1. The short version

• Antimicrobial action is not a property of a material; it is a result under test conditions. A recent paper reports that for the same contact-killing coating, changing only the test broth moved the reduction in microbes from 0.4–3.5 log to more than 5 logSourced [Source 9]. Copper lost antibacterial and antifungal efficacy at low humidity [Source 2]
• Corrosion protection combines barrier, sacrificial action and inhibitors. Hexavalent chromium inhibits both anodic and cathodic reactions and rebuilds a protective film at damage (self-healing), so a like-for-like replacement has not been established so farSourced [Source 10]
• Salt spray testing can serve for pass/fail decisions, but not for predicting life. A study comparing 19 coatings for hydraulic steelwork in the neutral salt spray test (ISO 9227) with five years of outdoor and immersion exposure found a correlation in only 6 of 12 comparisons, and coatings without a zinc primer passed in the laboratory but failed outdoorsSourced [Source 15]

This article concentrates on mechanisms and on how to read evaluations. Antimicrobial action of photocatalytic titanium dioxide is in our explainer on titanium dioxide and photocatalysis; how to read self-healing evaluations in our explainer on self-healing materials and vitrimers; microcapsules in our explainer on microcapsules; the definition and regulation of nanomaterials in our explainer on nanomaterial definitions and regulation; and anti-fouling of ships in our explainer on superhydrophobic, anti-icing and anti-fouling coatings.

2. A map of antimicrobial mechanisms — silver, copper, zinc oxide and photocatalysts, quaternary ammonium

(1) Silver — silver ions, more than particles

Xiu et al. conclude that the toxicity of silver nanoparticles (AgNPs) comes from released silver ions (Ag⁺). When AgNPs were synthesised and tested under strictly anaerobic conditions, which prevent Ag⁺ release, they showed no toxicity, and the dose-response of AgNPs of different sizes and coatings followed that of Ag⁺ (added as AgNO₃). Moreover, at low (sublethal) concentrations (3–8 μg/L Ag⁺, 12–31% of the minimum lethal concentration), survival of E. coli was stimulated (a hormetic-type response), which they note would be counterproductive to antimicrobial applicationsSourced [Source 3]. The review by Dakal et al. states that the size, shape, surface charge, concentration and colloidal state of AgNPs affect antimicrobial activity, and that action is through several mechanisms (adhesion to and penetration of cells, generation of reactive oxygen species, modulation of signal transduction). The same review notes that AgNPs cause cytotoxicity, genotoxicity and inflammatory responses in human cells, depending on cell type [Source 4].

(2) Copper — contact killing on dry metal, and the effect of humidity

The review by Grass et al. calls the rapid death of bacteria, yeasts and viruses on metallic copper “contact killing”, and gives a killing rate of at least 7 to 8 logs per hour, with no live microorganisms generally recovered after prolonged incubationSourced [Source 1]. Cunliffe et al. (2026), on the other hand, say that moisture is often overlooked in standard test methods. They developed a method that places small droplets (ten 1 μL droplets) on copper (and inert stainless steel) and recovers the microbes while the droplets are still wet and 2 hours after they have dried. With this method copper showed decreased antibacterial and antifungal efficacy at low relative humidity, while high antiviral efficacy was kept. The same paper states that current standards sometimes use conditions far from the end-use environment, such as relative humidity above 90%, and that a test with constant moisture can overemphasise the efficacy of some materials; copper surfaces can pass standards such as ISO 22196 because water is available throughout the test [Source 2].

(3) Zinc oxide and photocatalysts — reactive oxygen species

The review by Sirelkhatim et al. states that the antibacterial action of zinc oxide nanoparticles (ZnO-NPs) depends on particle size, concentration, morphology, defects, surface modification and ultraviolet illumination. As mechanisms it names generation of reactive oxygen species (such as H₂O₂ and hydroxyl radicals), cell-wall damage, increased membrane permeability and uptake of dissolved zinc ionsSourced [Source 5]. For photocatalysts such as titanium dioxide, there are separate standards that evaluate antibacterial activity by the number of microbes under ultraviolet light (ISO 27447, JIS R 1702), covered in our explainer on titanium dioxide and photocatalysis.

(4) Quaternary ammonium — action on the cell membrane, and resistance

Quaternary ammonium compounds (QACs) have been used for about a century as disinfectants whose main action is to disrupt the cell membrane and lyse the cell. The review by Jennings et al. says that QACs were once thought to be immune to resistance, but that qac genes encode efflux pumps that lower susceptibility to QACs, and that these genes can be transferred horizontally on plasmids and are often carried together with antibiotic-resistance genesSourced [Source 7]. The review by Hegstad et al. likewise states that resistance to QACs is widespread among diverse microorganisms and that evidence of co-resistance and cross-resistance with other antibiotics and disinfectants is increasing [Source 8].

As an example of immobilisation on a surface, Tiller et al. sprayed an aqueous suspension of bacteria (Staphylococcus aureus) onto glass slides to which poly(4-vinyl-N-alkylpyridinium bromide) was covalently attached, and let them dry; depending on the alkyl chain, up to 94 ± 4% of the cells were killed. On surfaces modified with N-hexylated poly(4-vinylpyridine), viable cells of other bacteria (S. epidermidis, Pseudomonas aeruginosa, E. coli) dropped by more than 100-fold compared with the original amino glass. Under the same conditions, viable cells did not decline significantly on ceramics, plastics, metals and woodSourced [Source 6].

3. Evaluating antimicrobial action — test conditions change the result

ISO 22196:2011 and JIS Z 2801 are used to evaluate antibacterial activity on plastics and other non-porous surfaces (a paper lists ISO 22196, ASTM E2180 and JIS Z 2801 side by side as the same kind of test [Source 9]). ISO 22196:2011 specifies a method for evaluating the antibacterial activity of antibacterial-treated plastics and other non-porous product surfaces. Its scope excludes textile products (ISO 20743) and photocatalytic materials (ISO 27447), and it is not to be used to document biodegradability or secondary effects such as the prevention of biodeterioration and odourSourced [Source 20].

A recent paper states that for regulatory compliance and efficacy testing, only three variants of the required standard testing method — ISO 22196, ASTM E2180-18 and JIS Z 2801 — are in practice used; they are simple, affordable and ideal for screening, but the choice of conditions has a large effect on the resultSourced [Source 9].

The “Examples confirmed” column is Sourced (van Agtmaal et al. [9], Cunliffe et al. [2], the official ISO page [20]). The last row is commentary by this article.

4. Ideas of corrosion protection — barrier, sacrificial, active

Ways of limiting corrosion of metals can be organised into three broad ideas (this article’s grouping).

View the original SVG schematic and exact annotations

• Barrier: a coating that is slow to pass water, oxygen and chloride ions separates the substrate. If there is a scratch or defect, corrosion advances from that spot
• Sacrificial: cover the steel with a metal more electrochemically active than it (zinc), so that the zinc dissolves first and protects the steel. Bolsanello et al. studied, with scanning electrochemical techniques (SECM and SVET) in simulated acid rain, the localised electrochemical reactions at the cut edge of zinc-alloy-coated steel (ZnAlMg-galvanized steel) between the exposed steel and the more active coatingSourced [Source 11]
• Inhibitor (active protection): build a corrosion-inhibiting component into the coating so that it acts on damage. Chromate is the representative case (Section 5), and designs that store the inhibitor in containers also exist (Section 6)

Bolsanello et al. report that cut edges strongly promoted oxygen consumption and alkalisation (pH 10–11) over the iron, with later depletion of oxygen neutralising the nearby electrolyte; that a thinner coating intensified the cathodic activation of the exposed iron despite the lower amount of sacrificial anode; and that the corners showed localised acidification below pH 4 that sustained hydrogen evolution at spots of the steel–coating interface [Source 11] (these results are for ZnAlMg-galvanized steel in simulated acid rain). ISO 1461:2022 specifies the general properties and test methods of hot dip galvanized coatings applied by dipping fabricated iron and steel articles in a zinc melt containing not more than 2% of other metals. It does not apply to continuously galvanized sheet, wire and mesh, or tube and pipe galvanized in automatic plantsSourced [Source 23]. For electroplated zinc there is ISO 2081:2025, which covers zinc coatings with supplementary treatment in solutions containing hexavalent chromium [Source 24].

5. Chromate-free — why the “two-sided inhibition and self-healing” of hexavalent chromium is hard to replace

According to the review by Gharbi et al. (npj Materials Degradation, 2018), hexavalent chromium (Cr(VI)) films are defined by exceptional versatility, remarkable corrosion protection and cost-effectiveness. Chromates are both anodic and cathodic inhibitors, restricting both metal dissolution and the reduction of oxygen and water. When a coating or primer develops a defect, chromate ions (CrO₄^2-) leach into the electrolyte and the “active sites”, are cathodically reduced and form a protective chromium oxide (Cr₂O₃) film, which is poorly soluble across the pH range and adherent to the metal — a barrier that repairs damage by itselfSourced [Source 10].

The same review states that a “universal” replacement compound has not yet been identified, and organises the main alternatives as follows [Source 10].

All Sourced (Gharbi et al. [Source 10]). The statements are those of a 2018 review; later progress was not checked.

6. Conducting polymers, and self-healing anti-corrosion coatings

(1) Conducting polymers — a proposed “protection zone” mechanism

Conducting polymers (ICPs) such as polyaniline and polypyrrole have become key materials in the search for high-performance coatings that protect metals from corrosion. Merz, Uebel and Rohwerder used dedicated model samples and Kelvin-probe measurements to find that disconnected ICP particles in composite coatings on iron and zinc inhibit oxygen reduction in their vicinity, creating a “protection zone” where no or only very slow delamination occurs. The mechanism relies on the ICP’s high potential and redox activity, and its efficiency may depend on the ICP type, thickness and counter-anionSourced [Source 12].

This is an analysis of a mechanism on model samples, and it does not show the life of an actual coated product. Anti-corrosion by conducting polymers is a field in which the mechanisms (protection of the anode, suppression of oxygen reduction and so on) are still discussed, and this article keeps to one proposed mechanism confirmed in a primary source (a note by this article). Conducting polymers in general are covered in our explainer on conducting polymers and ionic conductors.

(2) Self-healing anti-corrosion coatings — stored in containers, released on damage

Habib et al. loaded halloysite nanotubes (HNTs) with a corrosion inhibitor (NaNO₃) and urea–formaldehyde microcapsules with a healing agent (linseed oil), added them to a polymer coating and applied it to polished mild steel. They report that inhibitor was released from the HNTs over time in response to pH change, that the coating showed “decent” self-healing against controlled mechanical damage, and that electrochemical impedance spectroscopy (EIS) indicated promising anti-corrosion performanceSourced [Source 13]. The review by Poornima Vijayan and Al-Maadeed (2019) organises the extrinsic strategies for self-healing anti-corrosion coatings and the methods of evaluating them (accelerated salt immersion test, EIS, the scanning vibrating electrode technique SVET and scanning electrochemical microscopy SECM) [Source 14].

A 2024 review states that an established standard method for assessing the efficiency of self-healing in coatings does not yet exist (assessments divide into visual and quantitative methods)Sourced [Source 16]. How to read this is covered in our explainer on self-healing materials and vitrimers.

7. Testing corrosion protection — salt spray matches outdoor results only in part

ISO 9227:2022 specifies the apparatus, reagents and procedure for the neutral salt spray (NSS), acetic acid salt spray (AASS) and copper-accelerated acetic acid salt spray (CASS) tests, for assessing the corrosion resistance of metallic materials with or without permanent or temporary corrosion protection. However, the standard does not specify the exposure period for a particular product, the dimensions or types of specimens, or the interpretation of results; such details are given in the appropriate product specifications. The salt spray tests are described as particularly useful for detecting discontinuities such as pores and other defects in metallic, organic, anodic oxide and conversion coatingsSourced [Source 27].

Schmid (2024) compared 19 organic coatings for hydraulic steelwork in the neutral salt spray test (ISO 9227), in mechanical-property tests, and in five years of outdoor exposure at four locations in the atmospheric, splash and immersion zones. The results were as followsSourced [Source 15].

• No correlation was found between the mechanical properties of a coating and its anti-corrosion performance in outdoor exposure
• The NSS test correlated with the field results in 6 of 12 cases (half). At the fresh-water site (Trier) the correlation proved very good
• The biggest difference between laboratory and field was for coatings without a zinc primer, which passed in the laboratory and failed outdoors
• Even so, the results of NSS testing can be useful as approval testing with predefined pass/fail criteria

In other words, salt spray is not a tool for saying “N hours means M years“. As cyclic corrosion tests that alternate wetting and drying there are ISO 11997-1:2026 (one of four defined wet (salt fog)/dry/humid cycles) [Source 28] and JIS K 5600-7-9 (cyclic corrosion test method: salt spray/dry/wet), but these too are not predictors of outdoor life and are one means of evaluation (a note by this article).

For electrochemical evaluation of coatings, electrochemical impedance spectroscopy (EIS) has the ISO 16773 series, whose Part 1 gives terms and definitionsSourced [Source 29].

8. Regulation — the Biocidal Products Regulation (BPR) and hexavalent chromium: proposal, adoption and application kept apart

(1) The EU Biocidal Products Regulation (BPR) and “treated articles”

Regulation (EU) No 528/2012 (dated 22 May 2012, applying from 1 September 2013) governs the making available on the market and use of biocidal products. A biocidal product is a substance or mixture consisting of, containing or generating one or more active substances, intended to destroy, deter, render harmless, prevent the action of or otherwise exert a controlling effect on any harmful organism by any means other than mere physical or mechanical action. A treated article that has a primary biocidal function is considered a biocidal product. A treated article is any substance, mixture or article which has been treated with, or intentionally incorporates, one or more biocidal productsSourced [Source 19].

For treated articles that are not biocidal products (such as products given an antimicrobial finish), Article 58 provides that all active substances contained in the biocidal products used for treatment must be approved for the relevant product-type and use (with any conditions met) before the article may be placed on the market. It also requires labelling where the manufacturer claims biocidal properties, among other cases (a statement that the article incorporates biocidal products, the names of the active substances, and, for nanomaterials, the word “nano” in brackets), and requires the supplier to give a consumer who asks information on the biocidal treatment free of charge within 45 daysSourced [Source 19]. One of the product-types (product-type 21) is “antifouling products”, used to control the growth and settlement of fouling organisms on vessels, aquaculture equipment or other structures used in water [Source 19].

Which product-types each active substance (silver, copper compounds, zinc compounds, quaternary ammonium and so on) is approved for was not checked in this article. Also, what this article checked is the text published in the Official Journal in 2012, and later amendments were not checked.

(2) Hexavalent chromium — REACH authorisation, RoHS restriction

Commission Regulation (EU) No 348/2013 (dated 17 April 2013) added to Annex XIV (the authorisation list) of REACH, as entries 16 to 22, chromium trioxide, acids generated from chromium trioxide, and sodium, potassium and ammonium dichromate, potassium chromate and sodium chromate. For every entry the latest application date is 21 March 2016 and the sunset date is 21 September 2017Sourced [Source 17]. Gharbi et al. state that chromium compounds are restricted unless authorised by the European Chemicals Agency (ECHA) and that authorisations are limited in time [Source 10]. The content and current status of authorisations for individual uses were not checked in this article.

Annex II of the RoHS Directive (2011/65/EU, dated 8 June 2011) sets, as the maximum concentration by weight in homogeneous materials of electrical and electronic equipment, hexavalent chromium 0.1% (lead 0.1%, mercury 0.1%, cadmium 0.01% and others). Annex III lists exemptions, one example being hexavalent chromium as an anticorrosion agent of the carbon steel cooling system in absorption refrigerators (up to 0.75% by weight in the cooling solution). The deadline for Member States to transpose it was 2 January 2013Sourced [Source 18] (the text as published; later amendments were not checked).

9. Limits, and what could not be confirmed

(1) Conditions in the papers’ bodies

For Xiu et al., Dakal et al., Sirelkhatim et al., Tiller et al., Jennings et al., Hegstad et al., Merz et al., Habib et al. and Poornima Vijayan et al., this article relied on abstracts (the review by Gharbi et al. was read in its main sections; Schmid and Cunliffe et al. are also abstract-level). Strains, broths, test times and concentrations should be checked in each paper.

(2) Persistence of antimicrobial action, and performance after use

Antimicrobial performance after washing, abrasion and ultraviolet exposure, the life of release types (reservoir and release rate) and effects in actual use were not checked. Effects on humans and the environment (the behaviour of silver ions, zinc and quaternary ammonium in the environment) are not covered and are not generalised.

(3) Scope of regulation

For the BPR, the text as published was checked and amendments were not. The approval status of individual active substances, the content of individual REACH authorisations, the latest amendments and exemptions of RoHS, and regulation in Japan, the United States and China were not checked.

(4) Standards

The texts of ISO, JIS and ASTM standards were not checked. Corresponding IEC and IEEE standards, and a standard method of evaluating the efficiency of self-healing anti-corrosion, could not be confirmed. For ASTM standards on zinc coatings, because the ASTM website is not opened, no non-ASTM source giving a number and title was found, so they could not be confirmed.

(5) Items not covered

Details of conversion treatment of aluminium and magnesium alloys, anodising, metallic coatings other than plating (such as thermal-sprayed aluminium), anti-fouling of ships (our explainer on superhydrophobic, anti-icing and anti-fouling coatings) and antimicrobial action of photocatalysts (our explainer on titanium dioxide and photocatalysis) are not covered.

10. How to read evaluations and standards

Antimicrobial evaluation inoculates treated and untreated specimens with microbes, incubates them under fixed conditions, compares viable counts and expresses antimicrobial activity as the difference (such as a log reduction). Corrosion evaluation uses rust, blistering and mass loss after salt spray or wet/dry cycles, electrochemical impedance (EIS), and the results of outdoor and immersion exposure. What standards define is the method of each test; they do not give pass criteria or performance for “antimicrobial” or “anti-corrosion”.

Numbers and titles of ISO standards were checked on the official ISO pages and those of JIS on the JIS search of the Japanese Industrial Standards Committee (JISC); JIS titles are our translation of the Japanese titles. For ASTM standards, the ASTM website was not opened; numbers and titles were checked only through statements in peer-reviewed papers and their reference lists. The ASTM column gives no test content, conditions or acceptance criteria. The arrangement of the table is Our calculation.

Where each standard sits — international, national, trade body

• ISO standards are international, JIS standards are Japanese national, and ASTM standards are issued by a US standards organisation. ISO 22196, JIS Z 2801 and ASTM E2180 are listed together as the same kind of test in a paper [Source 9], but the degree of agreement among them (identical, modified and so on) was not confirmed because the bodies of the standards were not checked
• ISO 11997-1 is the 2026 edition (fourth edition), ISO 2081 the 2025 edition (fifth edition), and ISO 9227 the 2022 edition (fifth edition, with one amendment). ISO 22196 is the 2011 edition (second edition), confirmed in 2026. Even for the same number, a different edition can mean a different procedure
• ISO 27447 is marked due for revision (“to be revised”), and so is ISO 12944-2

Cautions when reading

• A standard is a “test method” and does not guarantee a material’s performance. “99.9% antibacterial according to ISO 22196” is a result under that test’s conditions and does not mean the effect in the use environment or against other microbes
• The same named property can be measured differently depending on the standard or edition. Antibacterial activity has separate standards for plastics (ISO 22196), textiles (ISO 20743) and photocatalysts (ISO 27447). Values from different standards cannot be compared directly
• Read manufacturer values together with the standard, edition and test conditions they followed. “N hours of salt spray” goes with the coating thickness, the presence of a scratch, the substrate of the panel and the pass criterion. ISO 9227 does not specify the exposure period or the interpretation of results [Source 27]
• Watch the gap between the range of a standard and real service conditions. Standard methods fix conditions for reproducibility [Source 2]. How results shift under real humidity, washing, soil and environment cannot be known from a standard alone

11. Glossary

12. References (primary sources)

1. Grass G., Rensing C., Solioz M. “Metallic Copper as an Antimicrobial Surface”, Appl. Environ. Microbiol. 77, 1541–1547 (2011), DOI 10.1128/AEM.02766-10 — doi.org/10.1128/aem.02766-10
2. Cunliffe A. J. et al. “Assessing antibacterial, antiviral, and antifungal efficacy of non-porous materials using small droplet transfer: the simulated splash method”, Appl. Environ. Microbiol. 92, e02304-25 (2026), DOI 10.1128/aem.02304-25 (open access) — doi.org/10.1128/aem.02304-25
3. Xiu Z. et al. “Negligible Particle-Specific Antibacterial Activity of Silver Nanoparticles”, Nano Lett. 12, 4271–4275 (2012), DOI 10.1021/nl301934w — doi.org/10.1021/nl301934w
4. Dakal T. C. et al. “Mechanistic Basis of Antimicrobial Actions of Silver Nanoparticles”, Front. Microbiol. 7, 1831 (2016), DOI 10.3389/fmicb.2016.01831 (open access) — doi.org/10.3389/fmicb.2016.01831
5. Sirelkhatim A. et al. “Review on Zinc Oxide Nanoparticles: Antibacterial Activity and Toxicity Mechanism”, Nano-Micro Lett. 7, 219–242 (2015), DOI 10.1007/s40820-015-0040-x (open access) — doi.org/10.1007/s40820-015-0040-x
6. Tiller J. C., Liao C.-J., Lewis K., Klibanov A. M. “Designing surfaces that kill bacteria on contact”, Proc. Natl. Acad. Sci. USA 98, 5981–5985 (2001), DOI 10.1073/pnas.111143098 — doi.org/10.1073/pnas.111143098
7. Jennings M. C., Minbiole K. P. C., Wuest W. M. “Quaternary Ammonium Compounds: An Antimicrobial Mainstay and Platform for Innovation to Address Bacterial Resistance”, ACS Infect. Dis. 1, 288–303 (2015), DOI 10.1021/acsinfecdis.5b00047 — doi.org/10.1021/acsinfecdis.5b00047
8. Hegstad K., Langsrud S., Lunestad B. T. et al. “Does the Wide Use of Quaternary Ammonium Compounds Enhance the Selection and Spread of Antimicrobial Resistance and Thus Threaten Our Health?”, Microb. Drug Resist. 16, 91–104 (2010), DOI 10.1089/mdr.2009.0120 — doi.org/10.1089/mdr.2009.0120
9. van Agtmaal J. et al. “Test parameter selection affects the perceived antibacterial efficacy of a contact-killing coating developed to prevent prosthetic joint infection”, Front. Bioeng. Biotechnol. 14 (2026), DOI 10.3389/fbioe.2026.1854828 (open access; only the comparison of test conditions is used, and the medical assessment is not covered) — doi.org/10.3389/fbioe.2026.1854828
10. Gharbi O., Thomas S., Smith C., Birbilis N. “Chromate replacement: what does the future hold?”, npj Mater. Degrad. 2, 12 (2018), DOI 10.1038/s41529-018-0034-5 (open access) — nature.com/articles/s41529-018-0034-5
11. Bolsanello M. et al. “Contributions to a More Realistic Characterization of Corrosion Processes on Cut Edges of Coated Metals Using Scanning Microelectrochemical Techniques, Illustrated by the Case of ZnAlMg-Galvanized Steel with Different Coating Densities”, Materials 17, 1679 (2024), DOI 10.3390/ma17071679 (open access) — doi.org/10.3390/ma17071679
12. Merz A., Uebel M., Rohwerder M. “The Protection Zone: A Long-Range Corrosion Protection Mechanism around Conducting Polymer Particles in Composite Coatings: Part I. Polyaniline and Polypyrrole”, J. Electrochem. Soc. 166, C304–C313 (2019), DOI 10.1149/2.0971912jes — doi.org/10.1149/2.0971912jes
13. Habib S. et al. “Self-Healing Performance of Multifunctional Polymeric Smart Coatings”, Polymers 11, 1519 (2019), DOI 10.3390/polym11091519 (open access) — doi.org/10.3390/polym11091519
14. Poornima Vijayan P., Al-Maadeed M. “Self-Repairing Composites for Corrosion Protection: A Review on Recent Strategies and Evaluation Methods”, Materials 12, 2754 (2019), DOI 10.3390/ma12172754 (open access) — doi.org/10.3390/ma12172754
15. Schmid R. “Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure”, Corros. Mater. Degrad. 5, 490–512 (2024), DOI 10.3390/cmd5040023 (open access) — doi.org/10.3390/cmd5040023
16. Panahi, Khorasani, Mensah “A review of the characterization methods for self-healing assessment in polymeric coatings”, Prog. Org. Coat. 186, 108055 (2024), DOI 10.1016/j.porgcoat.2023.108055 (the content of the abstract was checked through a European Coatings news summary) — doi.org/10.1016/j.porgcoat.2023.108055
17. European Commission “Commission Regulation (EU) No 348/2013 of 17 April 2013 amending Annex XIV to Regulation (EC) No 1907/2006 (REACH)”, OJ L 108, 18.4.2013 (Publications Office of the EU) — publications.europa.eu/resource/celex/32013R0348
18. European Parliament and Council “Directive 2011/65/EU of 8 June 2011 on the restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS)”, OJ L 174, 1.7.2011 (Publications Office of the EU) — publications.europa.eu/resource/celex/32011L0065
19. European Parliament and Council “Regulation (EU) No 528/2012 of 22 May 2012 concerning the making available on the market and use of biocidal products”, OJ L 167, 27.6.2012 (Publications Office of the EU) — publications.europa.eu/resource/celex/32012R0528
20. ISO “ISO 22196:2011 Measurement of antibacterial activity on plastics and other non-porous surfaces” — iso.org/standard/54431.html
21. ISO “ISO 20743:2021 Textiles — Determination of antibacterial activity of textile products” — iso.org/standard/79819.html
22. ISO “ISO 27447:2019 Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for antibacterial activity of semiconducting photocatalytic materials” — iso.org/standard/69874.html
23. ISO “ISO 1461:2022 Hot dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods” — iso.org/standard/81435.html
24. ISO “ISO 2081:2025 Metallic and other inorganic coatings — Electroplated coatings on iron and steel using zinc treated with solutions containing chromium (VI)” — iso.org/standard/88302.html
25. ISO “ISO 9223:2012 Corrosion of metals and alloys — Corrosivity of atmospheres — Classification, determination and estimation” — iso.org/standard/53499.html
26. ISO “ISO 12944-2:2017 Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 2: Classification of environments” — iso.org/standard/64834.html
27. ISO “ISO 9227:2022 Corrosion tests in artificial atmospheres — Salt spray tests” — iso.org/standard/81744.html
28. ISO “ISO 11997-1:2026 Paints and varnishes — Determination of resistance to cyclic corrosion conditions — Part 1: Wet (salt fog)/dry/humid” — iso.org/standard/87280.html
29. ISO “ISO 16773-1:2016 Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens — Part 1: Terms and definitions” — iso.org/standard/64794.html
30. Japanese Industrial Standards Committee (JISC) JIS search, JIS Z 2801 (Antibacterial products — Test for antibacterial activity and efficacy; title in Japanese) — jisc.go.jp (Z2801)
31. Japanese Industrial Standards Committee (JISC) JIS search, JIS L 1902 (Testing for antibacterial activity and efficacy on textile products; title in Japanese) — jisc.go.jp (L1902)
32. Japanese Industrial Standards Committee (JISC) JIS search, JIS R 1702 (Fine ceramics — Test method for antibacterial activity of photocatalytic materials and efficacy; title in Japanese) — jisc.go.jp (R1702)
33. Japanese Industrial Standards Committee (JISC) JIS search, JIS Z 2911 (Methods of test for fungus resistance; title in Japanese) — jisc.go.jp (Z2911)
34. Japanese Industrial Standards Committee (JISC) JIS search, JIS H 8641 (Hot dip zinc coatings; title in Japanese) — jisc.go.jp (H8641)
35. Japanese Industrial Standards Committee (JISC) JIS search, JIS H 8610 (Electroplated zinc coatings; title in Japanese) — jisc.go.jp (H8610)
36. Japanese Industrial Standards Committee (JISC) JIS search, JIS Z 2371 (Methods of salt spray testing; title in Japanese) — jisc.go.jp (Z2371)
37. Japanese Industrial Standards Committee (JISC) JIS search, JIS K 5600-7 (Testing methods for paints — Part 7: Long-term durability of film; Section 1 neutral salt spray resistance, Section 6 outdoor exposure weathering, Section 9 cyclic corrosion test method; titles in Japanese) — jisc.go.jp (K5600-7)
38. Japanese Industrial Standards Committee (JISC) JIS search, JIS Z 2381 (General rules for atmospheric exposure testing; title in Japanese) — jisc.go.jp (Z2381)
39. Publicly available papers used to confirm ASTM numbers and titles (the ASTM website was not consulted): E2180 in Molecules 31, 137 (2025), DOI 10.3390/molecules31010137 / E2149 in J. Funct. Biomater. 14, 524 (2023), DOI 10.3390/jfb14100524 / B117 in Heliyon (2024), DOI 10.1016/j.heliyon.2024.e40681 / G85 in Materials 17, 2304 (2024), DOI 10.3390/ma17102304 / G106 in Sci. Rep. (2024), DOI 10.1038/s41598-024-64323-x — doi.org/10.3390/molecules31010137 (and others)

13. Claim-to-source audit

Last updated 10 October 2026. Sources are limited to primary material (peer-reviewed papers, EU acts in the Official Journal and standards-body pages). Many papers were checked only to the extent of their abstracts, and the test conditions in the body were not checked for some of them. Because the article includes structural readings and materials-design interpretations, those are marked as Commentary and kept separate from sourced fact. The BPR approval status of individual active substances, the individual content of REACH authorisations, the content of the regulations and the directive after amendment, antimicrobial action after washing and abrasion, and ASTM standards for zinc coatings could not be confirmed and are not stated here. The antimicrobial and anti-corrosion figures are results under fixed conditions in the laboratory and cannot be generalised to other materials or real use. They are not a guarantee of “safe” or “completely prevents”. All figures are explanatory concept graphics. Figs. 2 to 5 and 7 are vector drawings; Figs. 1 and 6 are AI-generated images, and none of them shows a real micrograph, experimental data or physical product.