🔩 Density of paints, varnishes and similar products of low or medium viscosity by the pyknometer method — metal pyknometer (50 or 100 cm³) or glass Gay-Lussac pyknometer (10–100 cm³), reference temperature 23,0 °C ± 0,5 °C, de-aeration of the sample before determination (since 2023), ρ = (m2 − m1)/Vt without air buoyancy correction, precision r = 0,005 and R = 0,007 g/cm³ for coating materials, PN-EN ISO 2811-1

Materials and NDT PN-EN ISO 2811-1

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 2811-1:2023-03, in full (our translation of the Polish card text): “This document specifies a method for determining the density of paints, varnishes and related products using a metal pyknometer or a Gay-Lussac pyknometer. The method is limited to materials of low or medium viscosity at the test temperature. For high-viscosity materials the Hubbard pyknometer can be used (see ISO 3507).” We read the text of the standard in the preview of ISO 2811-1:2023 from the cover to clause A.2 of Annex A (formulae for the pyknometer volume and explanation of symbols); we do not have Table A.1 (density of water), the end of Annex A or Annex B (temperature changes, formula B.2).

ACCORDING TO THE TEXT OF ISO 2811-1:2023 (foreword, Clauses 1–11, Annex A up to A.2). The standard was prepared by ISO/TC 35/SC 9 with CEN/TC 139. The fourth edition replaces the third (2016); changes: in 8.2 a requirement to de-aerate the sample before the determination was added to obtain repeatable results, the text was editorially revised and the references updated. Scope (Clause 1): a method for paints, varnishes and similar products with a metal or Gay-Lussac pyknometer, limited to materials of low or medium viscosity at the test temperature; for high-viscosity materials — the Hubbard pyknometer (ISO 3507). Normative references: ISO 1513 (examination and preparation of samples), ISO 3696 (water), ISO 15528 (sampling). Definition (3.1): density ρ — mass divided by the volume of a portion of material, in g/cm³. Principle (Clause 4): the pyknometer is filled with the product; the density is calculated from the mass of the product and the known volume of the pyknometer. Temperature (Clause 5): the effect of temperature on density is very significant; the reference temperature is (23,0 ± 0,5) °C, for comparison another agreed temperature can be used, e.g. (20,0 ± 0,5) °C according to metrological regulations (B.2); sample and pyknometer are conditioned to this temperature, and during the test the temperature must not change by more than 0,5 °C. Apparatus (Clause 6): metal pyknometer 50 or 100 cm³, cylindrical, of corrosion-resistant material, with a close-fitting lid with a central hole and concave underside (Figure 1), or glass Gay-Lussac pyknometer 10–100 cm³ (Figure 2); analytical balance with a maximum permissible error of 1 mg for pyknometers below 50 ml and 10 mg for 50–100 ml; thermometer with a maximum permissible error of 0,2 °C (usually resolution 0,05 °C); thermostatic chamber accommodating balance, pyknometer and sample, or a water bath. Sampling (Clause 7): representative sample according to ISO 15528, prepared according to ISO 1513, free of air bubbles. Procedure (Clause 8): a single determination on a fresh sample; the pyknometer must be calibrated (example in Annex A); pyknometer and sample are placed in the chamber with the balance or in the bath and left for about 30 min to equalize temperature; the sample temperature tT is measured and monitored throughout the determination; the mass of the empty pyknometer m1 is recorded to 10 mg (50–100 cm³) or 1 mg (below 50 cm³); depending on the matrix, the sample is de-aerated (note: for waterborne products stirring for about 30 s at 2000 min⁻¹ has proved suitable); the pyknometer is filled without bubbles, the lid or stopper is fitted, the excess is wiped off with material moistened with solvent and with cotton wool, and it is weighed (m2); liquid on ground joints or lid contacts gives a high reading. Calculation (Clause 9): ρ = (m2 − m1)/Vt, Vt — volume of the pyknometer at the test temperature according to Annex B; without air buoyancy correction, because most filling-machine control procedures require the uncorrected value, and the correction (0,0012 g/cm³) is negligible compared with the precision; at a temperature other than the reference — formula B.2. Precision (Clause 10, 95 % probability): repeatability r = 0,001 g/cm³ for solvents and 0,005 g/cm³ for coating materials; reproducibility R = 0,002 and 0,007 g/cm³. Test report (Clause 11): among others identification of the product, reference to ISO 2811-1:2023, type of pyknometer, test temperature, result in g/cm³ rounded to 0,001 (pyknometers below 50 cm³) or 0,01 g/cm³ (50–100 cm³), deviations, unusual features, date. Annex A (informative, calibration example): the pyknometer is cleaned with a residue-free solvent, dried, left for 30 min by the balance and weighed (m1); filled with distilled or deionized grade 2 water according to ISO 3696, previously boiled and brought to a temperature not lower than 1 °C below the test temperature; brought to the test temperature, the overflow removed, dried and weighed immediately (m3) — tongs or cellulose wadding are recommended, because touching warms the pyknometer; calibration at the same temperature as the determination, otherwise a correction according to Annex B; volume Vt from formula A.1 (with densities of water, air and weights) or A.2: Vt = (m3 − m1)/(ρW − 0,0012) × 0,99985; this is where the part we read ends.

STATUS (cards as of 02.10.2026). The cards of PN-EN ISO 2811-1:2023-03 in the English version (published 20-03-2023, 22 pages, price group L) and the Polish version (published 18-07-2025, 18 pages, price group J) do not carry the heading “Wycofana” (withdrawn): Chemistry Sector, KT 175 Paints and Varnishes, ICS 87.040, “Introduces: EN ISO 2811-1:2023 [IDT], ISO 2811-1:2023 [IDT]”, “Replaces: PN-EN ISO 2811-1:2016-04 – English and Polish versions”. PN-EN ISO 2811-1:2016-04 (Polish version of 07-12-2018, introduced ISO 2811-1:2016) — withdrawn 20-03-2023; it had itself replaced PN-EN ISO 2811-1:2012. The PKN search for “PN-EN ISO 2811-1” (02.10.2026) also shows PN-EN ISO 2811-1:2002, 2011 and 2012.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read on 02.10.2026). The number 2811-1 appears in 6 records at 6 laboratories: AB 054, AB 163, AB 424, AB 556, AB 910, AB 1700. In the current scopes on the PCA website (read on 02.10.2026, issues from 03.10.2023 to 17.07.2026) the number appears at all 6: with the year “2023-03” at AB 163 and AB 1700, with the withdrawn edition “2016-04” at AB 556 (scope of 03.10.2023), without a year at AB 054, AB 424 and AB 910. No row is set in bold italics (at AB 054 and AB 1700 the suspension concerns another part of the scope). The “Laboratories” tab searches for entries STARTING WITH “PN-EN ISO 2811-1” and shows all 6 laboratories and 6 items — checked with the tab query on the labcoda.pl production server on 02.10.2026.

WHAT THE LABORATORIES TEST (items in the PCA scopes). Paints and varnishes, raw materials for paints (AB 163, AB 1700 — alongside PN-EN ISO 1513:2010), primers and facade paints for thermal insulation systems with a range of (1,0–2,5) g/cm³ alongside ETAG 004 and European Assessment Documents (AB 054), paints and primers alongside ETAG 004:2013 and EAD 040083-00-0404 (AB 556), road marking materials (AB 424), paints and varnishes alongside the procedure PB-DLS/70 (AB 910); pyknometer method.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Temperature: density depends strongly on temperature — a result without the test temperature (23,0 °C or agreed) is not comparable, and a change of more than 0,5 °C during the test invalidates the determination. Air: since 2023 the sample is de-aerated — bubbles lower the density. Viscosity: high-viscosity products require the Hubbard pyknometer (ISO 3507), not this standard. Calibration: the pyknometer volume is determined at the determination temperature or converted according to Annex B; touching with a bare hand warms the pyknometer. Rounding: a 50–100 cm³ pyknometer gives the result to 0,01 g/cm³, a smaller one — to 0,001 g/cm³. Reference: a scope with the 2016-04 edition (AB 556) does not include the de-aeration requirement.

WHAT WE DO NOT GIVE. We do not have Table A.1 (density of water as a function of temperature), the end of Annex A or Annex B — so we do not give water density values or the formula for converting density and volume to another temperature.

Method principle

A calibrated pyknometer of known volume Vt is filled with the de-aerated product at 23,0 °C ± 0,5 °C (or an agreed temperature), weighed empty (m1) and filled (m2), and the density ρ = (m2 − m1)/Vt is calculated in g/cm³, without air buoyancy correction.

Applications

• Paints, varnishes, primers and raw materials for paints — quality and filling control (6 laboratories)
• Facade paints and primers for thermal insulation systems (ETAG 004, European Assessment Documents)
• Road marking materials

Key parameters

Standard

Standard number

PN-EN ISO 2811-1:2023-03 (wersje angielska i polska; EN ISO 2811-1:2023 IDT, ISO 2811-1:2023 IDT)

Title (PL)

Farby i lakiery — Oznaczanie gęstości — Część 1: Metoda piknometryczna

Title (EN)

Paints and varnishes — Determination of density — Part 1: Pycnometer method

Step-by-step procedure

1. Sample and calibration

   Sampling according to ISO 15528, preparation according to ISO 1513 (free of bubbles); pyknometer calibrated with grade 2 water at the test temperature (Annex A). PN-EN ISO 2811-1:2023-03 current (cards as of 02.10.2026).

2. Temperature equalization

   Pyknometer and sample in the chamber with the balance or in the bath for about 30 min; measurement of the sample temperature tT and monitoring throughout the determination (change ≤ 0,5 °C).

3. Weighing the empty pyknometer and de-aeration

   m1 to 10 mg (50–100 cm³) or 1 mg (< 50 cm³); de-aeration of the sample depending on the matrix.

4. Filling and weighing

   Filling without bubbles, fitting the lid or stopper, wiping off the excess with material moistened with solvent and with cotton wool, weighing (m2).

5. Calculation and report

   ρ = (m2 − m1)/Vt, without buoyancy correction; a single determination on a fresh sample; in the report the pyknometer type, temperature and result rounded according to Clause 11.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Solvent-borne paints and cleaning solvents — flammable and harmful, work with ventilation, gloves; the part of the standard we read contains no safety warnings
• SUBSTANTIVE NOTE: a result without the test temperature is not comparable; since 2023 the sample is de-aerated, and high-viscosity products are tested with the Hubbard pyknometer (ISO 3507)

Frequently asked questions