🔩 Accelerated ageing of coatings under fluorescent UV lamps, heat and moisture — type 1A (UVA-340, peak 343 nm) to simulate UV daylight (method A), type 1B (UVA-351, peak 353 nm) for daylight through window glass (method B), type 2 (UVB-313) only by agreement, spectral distribution requirements (Tables 1 and 2), wetting by condensation or spray, radiant exposure H = ∫E dt, PN-EN ISO 16474-3

Materials and NDT PN-EN ISO 16474-3

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 16474-3:2021-06 (English version), in full (our translation of the Polish card text): “This document specifies methods for exposing coatings to fluorescent UV lamps, heat and water in apparatus designed to reproduce the weathering effects that occur when materials are exposed in actual end-use environments to daylight or to daylight filtered through window glass. The coatings are exposed to different types of fluorescent UV lamp under controlled environmental conditions (temperature, humidity and/or water). Different types of fluorescent UV lamp can be used to meet all the requirements for testing different materials. Specimen preparation and evaluation of the results are covered in other ISO documents for specific materials. General guidance is given in ISO 16474-1. NOTE Fluorescent UV lamp exposures for plastics are described in ISO 4892-3.” We read the text of the standard in the preview of ISO 16474-3:2021 from the cover to Table 2 (page 5); we do not have the rest — Table 3, clauses 5.2 onwards (test chamber, radiometer, temperature sensors, wetting), Clauses 6–9 (test specimens, test conditions with Table 4 and sets of cycles, procedure, test report) and Annex A.

ACCORDING TO THE TEXT OF ISO 16474-3:2021 (foreword, introduction, Clauses 1–5.1.4, Tables 1–2). The standard was prepared by ISO/TC 35 with CEN/TC 139. The second edition replaces the first (2013); changes: in 7.2 the difference between the temperature of the black-panel sensor and the black-standard sensor was corrected, in Table 4 the black-panel temperature is not controlled during water spray, the text was editorially revised and the references updated. Introduction: coatings are exposed to laboratory light sources to reproduce the ageing processes occurring in natural weathering or behind window glass. Normative references: ISO 1514 (panels), ISO 2808 (film thickness), ISO 4618 (terms), ISO 9370 (instrumental determination of radiant exposure), ISO 16474-1:2013 (general guidance). Definition (3.1): radiant exposure H = ∫E dt in J/m² (E — irradiance in W/m², t — time in s); with constant E — the product E·t. Principle (Clause 4): fluorescent UV lamps, when properly maintained, simulate the spectral irradiance of daylight in the UV region; exposure conditions are varied by choice of lamp type, irradiance level, temperature during UV exposure, relative humidity in light and dark periods (if required — note: commercial apparatus usually does not control humidity), type of wetting, wetting temperature and cycle, and the UV/dark cycle; wetting is usually by condensation of water vapour on the specimen surface or by spraying with demineralized or deionized water; it may include measurement of irradiance and radiant exposure in the plane of the specimens; simultaneous exposure of a similar material of known performance (control) is recommended; results from different apparatus or lamp types are not compared without an established statistical relationship for the material concerned. Light source (5.1): fluorescent UV lamps — at least 80 % of emission below 400 nm; type 1A (UVA-340) — below 300 nm less than 1 % of the total output, peak at 343 nm, to simulate daylight at 300–340 nm; type 1B (UVA-351) — below 310 nm less than 1 %, peak at 353 nm, for UV daylight behind window glass; type 2 (UVB-313) — below 300 nm more than 10 %, peak at 313 nm, only by agreement between the parties recorded in the report (note: it can emit down to 254 nm and cause ageing processes that do not occur in service); the daylight reference is CIE 85:1989, Table 4; unless otherwise agreed, method A — type 1A, method B — type 1B; lamps age significantly — without automatic irradiance control the apparatus manufacturer’s instructions must be followed; irradiance uniformity according to ISO 16474-1, at irradiance below 90 % of the maximum — periodic repositioning of specimens. Table 1 (type 1A, method A; share of irradiance in 290–400 nm, minimum / CIE 85 / maximum): λ < 290 nm — maximum 0,1 %; 290–320 nm — 5,9 / 5,4 / 9,3 %; 320–360 nm — 60,9 / 38,2 / 65,5 %; 360–400 nm — 26,5 / 56,4 / 32,8 %; compliance is checked by measuring the spectrum 250–400 nm (usually every 2 nm); limits from more than 60 measurements of lamps of different lots and ages, at least 3 sigma from the mean; the range for lamp sets from measurements at about 50 points of the exposure area. Table 2 (type 1B, method B): λ < 300 nm — maximum 0,2 %; 300–320 nm — 1,1 / ≤ 1 / 3,3 %; 320–360 nm — 60,5 / 33,1 / 66,8 %; 360–400 nm — 30,0 / 66,0 / 38,0 %; limits from 21 measurements; target values are CIE 85 multiplied by the transmittance of 3 mm window glass; this is where the part we read ends.

STATUS (cards as of 02.10.2026). The card of PN-EN ISO 16474-3:2021-06 (English version) does not carry the heading “Wycofana” (withdrawn) — the standard is CURRENT: published 29-06-2021, 30 pages, price group P, Chemistry Sector, KT 175 Paints and Varnishes, ICS 87.040, “Introduces: EN ISO 16474-3:2021 [IDT], ISO 16474-3:2021 [IDT]”, “Replaces: PN-EN ISO 16474-3:2014-02 – English version, PN-EN ISO 16474-3:2014-02 – Polish version, PN-EN ISO 16474-3:2014-02/Ap1:2016-10 – English version”. PN-EN ISO 16474-3:2014-02 (Polish version, published 18-11-2016, introduced ISO 16474-3:2013; it had itself replaced PN-EN ISO 11507:2008) — withdrawn 29-06-2021. The PKN search for “PN-EN ISO 16474-3” (02.10.2026) shows the cards 2014-02 (English and Polish) and 2021-06. There is no Polish version of the 2021 edition.

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 16474-3 appears in 6 records at 6 laboratories: AB 023, AB 128, AB 163, AB 240, AB 1424, AB 1552. In the current scopes on the PCA website (read on 02.10.2026, issues from 16.07.2025 to 01.09.2026) the number appears at all 6: with the year “2021-06” at AB 163, AB 240 and AB 1424, with the withdrawn edition “2014-02” at AB 1552, without a year at AB 023 and AB 128. No row is set in bold italics. The “Laboratories” tab searches for entries STARTING WITH “PN-EN ISO 16474-3” 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). Coatings — resistance to weathering and artificial radiation (AB 023); plastics, textiles, rubber, machine parts — resistance to solar radiation with laboratory light sources, alongside PN-EN ISO 4892-3, 16474-1 and 16474-2 (AB 128); coatings — resistance to UV radiation alongside PN-EN ISO 16474-2 and 4892-1 (AB 163); “resistance to artificial weathering, method C, cycle 4” alongside PN-EN ISO 16474-1:2014-02 (AB 240); paint systems — exposure to laboratory light sources, fluorescent UV lamps (AB 1424); resistance to UV light under controlled conditions alongside PN-EN ISO 4892-3, PV 3930 and SAE J2527 (AB 1552).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Lamp: type 1A (UVA-340) corresponds to daylight, type 1B (UVA-351) — to daylight behind glass, and type 2 (UVB-313) emits radiation shorter than in nature and may cause ageing that does not occur in service — it is permitted only by agreement recorded in the report. Spectrum: a lamp meeting Table 1 or 2 must be demonstrated by measuring the spectrum 250–400 nm; lamps age, and without irradiance control the dose changes. Comparisons: results from different apparatus and lamp types are not compared without an established statistical relationship; a control material is recommended. Material: plastics are exposed according to ISO 4892-3, not this standard. Reference: “method C, cycle 4” (AB 240) refers to Table 4, which we have not read; a scope with the 2014-02 edition (AB 1552) does not include the correction concerning black-panel temperature during spray.

WHAT WE DO NOT GIVE. We do not have Table 3 (type 2), Table 4 and the sets of exposure cycles (irradiance, temperatures, condensation and spray times), the requirements for the chamber, radiometer and sensors, specimen preparation or the test report — so we do not give any exposure cycle or test duration.

Method principle

Coatings are exposed in a chamber with fluorescent UV lamps whose spectrum complies with Table 1 (type 1A, daylight, method A) or Table 2 (type 1B, behind glass, method B), at controlled temperature, with UV/dark cycles and wetting by condensation or spray; the dose is described by the radiant exposure H = ∫E dt, and the effects are evaluated according to product standards, preferably against a control material.

Applications

• Coatings and paint systems — accelerated ageing in UV daylight or behind glass (6 laboratories)
• Assessment of UV resistance alongside standards for plastics (ISO 4892-3) and automotive standards (PV 3930, SAE J2527)
• Comparisons of coatings against a control material of known performance

Key parameters

Standard

Standard number

PN-EN ISO 16474-3:2021-06 (wersja angielska; EN ISO 16474-3:2021 IDT, ISO 16474-3:2021 IDT)

Title (PL)

Farby i lakiery — Metody ekspozycji na laboratoryjne źródła światła — Część 3: Lampy fluorescencyjne UV

Title (EN)

Paints and varnishes — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps

Step-by-step procedure

1. Choice of method and lamps

   Method A — type 1A lamps (UVA-340), method B — type 1B (UVA-351), type 2 only by agreement; check of the spectrum against Table 1 or 2. PN-EN ISO 16474-3:2021-06 current (cards as of 02.10.2026).

2. Specimens

   According to the product standard, on ISO 1514 panels, with thickness measured according to ISO 2808; control material recommended — details (Clause 6) NOT GIVEN.

3. Exposure conditions

   Irradiance, temperature, humidity, type and cycle of wetting (condensation or spray) and the UV/dark cycle according to Table 4 — values NOT GIVEN.

4. Exposure

   Monitoring of irradiance (lamps age), repositioning of specimens at irradiance < 90 % of maximum, measurement of radiant exposure H = ∫E dt.

5. Evaluation and report

   Evaluation of changes in properties according to product standards; in the report the lamp type and any agreement on type 2 — other requirements (Clause 9) NOT GIVEN.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• UV radiation from the lamps — do not look into the source, chamber door interlocks; type 2 lamps (UVB-313) emit down to 254 nm; the part of the standard we read contains no safety warnings
• SUBSTANTIVE NOTE: the lamp type determines the spectrum — a result without the lamp type and method (A or B) is not comparable; plastics are tested according to ISO 4892-3

Frequently asked questions