumer Products Sector, KT 25 Pulp, Paper, Board and their Products, “Adopts: EN ISO 536:2020 [IDT], ISO 536:2019 [IDT]”, “Supersedes: PN-EN ISO 536:2012 - English version, PN-EN ISO 536:2012 - Polish version, PN-EN ISO 536:2012 - German version”, ICS 85.060. There is no Polish version of the 2020 edition in the search results — the last Polish version is PN-EN ISO 536:2012. The card of PN-EN ISO 536:2012 (Polish version) has the heading “Withdrawn and replaced by PN-EN ISO 536:2020-08 - English version”: published 21-08-2014, withdrawn 06-08-2020, 14 pages, KT 25, “Adopts: EN ISO 536:2012 [IDT], ISO 536:2012 [IDT]”, “Supersedes: PN-EN ISO 536:2011 - English version”. PKN search, query “ISO 536” (06.11.2026): alongside is also the withdrawn PN-ISO 536:1996 (Polish version, adopted ISO 536:1995), according to the list replaced by PN-EN ISO 536:2011 (English version), whose card was not among the results.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database of 02.11.2026 and current PCA documents downloaded on 06.11.2026). The number ISO 536 (with no further digits and no digits before it — excluded among others ISO 7536, ISO 8536-4 and ISO 16536) appears in 7 records at 7 Polish laboratories, one each: AB 065, AB 079, AB 184, AB 185, AB 249, AB 1510, AB 1673. Forms: “PN-EN ISO 536:2020-08” (AB 079, AB 184, AB 185, AB 1510, AB 1673), “PN-EN ISO 536:2020-08 (idt EN-ISO 536:2020) (idt ISO 536:2019)” (AB 065) and “PN-EN ISO 536:2012 z wyłączeniem p. 6” [excluding point 6] (AB 249). In the current PCA documents of six of these laboratories the standard appears in one item each — the same as in the copy; for AB 1673 the PCA page (read on 06.11.2026) had no scope document to download, so we know its item only from the database copy (issue no. 9 of 19.01.2026). Among Czech laboratories the number is held by one (1087 — “ČSN EN ISO 536”, board packaging). The “Laboratories” tab (“PN-EN ISO 536”) shows 8 laboratories: these 7 Polish and 1 Czech (tab query reproduced on the database copy on 06.11.2026).

WHAT THE LABORATORIES TEST (database copy and PCA documents, complete items). Paper, board and paper products — grammage in the range 20–2500 g/m² and mass, gravimetric method (AB 065); materials and articles of paper and board — grammage 25,0–1000 g/m², gravimetric method (AB 079); paper, board and paper products — grammage and mass (AB 1510); paper and board — grammage 90–2200 g/m², gravimetric method (AB 1673, database copy only); paper and board in a transport packaging test laboratory — grammage (AB 184); paper, board and paper products — grammage, gravimetric method (AB 185); papers and boards — grammage, gravimetric method, according to the 2012 edition without point 6 (AB 249).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — moisture condition: conditioned, oven-dry and “as-taken” grammage are three different numbers for the same sheet; a result without the condition of the test pieces at the time of weighing (clause 10 e) cannot be compared with a requirement. Second — conditioning: for conditioned grammage the test pieces are cut and weighed in the same atmosphere in which they were conditioned; weighing in another atmosphere does not meet this condition. Third — area: the nominal area may be used only if the device cuts to within ±1,0 % and this is checked frequently; otherwise each test piece is measured. Fourth — small test piece: an area below 50 000 mm² (at least 10 000 mm²) is permitted only as a deviation recorded in the report. Fifth — number of test pieces: a result from a few cuts of one sheet does not meet the requirement of at least 20 test pieces from at least five specimens (if there is enough material). Sixth — edition and sampling: AB 249 cites the PN-EN ISO 536:2012 edition, withdrawn and replaced by PN-EN ISO 536:2020-08 (withdrawal date 06-08-2020), and excluding point 6 (in the 2012 edition — sampling): the result concerns the sample delivered to the laboratory, not the whole product from which it was taken; in the 2012 edition the rules for taking the area (5.1 — mean area from verification measurements) and for calculation (9.1 — a formula from the mean mass and mean area permitted) were also worded differently. Seventh — mass: at AB 065 and AB 1510 “mass” stands next to grammage — it is an intermediate quantity (m in formula 1), not grammage.

WHAT WE DO NOT GIVE. The read excerpts of ISO 536:2019 (English edition: foreword, table of contents, clauses 1–5.1 and 9–10, Annex A; French edition: clauses 1–10 and Annex A) end before Annex B. We do not give precision data (Annex B — repeatability and reproducibility), the bibliography or the content of ISO 186, ISO 187 and ISO 287 (e.g. the conditions of the standard atmosphere and of drying); we did not check the status of these three standards (ISO 536:2019 cites them undated). We did not check citations of the standard in regulations.

Method principle

Test pieces of known area are cut (with a device accurate to ±1,0 % of the nominal area or with each test piece measured to the nearest 0,5 mm), weighed on a balance accurate to 0,5 % of the mass, and the grammage of each test piece g = m/A × 10⁶ in g/m² is calculated (m in grams, A in mm²), followed by the mean and standard deviation to three significant figures; the condition of the test pieces at the time of weighing — conditioned according to ISO 187, oven-dry according to ISO 287 or “as taken” — is part of the result (ISO 536:2019, clauses 4–10, Annex A).

Applications

• Paper and board — grammage (mass per unit area) in g/m² (ISO 536:2019, clause 1)
• Conditioned, oven-dry and “as-taken” grammage (clauses 7–8, Annex A)
• In accreditation scopes: paper, board, paper products, materials and articles of paper and board, paper and board in transport packaging testing
• In accreditation scopes: 7 Polish laboratories — grammage ranges 20–2500 g/m², 25,0–1000 g/m² and 90–2200 g/m², gravimetric method

Key parameters

Standard

Standard number

PN-EN ISO 536:2020-08 (English version; adopts EN ISO 536:2020 and ISO 536:2019 [IDT])

Title (PL)

Papier i tektura — Oznaczanie gramatury

Title (EN)

Paper and board — Determination of grammage

Step-by-step procedure

1. Sampling

   Specimens according to ISO 186; if possible, at least 5 specimens and area for at least 20 test pieces; for “as-taken” grammage — limit the influence of the surroundings on moisture (clause 6).

2. Conditioning

   For conditioned and oven-dry grammage — according to ISO 187 (clause 7).

3. Cutting and weighing

   At least 20 test pieces of 50 000–100 000 mm², weighed in the conditioning atmosphere; mass to three significant figures; without touching with bare hands (clause 8). Oven-dry grammage: drying according to ISO 287 (Annex A.1).

4. Calculation and result

   g = m/A × 10⁶ for each test piece, mean and standard deviation to three significant figures; in the report the condition of the test pieces, the area and deviations (clauses 9–10). PN-EN ISO 536:2020-08 — current (state of the PKN card on 06.11.2026; English version).

Required equipment and apparatus

Health and safety (OHS)

• SUBSTANTIVE NOTE: grammage without the condition of the test pieces (conditioned, oven-dry, “as taken”) is not comparable
• SUBSTANTIVE NOTE: a test piece smaller than 50 000 mm² — only as a deviation recorded in the report, at least 10 000 mm²
• Work with the cutting device — blades

Frequently asked questions