🔩 Determination of the density of non-cellular plastics (void-free mouldings and extrusions, powders, flakes and granules) by three methods: A — immersion (weighing in air and in liquid, sinker for plastics lighter than the liquid), B — liquid pycnometer (powders, granules, small pieces, 1–5 g), C — titration (any void-free form); conditions according to the 2019 edition: liquid at 23 °C ± 2 °C (or 27 °C), balance ± 0,1 mg, at least three specimens, mean to three decimal places (the 2025 edition adds temperature requirements for the liquid and air and revises the requirements for the pycnometer, thermometer and liquids); 2025 edition with buoyancy-of-air correction within the formulae themselves, PN-EN ISO 1183-1

Materials and NDT PN-EN ISO 1183-1

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 1183-1:2026-01 (English version; scope in Polish on the card), in full (our translation): “This document specifies three methods for determining the density of non-cellular plastics in the form of void-free moulded parts produced by various techniques, as well as powders, flakes and granules. - Method A: immersion method, applicable to determining the density of solid plastics (except powders) without voids. - Method B: liquid pycnometer method, applicable to particles, powders, flakes, granules or small pieces of finished parts. - Method C: titration method, applicable to plastics in any void-free form. NOTE Density is frequently used to follow variations in physical structure or composition of plastics. Density can also be useful in assessing the uniformity of samples or test specimens. The density of plastics often depends on the choice of method of preparing the test specimen. In such a case all details of the specimen preparation method should be included in the relevant material specification. This note applies to all three methods. Annex C contains further information on calculating the volume of the test specimen used for density determination when method A (immersion method) is used.” We read TWO documents: the preview of ISO 1183-1:2025 (cover, table of contents and foreword with the list of changes — the text of the clauses is not in it) and the preview of the previous edition ISO 1183-1:2019 from the cover to 5.2.4.5 (page 5). The procedure details given below come from the 2019 EDITION — in the 2025 edition, among other things, the formulae and the requirements for pycnometer, thermometer and liquids were changed, so figures from 2019 must be checked in the 2025 text.

ACCORDING TO THE FOREWORD OF ISO 1183-1:2025 (fourth edition, 2025-06). The standard was prepared by ISO/TC 61/SC 5 together with CEN/TC 249 (Vienna Agreement); it replaces the third edition (2019) after technical revision. Changes: in Clause 4 temperature requirements for the immersion liquid and air were added; in 5.1 a variant of the immersion method without a wire to suspend the specimen was introduced; the requirements for pycnometer, thermometer and immersion liquids were changed; the classic procedure with a wire was clarified; the density formulae in 5.1.4 now include buoyancy in air; Clause 6 (buoyancy correction) was deleted — the correction was moved to 5.1.4.4 and the calculation of air density to Annex B, which became normative and now covers only air density (correction in the new formulae 3 and 4); Annex C (formulae for the volume of specimens in the immersion method) and Annex D (explanation of the formulae) were added. Table of contents 2025: scope, references, terms and symbols, conditioning and test atmosphere, methods A (apparatus, liquid, specimens, procedure), B and C, precision (Clause 6), test report, Annexes A (liquids for method C), B (normative — air density), C, D, E (precision statement).

ACCORDING TO THE TEXT OF ISO 1183-1:2019 (Clauses 1–5.2.4.5 — REPLACED edition). Foreword 2019: ISO/TC 61/SC 5, the third edition replaced ISO 1183-1:2012 (buoyancy correction revised); the corrected version corrected a definition in Formula (2). General warning. Scope — as on the card (without the sentence on Annex C). References: ISO 291, ISO 472. Definitions: mass; apparent mass (from weighing with a calibrated balance); density ρ = m/V at temperature T; specific volume v = V/m = 1/ρ. Conditioning (4): atmosphere according to ISO 291; generally not required, because the determination itself brings the specimen to the test temperature; specimens whose density changes during the test by more than the required accuracy are conditioned according to the material specification. Method A (5.1): analytical balance or density instrument ± 0,1 mg (also automatic); vessel, stationary support over the pan, thermometer graduated in 0,1 °C (0–30 °C), corrosion-resistant wire of diameter not greater than 0,5 mm, sinker (when the specimen density is lower than that of the liquid), pycnometer with side-arm overflow capillary and liquid bath ± 0,5 °C (for the density of liquids other than water); liquid — freshly distilled or deionized water or another liquid with not more than 0,1 % of wetting agent, not affecting the specimen (the density of liquids from an accredited source with a certificate need not be measured); specimens void-free, not powder, preferably at least 1 g, with a smooth surface without cavities (air bubbles introduce errors); weighing in air on the wire, then in liquid at 23 °C ± 2 °C (or 27 °C ± 2 °C), after removing bubbles with a fine wire; density of a liquid other than water — by pycnometer at 23 °C ± 0,5 °C: ρIL = mIL/mW × ρW (Formula 1); density of the specimen ρS = mS,A × ρIL / (mS,A − mS,IL) (Formula 2); with sinker ρS = mS,A × ρIL / (mS,A + mK,IL − mS+K,IL) (Formula 3); buoyancy of the wire in air is normally neglected; at least three specimens, mean to three decimal places. Method B (5.2): balance ± 0,1 mg, pycnometer, bath, desiccator with vacuum; specimens (powders, granules, flakes) as received, 1–5 g; pycnometer empty, with material, covered with liquid and deaerated under vacuum, filled at 23 °C ± 0,5 °C; then with deaerated water; ρS = mS × ρIL / (m₁ − m₂) (Formula 4, m₁ — mass of liquid in the empty pycnometer, m₂ — in the pycnometer with specimen); at least three specimens.

STATUS (PKN catalogue cards as of 02.10.2026). The card of PN-EN ISO 1183-1:2026-01 (English version, published 07-01-2026, 34 pages, price group Q) has no “Withdrawn” header: Chemistry Sector, KT 141 Plastics, ICS 83.080.01, “Introduces: EN ISO 1183-1:2025 [IDT], ISO 1183-1:2025 [IDT]”, “Replaces: PN-EN ISO 1183-1:2019-05 – English version”. The card of PN-EN ISO 1183-1:2019-05 has the “Withdrawn” header: withdrawal date 07-01-2026, “Replaced by: PN-EN ISO 1183-1:2026-01”. The three questions for a withdrawn edition: when — 07.01.2026; replaced by what — PN-EN ISO 1183-1:2026-01 (card without the “Withdrawn” header, end of the chain); what changed for the result — according to the foreword of ISO 1183-1:2025 the correction for buoyancy of air entered the density formulae themselves (previously it was a separate Clause 6 and informative Annex B), a wire-free immersion variant was added and the requirements for pycnometer, thermometer, liquids and the temperature of liquid and air changed. The EVS catalogue (read 02.10.2026) lists ISO 1183-1:2025 as valid from 19.06.2025, and ISO 1183-1:2019 as the previous one.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 02.10.2026). The number 1183-1 appears in 8 records at 8 laboratories: AB 001, AB 005, AB 023, AB 041, AB 128, AB 163, AB 237, AB 1256. In the current scopes on the PCA website (read 02.10.2026, issues from 16.07.2025 to 20.07.2026): the 2026-01 edition is given by AB 163 and AB 237, “EN ISO 1183-1:2025” without the PN prefix — by AB 1256, the 2019-05 edition — by AB 001 and AB 005, the number without a year — by AB 023, AB 041 and AB 128. The “Laboratories” tab searches for entries STARTING WITH “PN-EN ISO 1183-1” and shows 7 laboratories; AB 1256 has the entry “EN ISO 1183-1:2025” in the database, so it does not appear in this tab — checked with the tab query on the production server labcoda.pl on 02.10.2026.

WHAT THE LABORATORIES TEST (PCA entries). Non-cellular plastics and products made of them — “Density”: by method A / immersion (AB 001, AB 023, AB 041, AB 128, AB 163, AB 237, AB 1256), “by a gravimetric method” from 0,5 to 3 g/cm³ (AB 005); ranges: from 0,1 to 1 g/cm³ (AB 041 — pipes, fittings and products, flexible scope), from 0,3 to 2 g/cm³ (AB 237, AB 1256), lower limit of quantification 0,3 g/cm³ (AB 163), from 0,9 to 2 g/cm³ (AB 128). No laboratory explicitly indicates methods B or C.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Edition: laboratories with the 2019-05 edition calculate density with formulae in which buoyancy of air was a separate correction; the 2026-01 edition builds it into the formulae — when comparing results from the two editions one has to know whether the correction was applied. Liquid and temperature (according to the 2019 edition; in the 2025 edition temperature requirements for the liquid and air were added in Clause 4 and the requirements for the thermometer and liquids in 5.1 were revised — we do not have the text): liquid at 23 °C ± 2 °C (or 27 °C), wetting agent not more than 0,1 %; air bubbles on the specimen introduce errors (5.1.3) — the standard requires them to be removed with a fine wire and requires a smooth surface without cavities. Plastics lighter than the liquid: a density below that of the liquid requires a sinker and Formula 3 instead of 2 — this concerns ranges from 0,1 g/cm³ (AB 041) and from 0,3 g/cm³ (AB 163, AB 237, AB 1256). Preparation: density often depends on how the specimen is prepared — details are to be in the material specification. Number of specimens (according to the 2019 edition): at least three, mean to three decimal places.

WHAT WE DO NOT STATE. Of the 2025 edition we do not have the text of any clause — we therefore give neither the new Formulae 3 and 4, nor the air temperature requirements, nor the wire-free variant, nor precision data (Clause 6 and Annex E); of the 2019 edition we do not have method C (titration), Clause 6 (buoyancy correction), the test report or the annexes.

Method principle

The density of a void-free plastic is determined from the mass of the specimen and its volume: by the immersion method — from the difference between mass in air and in a liquid of known density (sinker for lighter plastics), by the pycnometer method — from the mass of liquid displaced by powder or granules (the titration method C is not in the parts we read); the 2025 edition includes buoyancy of air in the formulae.

Applications

• Non-cellular plastics, mouldings, extrusions, pipes and fittings — 8 laboratories in PCA scopes
• Powders, granules and flakes of plastics (liquid pycnometer method)
• Following changes in structure and composition and the uniformity of plastics

Key parameters

Standard

Standard number

PN-EN ISO 1183-1:2026-01 (wersja angielska; EN ISO 1183-1:2025 IDT, ISO 1183-1:2025 IDT)

Title (PL)

Tworzywa sztuczne — Metody oznaczania gęstości tworzyw sztucznych nieporowatych — Część 1: Metoda zanurzeniowa, metoda piknometru cieczowego i metoda miareczkowa

Title (EN)

Plastics — Methods for determining the density of non-cellular plastics — Part 1: Immersion method, liquid pycnometer method and titration method

Step-by-step procedure

1. Choice of method and specimen

   A — solid void-free specimens (preferably ≥ 1 g, smooth); B — powders and granules 1–5 g; C — any form. PN-EN ISO 1183-1:2026-01 current, 2019-05 edition withdrawn 07.01.2026 (PKN cards as of 02.10.2026).

2. Conditioning

   Atmosphere according to ISO 291; generally not required, exceptions according to the material specification; in the 2025 edition temperature requirements for liquid and air were added.

3. Method A

   Mass in air, then in liquid (23 °C ± 2 °C according to the 2019 edition; the temperature requirements were changed in the 2025 edition) after removing bubbles; plastics lighter than the liquid — with a sinker.

4. Method B

   Pycnometer empty, with material, with liquid after deaeration under vacuum, at 23 °C ± 0,5 °C (2019 edition; the 2025 edition revises the requirements for the pycnometer, thermometer and liquids); then with deaerated water.

5. Result

   Density according to the formulae of the 2025 edition (with buoyancy of air — we do not have the text); according to the 2019 edition at least three specimens, mean to three decimal places.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The standard gives a general warning about possible hazardous materials and operations; liquids other than water (especially in method C) — according to the safety data sheets
• TECHNICAL NOTE: the 2019-05 edition was withdrawn on 07.01.2026 — in the 2026-01 edition the buoyancy-of-air correction is in the formulae; plastics lighter than the liquid require a sinker

Frequently asked questions