Anticorrosive Pigments Research Articles

The effect of nanoporous silica aerogel on corrosion protection properties of epoxy coatings on carbon steel

In this paper, due to special properties of aerogels such as ultra-low density and hydrophobic nature of aerogels, this nanomaterial was used as anticorrosive pigments. Silica aerogel was dispersed in epoxy resin by using sonication method. The dispersion of nanoparticles were characterized by transmission electron microscopy. The anticorrosive properties of these coatings were investigated by salt-spray and electrochemical impedance spectroscopy methods in a 3.5 wt % NaCl solution. Impedance parameters showed a decrease in coating resistance over immersion time. Results indicated that epoxy coatings containing nano silica aerogel could significantly increase the corrosion resistance of composite coatings compared to those of pure epoxy and the highest value was obtained for 0.5% aerogel nanocomposite coatings after 160 days immersion. Pull off adhesion test showed the highest value of adhesion was related to coating containing 0.5% aerogel. According to salt-spray methods, it was found that the best results were obtained with coatings containing 0.5 and 1 wt % of silica aerogel.

The anticorrosion properties of pigments based on molybdates and tungstates surface-modified with conducting polymers

AbstractThe objective of this work was to examine the properties of molybdate or tungstate based pigments whose surface has been coated with a conductive polymer, viz. either polyaniline phosphate (PANI) or polypyrrole phosphate (PPY), if used as pigments in organic coating materials. The anticorrosion pigments were prepared by high-temperature solid-state synthesis from the respective oxides, carbonates. The composite pigments (pigment/conductive polymer) were dispersed in a solvent-type epoxy-ester resin binder to obtain a series of paints whose anticorrosion properties were assessed by means of corrosion tests in accelerated corrosion test and by the linear polarisation method. Focus was on the anticorrosion properties of the paints depending on the pigment surface treatment, initial pigment composition, and pigment volume concentration (PVC) in the paint. The surface-treated pigment particles were expected to have a favourable effect on the anticorrosion and the mechanical properties of epoxy-ester resin based paints.

One step self-heating synthesis and their excellent anticorrosion performance of zinc phosphate/benzotriazole composite pigments

Zinc phosphate/benzotriazole (ZPB) corrosion pigments were synthesized by one step self-heating method. The ZPB pigments showed visible anticorrosion performance by enhancing the corrosion resistance of the epoxy coating effectively through electrochemical impedance spectroscopy test. The impedance activity of ZPB pigments was increased by 1275.5% and 196.5% compared to pure zinc phosphate (ZP) and benzotriazole (BTA) pigments, respectively. The super effect of anticorrosion mostly contributed to the one step self-heating method, which improved the stability of the pigments and reinforced the combination of pigments and epoxy coating by the plank martensite structure of ZPB pigment. This method could transfer the heat released during the synthesis of ZP to the dissolving of BTA by directly co-precipitation, realizing the heat of self-sufficient in one step. Moreover, ZPB pigments achieved complementary anticorrosion effect, for making up the loopholes of the single anticorrosion and achieving superior property in the initial of anticorrosion process. It is instructive for the synthesis and development of the anticorrosive pigment in the future.

Study on Self-Healing Film Formed on the Cut Edge of Prepainted 55%Al-Zn Steel Sheet with Anti-Corrosion Pigments

Study on Self-Healing Film Formed on the Cut Edge of Prepainted 55%Al-Zn Steel Sheet with Anti-Corrosion Pigments

塗膜下腐食のテラヘルツ波非接触計測における表面散乱評価

Two dimensional reflection intensity distributions of terahertz wave intensity provide a direct transparent image of corrosion beneath opaque anticorrosion paint layers. However, attention needs to be paid to changes in effective reflectivity due to uneven surfaces. This study demonstrates in-situ estimation of surface roughness and reflective index by frequency analysis of the terahertz wave form reflection echoes. Deconvolution technique is applied to resolve the undulation of the waveform to separate the overlapping of the reflections from the front and back surfaces of the paint. Estimated and measured roughness values are in good agreement, to show roughness and refractive index distribution of a service-used transmission tower cross-arm.

Development of Nanostructured Polymer-Immobilized Anti-Corrosion Barrier-Type Materials, Applied and Operated in Adverse Conditions

Development of modern high-end coatings is a challenge. At this point, the problem of the range and quality of corrosion-resistant materials is one of the most serious in the Russian paint industry. The article deals with some aspects of obtaining anticorrosive materials, applied and operated in adverse conditions. Binder and solvents were selected, were found the optimal working concentration of the film-forming solution, were selected conditions of dispersing. Also was selected anticorrosion pigment, were studied its surface properties, the optimal concentration was chosen.

Electrochemical Investigations of the Corrosion Protection Properties of an Epoxy-Ester Coating Filled with Cerium Acetyl Acetonate Anticorrosive Pigment

The corrosion inhibition properties of cerium acetyl acetonate (CeAA) in solution phase were studied by various electrochemical techniques including electrochemical noise (EN), electrochemical impedance spectroscopy (EIS) and polarization test. The EIS and EN tests results demonstrated effective corrosion inhibition properties of cerium acetyl acetonate in solution phase on mild steel. Polarization test results revealed that the CeAA could inhibit both anodic and cathodic reactions. The partial solubility of CeAA in the 3.5 wt% NaCl solution resulted in the formation of active Ce3+ cations and cerium acetyl acetonate anions which adsorbed and formed inhibitive films based on cerium oxide/hydroxide on the cathodic regions and Fe2+-cerium acetyl acetonate complex on the anodic sites. Moreover, the EIS results revealed that incorporation of CeAA pigment into epoxy-ester coating provided good corrosion-protective performance. Not only the barrier performance but also the active inhibition properties of the coating were improved in the presence of CeAA pigment.

Assessment of the properties of diethyl phosphite as a novel anticorrosion pigment in organic coatings

The aim of this work was to provide a first description of the behaviour of diethyl phosphite in organic coatings, description of their physico-mechanical properties as well as anticorrosion properties in the protection of steel substrates. The diethyl phosphite behaviour in the organic coatings depends on the volume concentration of the pigment. A polyaniline base was suspended in diethyl phosphite as a new reactant. The pigment so prepared was used as a corrosion inhibitor in model paints containing a solvent-based epoxy-ester resin as the binder. The organic coatings were applied to steel panels and to glass panels and subjected to mechanical tests, corrosion resistance tests and electrochemical tests. Furthermore, they were exposed to the environments of condensed steam, neutral salt solution mist, and sulphur dioxide-containing mist. The corrosion effects were evaluated and the organic coatings’ overall anticorrosion efficiency was calculated from the results. Ultimately, the optimum pigment volume concentration (PVC) at which the coatings provided the best anticorrosion protection was determined: it was PVC = 10 vol%, whereas the best mechanical resistance was observed at PVC = 5 vol%. The goal of the forthcoming work will be to optimise all the properties into a single pigment volume concentration.

Protective properties of paint and lacquer coatings based on a fluorine-containing film-forming material

Paint and lacquer coatings (PLCs) are most commonly used when one needs to impart an aesthetic appeal to metal surfaces and protect them from the effects of the environment. Priming paint and lacquer compositions, which are dispersions of anticorrosion pigments in film-forming materials possessing a high adhesion to the surface that is being coated, are rather widespread among the variety of paint and lacquer corrosion- protection materials. The use of a fluorine-containing film-forming material to produce a PLC is rather promising. In this work, we have studied the protective properties of coatings that are based on epoxy varnish and a fluorine-containing polymer and filled with chromate and chromate-free anticorrosion pigments. The protective properties of PLCs have been evaluated by express tests in a salt spray chamber. The PLC structure has been analyzed by scanning-electron and atomic-force microscopy.

Heteropolyacids like new anticorrosion pigment in organic paints

Abstract This paper is focused on the heteropoly acids as another new possibility of dopant for conducting polymers which can be used as anticorrosive pigments for steel protection. The newly prepared pigments, silicotungstic and phosphotungstic heteropoly acids, were characterized by determination of oil number and density. The value of critical pigment volume concentration was determinated by these values. The pigment volume concentration was 0.5; 1; 3 and 5 % in epoxyester-resin witch was used as a binder. Organic coatings were applicated on steel panels which were tested by mechanical and corrosion tests. The main exam was exposition of testing sample in sulphur dioxide atmosphere. Another important exam was measuring the specific electrical conductivity and determination of corrosion loss. After 1584 hours, the samples were evaluated. Values of anticorrosion efficiency are increased for silicotungstic heteropoly acid pigment. But with long-term exposition, phosphotungstic heteropoly acid pigment has better and higher anticorrosion efficiency than the other sample.

Improvement in polyurethane coating performance through zinc aluminium phosphate pigment

Purpose This research aims to provide a comparative study of the effect of conventional zinc phosphate (ZP) and zinc aluminium phosphate (ZPA) representing second generation of phosphate-based anticorrosion pigments on the protective performance and physical mechanical properties of a solvent-borne polyurethane (PU) coating. Design/methodology/approach The two pigments were incorporated into the coating at optimum pigment volume concentration. To evaluate the protective performance, electrochemical impedance spectroscopy (EIS) was used. The effect of modification of ZP on the physical–mechanical properties of the coatings was studied through dynamic mechanical thermal analysis. Moreover, Micro Vickers hardness and pull-off tests were used to evaluate the hydrolytic coating degradation. Findings EIS revealed the superior protective function of coatings incorporated with ZPA compared to those formulated with ZP. This behaviour might be attributed to the release of sufficient inhibiting species because of partial dissolving of the anticorrosive pigments when an electrolyte penetrates into the coating. In addition, the effectiveness of modification of ZP on the physical–mechanical properties of coatings was shown. Research limitations/implications As a classical replacement for the toxic chromates, ZP has been widely used in the formulation of protective coatings. However, undesirable inhibitive function of the pigment arising from its low solubility has made modification necessary. Because of the modified solubility, second generation of phosphate-based anticorrosion pigments has been reported to reveal superior performance. Originality/value According to the literature, no report can be found studying the effect of the second generation of phosphate-based anticorrosion pigments on the physical–mechanical properties of PU coatings. The main goal of this work is to study the correlation between physical–mechanical properties and anticorrosion performance of the PU coatings.

Introducing rice husk after utilizing new technology as anticorrosive pigments in organic coatings

Abstract The aim of this study is to introduce rice husk after simple chemical modification as new eco-friendly anticorrosive pigments. Uncontrolled burning of rice husk is often considered the most disposal method in Egypt; this seasonal and highly localized massive burning generates excessive air pollution. The usage of this waste as anticorrosive pigments will decrease the danger of environment pollutions. The new anticorrosive pigments based on rice husk as core comprising 80–85% of new pigment covered with thin shell of ferrites that comprises about 15–20% were prepared using new technique called “core-shell”. The different ferrites/rice husk pigments were characterized using different analytical and spectro-photometric techniques, such as X-ray fluorescence (XRF), Energy dispersive X-ray (EDAX) and transmission electron microscopy (TEM). These core-shell pigments were then incorporated in solvent-based paint formulations based on epoxy resin. The physico-mechanical properties of dry films were tested. The corrosion properties using immersion test in 3.5% NaCl and electrochemical impedance spectroscopy (EIS) for 28 days were determined.

A Smart-Release Corrosion Inhibitor Pigment for Galvanised Steel Based on Salicylaldoxime-Loaded Hydrotalcite

Smart-release anticorrosion pigments are a promising alternative technology to traditional anticorrosive pigments such as sparingly soluble salts. Due to legislation prohibiting the use of chromium (VI) containing protective coatings, new environmentally friendly alternatives are required. Smart release pigments have numerous advantages over traditional pigment technologies. Sparingly soluble salts slowly leach out their constituent ions over time, which both reduces the lifetime of the coating and leads to environmental effects. In contrast, smart release pigments utilise ion-exchange properties to release inhibitor species on demand, whilst simultaneously sequestering corrosive species such as chloride ions. In this work intelligent release pigments based on anion-exchange hydrotalcite (HT) like materials were studied with respect to their efficiency in the inhibition of cathodic disbondment of a model coating. The ability of the various organic-anion loaded HT pigments to inhibit cathodic delamination of hot dip galvanised steel was evaluated using polyvinyl butyral (PVB) coatings containing a range of volume fractions of the inhibitive pigments. An in-situ Scanning Kelvin Probe (SKP) technique was used to measure the rate of delamination over time, by measuring time-dependent changes in free corrosion potential of the zinc surface under the organic coatings. Of the selection of organic anions evaluated, the most effective corrosion inhibitor was found to be salicylaldoxime, a well-known chelating reagent for various divalent metal cations. The slowing of cathodic delamination rates with increasing pigment volume fraction compared well with the performance of a hexavalent chromate-containing benchmark. To determine the importance of the release of salicylaldoxime from the coating into the electrolyte in contact with bare metal at a penetrative coating defect, experiments were also conducted using unpigmented PVB coatings in a situation where inhibitor additions were made to the initiating electrolyte. The conclusion of this investigation is that for the corrosion protection of galvanised steel surfaces, salicylaldoxime-loaded HT intelligent-release pigments represent effective, yet environmentally friendly alternatives to the current chromate containing coating technologies.

Preparation, Characterization and Electrochemical Study of Lanthanum-Silica Sol-Gel Thin Films

This work presents a low cost environmentally friendly alternative to corrosion protection of aluminium alloy based on silica sol-gel thin films doped with lanthanum compounds. Sols were prepared from solutions composed of tetraethylorthosilicate and methyl-triethoxysilane as precursors, distilled water to perform the hydrolysis, absolute ethanol as solvent and nitric acid as catalyst. Lanthanum acetate hydrate or lanthanum isopropoxide in three different concentrations were added as doping agents. These lanthanum compounds can play as the well-known Cr (VI) salts offering a suitable protective effect without any environmental negative impact. L-cysteine as green corrosion inhibitor has been also added to a set of sol formulations. Films were deposited upon microscope glass slides and aluminium alloy AA2024-T3 sheets by dip coating at a constant drawing speed (2.0 mm·s−1), in a controlled room under 25°C and 35% relative humidity. For convenience, sol-gel monoliths of 20 mm diameter were also prepared. After coating, monoliths and films were dried and annealed in air at 20, 100 and 500 °C. A model polyvinyl butyral film was applied on a series of these sol-gel coatings to simulate the performance of commercial anticorrosive paints (organic coatings). For this matter poly (vinyl butyral-covinyl alcohol-co-vinyl acetate) solutions (17% w/w) were prepared in ethanol. Transmission spectra of the as prepared films were recorded with a UV–VIS-NIR double-beam spectrophotometer equipped with an integrating sphere. Optical measurements (from UV-Vis absorption and diffuse reflectance spectroscopies) pointed out that the coatings were colourless and transparent, and they diminish the diffuse reflectance of the metallic surface up to ∼60 %. Scanning electronic microscopy coupled with energy dispersive spectroscopy (SEM-EDS), atomic force microscopy (AFM) and contact angle measurements were also applied for the coatings characterization. As concerns the structural characterization of the lanthanum environment X-ray Absorption Fine Structure (XANES) and X-ray Absorption Near Edge Structure spectroscopy (EXAFS) were also performed. Likewise, the remaining sols were kept to gelify at 60 °C for 4 days and then powdered to obtain suitable samples to be analysed by using other characterisation techniques (Fourier transformed infrared, FTIR, and differential thermal analysis, DTA). The corrosion resistance of the sol-gel coated AA2024-T3 aluminium alloy was studied by weathering tests according to modified ISO 1776 and 695 Standards. Samples were immersed into an acid solution (HCl 0.1 N at 25 °C) or into a basic one (NaOH 0.1 N at 25°C) for 1 h. In parallel studies, anodic and cathodic delamination tests were also carried out during immersion of coated samples into a 0.6 M NaCl aqueous solution. Just before the experiment was initiated, the centre of the PVB/sol-gel thin film/metal samples was damaged with an intentionally scribed linear defect. Potentiodynamic polarization technique and global and electrochemical impedance spectroscopy were also applied. The results show that the presence of lanthanum compounds and L-cystiene induces an effective delay of early corrosion of metallic substrates, demonstrated by accelerated corrosion tests in acid and basic media. XAS studies confirmed the incorporation of lanthanum ions into silica sites to be essential for the material anticorrosive properties. Optical and scanning electron microscopies allowed the coated samples texture and microstructure observation, both before and after the corrosion tests were carried out. These last two techniques joined with the electrochemical studies allowed to evaluate not only the inhibitor effect of lanthanum compounds and L-cysteine, but also the self-healing properties of the studied systems. As concluding remarks, we may indicate the convenience and effectiveness of the prepared sol-gel silica films doped with lanthanum isopropoxide or lanthanum acetate as a protective barrier for the delay of early corrosion of metallic surfaces. These properties are scarcely dependent on the lanthanum precursor used, which could be selected taking in mind the corresponding cost. Depending on the reaction parameters in the sol-gel process, La2O3 or La(OH)3 nanoparticles can be intentionally produced. The combination of these La2O3 nanoparticles with L-cysteine produces a synergic effect which improves considerably the corrosion protection behaviour of sol-gel coated AA2024-T3 aluminium alloy in NaCl aqueous solutions. The uniformly distributed La2O3 or La(OH)3 nanoparticles impregnated with corrosion inhibitor behave as active fillers and nanoreservoirs for the sol-gel thin film, providing a prolonged and smart release of the corrosion inhibitor (L-cysteine) in response to local pH changes during the samples contact with the aqueous solutions. The action of the organic inhibitor combined with the precipitation of insoluble lanthanum products from the inorganic framework at the cathodic and anodic corrosion zones, provides self-healing properties to the protective system, avoiding the corrosion processes as expected. Acknowledges: This work was supported by MINECO, Spain (Projects MAT2012-38541-C02-02, MAT2015-65445-C2-1-R and MAT2015-65445-C2-2-R).

An Investigation of Zinc Based Polyphosphates As Corrosion Inhibitors for Use in Organically Coated Steel

Strontium chromate has long been the industrial standard for corrosion inhibition in organically coated steels (OCS) but legislation will ban its use from 2017due to its carcinogenic properties. Research is focused on sourcing a suitable replacement to strontium chromate. Results indicate that no replacement fully matches the corrosion inhibition performance.. Zinc phosphate is the leading replacement and has shown promising corrosion inhibition performance but cannot match the effectiveness of chromate in organic coatings (1) (2) (3). The poor performance of zinc phosphate has led to research into polyphosphate-based corrosion inhibitors which have shown promising results (4) (5). Ongoing studies at Swansea University have shown that a range of polyphosphate-based inhibitors demonstrate an effective corrosion-inhibition on galvanised steel. The polyphosphates, supplied by Heubach Ltd, are widely used throughout the coating industry. In-situ scanning Kelvin probe (SKP) technique has proven the ability of polyphosphates to stall and resist cathodic delamination. The technique is further utilised to investigate the effect of various weightings of polyphosphates in model coatings of polyvinyl butryal (PVB). It is thought that the various cations incorporated within the polyphosphates will improve the precipitation layer that is typical in corrosion inhibition for zinc phosphate. The corrosion products were analysed using SEM, EDX and XPS which allows for further evaluation of the corrosion mechanisms that govern the corrosion-inhibition. Current theories attribute the inhibition to electrochemical and mass-transport blocking effect. Further work has shown how polyphosphates perform within an industrial coating. The salt spray technique (ASTM B117-11) has been used to evaluate the performance of industrial coatings containing a range of polyphosphates perform compared to strontium chromate and zinc phosphate. 1. The mechanism of inhinition by zinc phosphate in an epoxy coating. Yongheng Hao, Fuchun Liu, En-Hou Han, Saima Anjum, Guobao Xu. 2013, Corrosion Science, Vol. 69, pp. 77-86. 2. Characterisation of barrier properties of organic paints: the zinc phosphate effectiveness. M.Beiro, A.Collazo, M.Izquierdo, X.R. Novoa, C. Perez. s.l. : Progress in Organic Coatings, 2003, Vol. 46. 3. Comparative electrochemical studies of zinc chromate and zinc phosphate as corrosion inhibitors for zinc phosphate as corrosion inhibitors for zinc. A.C.Bastosm, M.G.S. Ferreira, A.M. Simoes. 4, s.l. : Progress in Organic Coatings, 2005, Vol. 52. 4. the inhibitive performance of polyphosphate-based anticorrosion pigments using electrochemical techniques. R.Naderi, M.M. Attar. 80, s.l. : Dyes and Pigments, 2009. 5. An organic coating pigmented with strontium aluminium polyphosphate for corrosion protection of zinc alloy coated steel. Yanwen Liu, Xiaorong Zhou, Stuart B. Lyon, Reza Emad, Teruo Hashimoto, Ali Gholinia, George E. Thompson, Derek Graham, Simon R. Gibbon, David Francis. s.l. : Progress in Organic Coatings, 2016.

An Svet Study of the Throwing Power of Smart-Release Corrosion Inhibitor Pigments in Organic Coatings

An SVET study of the throwing power of smart-release corrosion inhibitor pigments in organic coatings Ion-exchanged anti-corrosion pigments phenylphosphonic acid, benzotriazole and 5-methylbenzotriazole exchanged in hydrotalcite (HT) are studied in terms of ‘throwing power’ when dispersed in a model polyvinyl-butyral (PVB) primer coating adherent to a hot dip galvanised steel substrate. The Scanning vibrating electrode technique (SVET) is used in a novel study to determine the inhibitory effects of the primer coatings when fully immersed in 5% w/v NaCl electrolyte. Samples are prepared as shown in Figure 1 where a coated sample is insulated such that only the edges of the protective coating and a defined area of bare metal are exposed to electrolyte. Current density mapping of the exposed area is carried out over a 24 h period. HT has been shown previously to reduce cathodic delamination, by moderation of under coating pH, reduce chloride activity and also release ionic inhibitors[1]. In the presence of a penetrating electrolyte, effective inhibition is achieved through the leaching of anions creating an insoluble blocking layer[2] [3]. The current study enables the isolation of the leaching mechanism. By systematically altering distance x, the extent to which inhibitors are able to leach into the bulk electrolyte and stifle corrosion can be mapped, allowing a threshold to be determined. Figure 1. Sample set-up showing coated hot dip galvanised steel surface with exposed scan area.

The use of electrochemical impedance spectroscopy with segmented electrodes to study inhibition at the cut-edge of coil-coated systems

Abstract The use of multiple metal segmented electrodes has been applied to study the inhibition mechanisms for several anti-corrosion pigments that are commonly used in organic coatings. The relatively novel experimental methodology involves, firstly, polarisation of the coupled metal system at the common coupled potential but with the currents on the separated electrodes recorded individually and, secondly, the application of electrochemical impedance spectroscopy at the same coupled potential. For example, at the cut-edge of a coil-coated galvanised steel sheet, electrochemical data may be gathered simultaneously at an anodic potential for the zinc and at a cathodic potential for the steel substrate. Using this methodology the inhibitive efficiency for strontium chromate, calcium ion-exchanged silica and zinc molyphosphate inhibitors were determined under the electrochemical condition expected in service.

Synergism in anticorrosive paints

The present work depicts synergism anticorrosive behaviour between zinc hypophosphite and zinc phosphate in a commercial pigment mixture. Also, the performance of anticorrosive paints was evaluated. Synergism anticorrosive behaviour was evaluated by corrosion potential and linear polarization measurements in pigment suspensions. The protective layer obtained with this pigment mixture was investigated by scanning electron microscopy (SEM). Then, the anticorrosive properties of the pigment were assessed by incorporating it into alkyd and epoxy paints which were evaluated by salt spray test and electrochemical noise technique. The morphology and the nature of the protective layer grown under the paint film were also studied by SEM. Experimental results showed that improved anticorrosion protection is achieved in paints with reduced zinc phosphate contents as a consequence of the synergistic interaction between zinc hypophosphite and the other components of the pigment mixture. The electrochemical noise technique proved to be adequate to monitor corrosion in painted panels and is able to detect corrosion under the paint film from very early stages. This paper identified the need to study synergism between anticorrosive pigments to try to reduce the phosphate content in anticorrosive paints.

Theoretical study of the corrosion protection mechanism by carbon nanotubes

The paint corrosion protection mechanism has been studied by density functional B3LYPGD3/6-31G(d,p) method using Gaussian09 program. The quantum-chemical study demonstrates the growth of anti-corrosion paint properties by the addition of carbon nanotubes (CNT) in the coating composition. Quantum chemical calculations have shown that the carbon nanotubes have a high affinity to the particles that support corrosion process (anions, oxygen molecules, hydroxyl groups). Thus, CNTs act as the adsorbents of particles that support the corrosion process.

The best tests for anti-corrosive paints. And why: A personal viewpoint

This paper starts by putting forward a mechanism for the way that anti-corrosive paints work. This draws on previous work on understanding of mechanism but puts stronger emphasis on the maintenance of the oxide film of the metal under the paint as the essential feature. If this mechanism is correct then it suggests various properties which a paint coating should have. In many cases a minimum value of these properties is all that is required. In some cases e.g. DC resistance, it is advantageous to have as high as possible value of this property at the start due to degradation with time. The paper then details a series of tests, chosen by the authors for their relative simplicity, to measure these properties in a quantitative manner and hence to assist in formulation of new or better coatings. These tests are the personal selection of the authors and we admit that others may make different choices. They have been divided into those best conducted on the free paint film and those which are conducted on the metal and paint together, the latter including one test to be conducted on the metal alone. Among the second group, suggestions have been made for electrochemical tests which are non-destructive and can thus be used for quality control and monitoring. There is a brief discussion of accelerated tests with the emphasis again on quantitative non-destructive assessment methods. Numerous pertinent references are provided. The papers concludes with suggestions for future work.