🔩 Local thickness of metallic coatings, oxide layers and enamels — measurement on a cross-section under an optical microscope, at least 5 points, uncertainty up to 1 µm or 10 %; PN-EN ISO 1463

Materials and NDT PN-EN ISO 1463

Overview

WHAT THE STANDARD COVERS. ISO 1463:2021 (clause 1) specifies a method for measuring the local thickness of metallic coatings, oxide layers and porcelain or vitreous enamel coatings by microscopical examination of cross-sections with an optical microscope. The local thickness is the mean of a specified number of thickness measurements made within a reference area (definition 3.1 from ISO 2064:1996). The standard has no normative references. The "Scope" field of the PKN card of PN-EN ISO 1463:2021-10 (English version, scope description in Polish): "This document specifies a method for measuring the local thickness of metallic coatings, oxide layers, porcelain or vitreous coatings by microscopical examination of cross-sections using an optical microscope" (our translation).

PRINCIPLE AND PREPARATION OF THE CROSS-SECTION (clauses 4 and 6). A piece of the test specimen is cut out and mounted; the cross-section is prepared by grinding, polishing and etching, and the thickness of the coating cross-section is measured with a calibrated scale (note: the techniques are known to experienced metallographers, guidance for the less experienced is given in clause 5 and Annex A). The cross-section shall be perpendicular to the coating, flat, with the whole width of the coating image simultaneously in focus at the measuring magnification, without material deformed by cutting, and the coating boundaries shall be sharply defined — by contrast alone or by a narrow, clearly visible line. Annex A: to avoid rounding the edge of the coating, its free surface is supported without a gap — by applying an additional coating (overplating) or by mounting without gaps; the overplated coating usually has a similar hardness and a thickness of at least 10 µm. Annex C gives typical etchants for use at room temperature.

FACTORS OF UNCERTAINTY (clause 5). Roughness of the coating or substrate may prevent accurate measurement. A cross-section inclined to the perpendicular gives a thickness greater than the true one — an inclination of 10° contributes 1.5 % uncertainty (the same is contributed by a measuring line deviating by 10° from the perpendicular to the coating boundaries). Deformation of the coating is caused by excessive temperature or pressure when mounting soft and low-melting coatings and by excessive abrasion of brittle materials. A rounded edge prevents observation of the true thickness; this is usually prevented by an additional coating applied before mounting, but removal of coating material during preparation for it lowers the result. Optimum etching gives a narrow dark line at the boundary of two metals, excessive etching — a wide and indistinct line. Smearing of metal during improper polishing or by a coating of a softer metal obscures the boundary. The magnification is chosen so that the field of view is 1.5 to 3 times the coating thickness. The length standard (stage micrometer) shall be metrologically traceable; the micrometer eyepiece is calibrated by the person who measures, the spacing of the stage micrometer lines must be known to within 0.2 µm or 0.1 % (whichever is greater), some image-splitting eyepieces have a non-linearity of up to 1 %, and backlash is eliminated by always finishing the movement of the hairline in the same direction. With digital image analysis, the µm/pixel conversion factor is determined on the stage micrometer for each combination of objective, magnification changer and camera setting and checked periodically (e.g. with a limit of 1 %). Uniformity of magnification across the field of view, the quality of the objectives and a constant tube length between calibration and measurement also matter.

MEASUREMENT, UNCERTAINTY, REPORT (clauses 7–9). The microscope and the measuring device are calibrated with a certified or calibrated stage micrometer, and the width of the image of the coating cross-section is measured at at least five points distributed along the cross-section. The microscope, its calibration and the preparation of the cross-section are chosen so as to determine the thickness to within 1 µm or 10 % of the true thickness (whichever is greater); the method allows an absolute uncertainty of 0.8 µm, for thicknesses over 25 µm — 5 % or better, and with careful preparation and suitable instruments — 0.4 µm. Report: reference to ISO 1463:2021, identification of the test specimen, location of the cross-section, thickness at each point (in µm, above 1 mm — in mm), local thickness as the arithmetic mean, deviations, unusual observations, date.

EDITIONS. The fourth edition ISO 1463:2021 (ISO/TC 107 in collaboration with CEN/TC 262) replaced ISO 1463:2003; according to the foreword, digital image analysis in light microscopes and further guidance on preparing cross-sections were added, and one hazardous etchant recipe was removed from Annex C. In the iTeh catalogue (read on 27.10.2026) ISO 1463:2021 has the status "Published" and the stage "9060 – Close of review", and EN ISO 1463:2021 — "Published".

STATUS (PKN card as of 27.10.2026). The card of PN-EN ISO 1463:2021-10 (English version) has no withdrawal label: publication 21-10-2021, 24 pages, Metallurgy Sector, KT 106 Corrosion and Corrosion Protection of Metallic Materials, "Adopts: EN ISO 1463:2021 [IDT], ISO 1463:2021 [IDT]", "Replaces: PN-EN ISO 1463:2006 - Polish version", ICS 25.220.20 and 25.220.40. PKN search, search term "ISO 1463" (27.10.2026): the editions PN-EN ISO 1463:1997, 2004 and 2006 are withdrawn; there is no Polish version of the 2021 edition in the results — the current standard is available only in English.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database refreshed from the production server on 27.10.2026 and current PCA documents downloaded on that day). Number 1463 appears in 12 records at 6 Polish laboratories: AB 053 (7 records — in the PCA document this is one bilingual entry), AB 089, AB 128, AB 342, AB 1489, AB 1700. The standard is in all 6 current PCA documents; no entry is suspended. Forms: "PN-EN ISO 1463:2021-10" (AB 053, AB 089, AB 342, AB 1489, AB 1700) and "PN-EN ISO 1463" without the year (AB 128). AB 053 has the standard in one cell with metallographic standards (PN-H-04504, PN-H-04517, PN-H-04661, PN-EN ISO 945-1, PN-H-04505) and its own instruction IP-BLM-07; at AB 342 the asterisk means, according to the PCA document, tests on the basis of whose results the laboratory formulates opinions and interpretations. The "Laboratories" tab ("PN-EN ISO 1463") shows 22 laboratories: these 6 Polish ones and 16 Czech ones (tab query on labcoda.pl, 27.10.2026).

WHAT THE LABORATORIES TEST (database copy and PCA documents). Metallic and oxide coatings (AB 342, optical microscopy; AB 053 in metal products and materials), construction products and materials (AB 1489, microscopical method), organic and inorganic coatings on metal and plastic products (AB 128 — together with PN-EN ISO 2808 method 6A), metals, plastics, composites, polymers and paint coatings (AB 089 — together with PN-EN ISO 2808:2020-01 method 6A), organic (paints, varnishes) and inorganic (metallic, oxide) coatings on ferromagnetic and non-ferromagnetic substrates in the range 0–2000 µm (AB 1700 — together with PN-EN ISO 2808:2020-01 method 6A).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — scope: ISO 1463 concerns metallic coatings, oxide layers and enamels; paint (organic) coatings lie outside it — which is why three laboratories give method 6A of standard PN-EN ISO 2808 alongside for them. Second — inclination of the cross-section and of the measuring line: every 10° of deviation from the perpendicular contributes 1.5 % uncertainty, and an inclined cross-section always overstates the thickness. Third — edge of the coating: without support (additional coating or mounting without a gap) the edge becomes rounded and the true thickness cannot be seen; on the other hand, removal of coating material during preparation for the additional coating lowers the result. Fourth — etching: too strong etching gives a wide, indistinct boundary and an erroneous measurement. Fifth — calibration: the µm/pixel factor is valid only for the objective, changer and camera setting for which it was determined; the micrometer eyepiece is calibrated by the person measuring. Sixth — the result is the local thickness (mean of at least 5 points on one cross-section), not the mean thickness of the whole product.

WHAT WE DO NOT GIVE. The fragment of ISO 1463:2021 we read ends at the beginning of Annex A (A.2.2). We do not give the further guidance of Annex A (grinding, polishing, etching), Annex B (inclination of the cross-section, coatings with a serrated structure) or the compositions of the etchants from Annex C.

Method principle

A piece of the coated test specimen is cut out, mounted, ground, polished and etched so as to obtain a flat cross-section perpendicular to the coating with clear boundaries; the width of the image of the coating cross-section is measured under an optical microscope with a calibrated scale (micrometer eyepiece or digital image analysis calibrated with a stage micrometer) at at least five points along the cross-section, and the local thickness is their mean (ISO 1463:2021, clauses 4, 6–7).

Applications

• Metallic coatings, oxide layers, porcelain and vitreous enamels — local thickness on a cross-section (ISO 1463:2021, clause 1)
• Destructive method: a piece is cut from the product, and the result refers to the location of the cross-section, which the report states (clauses 4 and 9)
• In accreditation scopes: 6 Polish laboratories — metallic and oxide coatings, metal and construction products; at three of them method 6A of PN-EN ISO 2808 for paint coatings alongside

Key parameters

Standard

Standard number

PN-EN ISO 1463:2021-10 (wersja angielska; wprowadza EN ISO 1463:2021 i ISO 1463:2021 [IDT])

Title (PL)

Powłoki metalowe i tlenkowe — Pomiar grubości powłoki — Metoda mikroskopowa

Title (EN)

Metallic and oxide coatings — Measurement of coating thickness — Microscopical method

Step-by-step procedure

1. Cutting and mounting

   Piece of the test specimen cut out and mounted; the free surface of the coating is supported by an additional coating (similar hardness, ≥ 10 µm) or by mounting without a gap (clause 4, Annex A.2).

2. Cross-section

   Grinding, polishing, etching: cross-section perpendicular, flat, without a deformed layer, with clear coating boundaries (clause 6).

3. Calibration

   Microscope and measuring device — with a stage micrometer; magnification with a field of view of 1.5–3 × the thickness (points 5.8, 7.2).

4. Measurement

   Width of the image of the coating cross-section at at least 5 points along the cross-section, with a line perpendicular to the boundaries (points 5.13, 7.3).

5. Result and report

   Thickness at each point (µm), local thickness as the mean, location of the cross-section, deviations, anomalies, date (clause 9). PN-EN ISO 1463:2021-10 — current (PKN card as of 27.10.2026; English version).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The standard warns that its use may involve hazardous materials, operations and equipment (warning before clause 1) — this applies particularly to etchants
• TECHNICAL NOTE: paint coatings are not within the scope of ISO 1463 — for them method 6A of PN-EN ISO 2808

Frequently asked questions