Guide for Materials 

Selection and Design for 

Metals Used in Contact 

with Copper-Treated 

Wood 

Samuel L. Zelinka

Forest

Products

Laboratory

General

Technical 

Report

FPL–GTR–227

United States Department of Agriculture

Forest Service

In cooperation 

with the

United States

Department of

Transportation

Federal 

Highway 

Administration
August 2013

Zelinka, Samuel L. 2013. Guide for materials selection and design for metals used in contact with copper-treated wood. General Technical Report 

FPL-GTR-227. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 12 p.

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Abstract

This design guide summarizes recent research on the corrosion of metals in treated wood, presents design strategies to 

minimize corrosion of metals in contact with treated wood, 

and is targeted toward engineers, architects, builders, and 

homeowners. The guide is organized as a “question and 

answer” document. While the questions are arranged in a 

logical order, each question and answer are self-contained. 

Special efforts have been made to provide a comprehensive 

bibliography to direct the reader to further information on 

each question. The document was created to give practical 

“hands-on” information for corrosion in treated wood.

Keywords: corrosion, fasteners, galvanized steel, carbon 

steel, preservative-treated wood, alkaline copper quaternary 

(ACQ), chromated copper arsenate (CCA), copper azole

Contents

Introduction........................................................................1

What Is Corrosion? ............................................................1

What Is Treated Wood? What Types of Wood 

Preservatives Are Used? ....................................................2

Why and How Do Metals Corrode in Treated Wood? .......3

How Rapidly Do Metals Corrode in Wood?......................5

Do Wood Extractives Affect Corrosion?............................6

How Does the Corrosion of Fasteners Affect the 

Strength of the Connection? ..............................................7

How Can I Design To Minimize Corrosion in Treated 

Wood? ................................................................................8

 Moisture Management ....................................................8

 End Grain.......................................................................9

 Roof................................................................................9

 Coated Metals ................................................................9

 Mixed Metals.................................................................9

References........................................................................11

This study is part of the Research, Technology and 

Education portion of the National Historic Covered 

Bridge Preservation (NHCBP) Program administered 

by the Federal Highway Administration. The NHCBP 

program includes preservation, rehabilitation and restoration of covered bridges that are listed or are eligible 

for listing on the National Register of Historic Places; 

research for better means of restoring, and protecting 

these bridges; development of educational aids; and 

technology transfer to disseminate information on covered bridges in order to preserve the Nation’s cultural 

heritage.

This study is conducted under a joint agreement between the Federal Highway Administration–Turner 

Fairbank Highway Research Center, and the Forest 

Service – Forest Products Laboratory.

Federal Highway Administration Program Manager– 

Sheila Rimal Duwadi, P.E.

Forest Products Laboratory Program Manager– 

Michael A. Ritter, P.E.
Guide for Materials Selection and Design 

for Metals Used in Contact with CopperTreated Wood

Samuel L. Zelinka, General Engineer

Forest Products Laboratory, Madison, Wisconsin

Introduction

The corrosion of metals in contact with wood has been 

studied for over 80 years, and in most situations wood is 

not corrosive. Recently, however, concerns have been raised 

about the durability of fasteners in preservative-treated 

wood. These concerns are a result of changes in regulation 

and certification of certain wood preservatives in the United 

States, the European Union, and Australasia. These regulation changes brought new copper-based wood preservatives 

into the market, following which was anecdotal evidence 

suggesting that newer wood preservatives were more corrosive (Mittendorf 2009), but little testing or scientific understanding to make informed decisions. Since this regulation 

change, there has been much research in this area.

This paper represents a compilation of research on the corrosion of metals in treated wood and is intended to explain 

why metals corrode in treated wood and give practical 

design recommendations. While the paper is targeted for 

a non-scientific audience, it is based upon experimental 

evidence. These experiments are cited throughout the document and further scientific details can be found in the references in the bibliography. The paper is arranged topically by 

questions. Although each question builds upon the previous 

question, the content within each question is independent, 

so the paper does not need to be read from cover to cover if 

only a specific question needs to be answered.

What Is Corrosion?

Corrosion is an oxidation/reduction reaction where a metal 

is oxidized (loses electrons) and a nearby chemical species 

is reduced (gains electrons). Once oxidized, the metal ion 

quickly reacts with the environment to form an inorganic 

compound (i.e., “rust”) (Fig. 1). Except for a few precious 

metals, such as gold and platinum, corrosion is nearly always thermodynamically favorable and will spontaneously 

happen. Therefore, materials selection is not about selecting 

materials that will not corrode (which is nearly impossible), 

but rather about selecting materials that will corrode so 

slowly that that the metal remains functional throughout 

its service life.

Frequently when a metal corrodes, it forms a protective 

oxide or hydroxide layer that greatly reduces the corrosion 

rate of the remaining metal. This phenomenon is called passivation. Certain metals, such as aluminum and stainless 

steels, have extremely stable oxide layers that account for 

their corrosion resistance. In general, the stability of the passive layer depends upon the environment and is one of the 

controlling factors of the reaction kinetics, and therefore the 

useful service life of materials in a given environment.

Common metals used in combination with wood are carbon 

steel, galvanized steel, and stainless steel. Depending on 

how the metals are used, the metals are susceptible to 

several different types of corrosive attack. For example, 

Figure 2 shows the corrosion of a galvanized joist hanger 

held with galvanized nails and illustrates the different types 

of corrosion that can occur. The head of a nail or the outer 

side of a joist hanger is susceptible to atmospheric corrosion. The corrosion of the nail shank embedded in the wood 

depends upon the wood moisture content and chemistry. The 

inner face of the wood is similar to the embedded fastener 

but also may exhibit galvanic corrosion if the joist hanger 

and the fastener are made from different materials. Galvanic 

corrosion is described further in the section “How Can I 

Design To Minimize Corrosion in Treated Wood?”

Figure 1. The omnipresence of corrosion: these corroded 

objects were found during a short walk. The rust, which 

appears reddish-brown, is an inorganic ceramic compound formed as part of the oxidation process.
General Technical Report FPL–GTR–227

2

What Is Treated Wood? What Types 

of Wood Preservatives Are Used?

Wood preservatives are chemicals that are injected into the 

wood to help the wood resist attack by decay fungi, mold, 

and/or termites. Waterborne wood preservatives are used in 

most cases where the wood may be in contact with humans 

or will be painted. While many different formulations of 

waterborne preservative treatments have been developed, 

only a few of these have been used commercially. Most of 

the commercial treatments contain cupric ions, which give 

treated wood its characteristic greenish-brown coloration 

(Fig. 3).

In 2004, EPA regulation changes in the United States restricted the use of chromated copper arsenate (CCA), which 

had previously dominated the preservative market for many 

years. Similar regulation changes happened in the European 

Union and Australasia. CCA can still be used in certain situations, specifically wood used in highway construction (excluding pedestrian bridges or hand railings). Since the regulation change, alternatives to CCA have been introduced 

to and now dominate the market. Lebow (2004, 2010) has 

summarized alternatives to CCA. A brief summary of the 

commercially important alternative wood preservatives is 

provided below. Although the formulations of the following 

wood preservatives are different from each other, they all 

have a higher percentage of copper than does CCA. This is 

important, as the corrosion mechanism involves the reduction of cupric ions from the preservative. Furthermore, the 

chromates and arsenates in CCA act as corrosion inhibitors 

(Zelinka and others 2007).

Alkaline copper quaternary (ACQ) is composed of copper 

oxide (67%) and 33% of a quaternary ammonium compound (DDAC—didecyldimethylammonium chloride or 

carbonate). When it was first commercially available, the 

quaternary ammonium compound was made with a chloride 

formulation but was later almost exclusively replaced with 

carbonate. Several formulations of ACQ have been commercialized and it can be treated with an amine or ammonia 

carrier.

Copper azole (CA) type-B and C are composed of ammine 

copper (96%) and an azole (4%). In CA type B, the azole is 

entirely comprised of tebuconazole. In type C, the azole is 

50/50 mixture of tebuconazole and propiconazole. Although 

copper azole contains a higher percentage of copper than 

ACQ, the retention required for above-ground use (Category 

U3; Anon 2007a) is lower, and therefore, the total amount of 

copper in the treated wood is less.

In addition to these preservatives standardized by the American Wood Protection Association, several commercially 

important preservatives have been introduced to the market 

by ICC-ES evaluation reports. These preservatives include 

“micronized” formulations of ACQ and CA, which have 

various trade names. In these formulations, soluble copper is 

not injected into the wood; rather solid copper, copper oxide, or copper carbonate is ground into submicron particles 

or “micronized” and suspended in solution prior to injecFigure 2. Corrosion of a galvanized joist hanger and 

galvanized nails supporting a wood deck treated with a 

copper-containing wood preservative.

Figure 3. (From left to right) Wood treated with MCQ, 

DDAC, and ACQ. Cupric ions from the wood preservative 

causes the dark coloration of the wood. Excess copper 

has deposited on the MCQ (green splotches) and the ACQ 

(along the end grain).
Guide for Materials Selection and Design for Metals Used in Contact with Copper-Treated Wood

3

tion. Several different formulations of these preservatives 

are covered by different ICC-ES evaluation reports. These 

formulations differ in the listed uses and required retentions, 

and have slight differences in the formulations, but in general require less copper than the nonmicronized counterparts.

A summary of the wood preservatives highlighting copper 

concentration is given in Table 1. The preservative composition is given in the second column and the above-ground 

retention needed to meet Use Category 3b for above-ground 

use according to AWPA U1 is given in column 3 (Anon 

2007c). The fourth column, calculated from the second and 

third columns, lists the amount of copper metal per volume 

of wood. Several studies have shown that as the copper concentration in the wood is increased, the corrosion of metal 

fasteners increases (Kear and others 2009; Zelinka and 

Rammer 2011).

Why and How Do Metals Corrode in 

Treated Wood?

The waterborne wood preservatives listed in Table 1 contain 

cupric ions, which are thermodynamically unstable in the 

presence of steel or zinc galvanized fasteners. The mechanism of corrosion in treated wood involves the transport of 

cupric ions through the wood to the fastener surface, where 

the cupric ions are reduced and the fastener (zinc or iron) is 

oxidized (Baker 1980, 1988; Zelinka and Stone 2011a). We 

illustrate this mechanism of corrosion in Figure 4.

For carbon steel and zinc-galvanized fasteners, the reduction 

of cupric ions is thermodynamically favorable and will 

occur, but how rapidly they corrode (the corrosion rate) 

needs to be determined empirically. The corrosion rate is 

determined by the slowest reaction step. In theory, the corrosion of embedded metals could be limited by the diffusion 

of ions to the metal surface (diffusion control), or conversely it could be limited by the electron transfer reaction at 

the metal surface (activation control). Several independent 

experiments have suggested that at high wood moisture contents, the reaction is activation controlled.

The corrosion of embedded metals is strongly dependent 

upon moisture content. When the wood is dry, embedded 

metals do not corrode (Baker 1980; Dennis and others 1995; 

Short and Dennis 1997). Short and Dennis (1997) characterized the dependence of the corrosion rate on the wood moisture content using electrochemical techniques. They found 

that the corrosion rate increased with moisture content until 

hitting a maximum corrosion rate near the fiber saturation 

point. Zelinka and others (2011) have used the data of Short 

and Dennis (1997) to predict the corrosion rate of galvanized steel in ACQ-treated wood as a function of moisture 

content, and this curve is given in Figure 5. The data show 

the importance of controlling the wood moisture content to 

reduce corrosion; the corrosion rate climbs from less than 

1 μm y–1 at 16% moisture content to more than 40 μm y–1

at 26% MC.

The corrosion of metals in treated wood involves the reduction of cupric ions in the preservative and is strongly related 

to the wood moisture content. The mechanism is quite different from atmospheric corrosion, where the amount of 

Table 1. Summary of some waterborne wood preservatives and above ground 

retentions highlighting the difference in copper concentration between 

preservatives. Data are combined from Anon (2007b) and Lebow (2010). 

Preservative Composition

Above ground 

retention 

(kg of preservative 

per m3

 of wood) 

Copper

concentration

(g of copper per 

m3 of wood) 

CCA 47.5% chromium trioxide 

34.0% chromium trioxide 

18.5% copper as copper oxide 

4 591 

ACQ 67% copper as copper oxide 

33% DDAC 

4 2,141 

CA-B 96.1% amine copper as Cu 

3.9% tebuconazole 

1.7 1,634 

CA-C 96.1% amine copper as Cu 

1.95% tebuconazole 

1.95% propiconazole 

1.0 961 

ESR-1721 (MCA-B) 96.1% amine copper as Cu 

3.9% tebuconazole 

1.0 961 

ESR-1721 (MCA-C) 96.1% amine copper as Cu 

1.95% tebuconazole 

1.95% propiconazole 

0.8 769 

ESR-1980 67% copper as copper oxide 

33% DDAC 

2.4 1,285 

ESR-2240 25/26 copper particles 

1/26 tebuconazole 

1.0 961 
General Technical Report FPL–GTR–227

4

corrosion depends upon the amount of humidity, chlorides, 

and sulphides in the local environment. Not surprisingly, 

these differences in corrosion mechanism result in different 

behavior of metals in treated wood as opposed to those exposed to atmospheric condition. Since many of the methods 

for protecting steel from atmospheric corrosion are often 

applied to wood fasteners by default, we highlight the two 

major differences between the two environments: (1) relative corrosion rates of different metals and (2) variation of 

corrosion rate with time.

It is common knowledge that galvanized steel has a longer 

life than uncoated steel when undergoing atmospheric 

corrosion. Zhang (2003) summarized the literature and 

found steel exposed to outdoor atmospheric conditions, on 

average, corroded 20 times faster than zinc. In atmospheric 

corrosion, galvanized steel forms smithsonite (ZnCO3), a 

protective, passivating corrosion product that slows further 

corrosion. Likewise in atmospheric corrosion, carbon steel 

forms goethite (α-FeOOH), also called “red-rust.” Zinc 

corrodes more slowly in atmospheric corrosion than steel 

because smithsonite is better at protecting zinc from further 

corrosion than goethite is at protecting steel (Zhang 2003). 

In environments where smithsonite is not stable, such as 

immersion in saltwater or in environments with volatile 

acetic and formic acids, zinc corrodes more rapidly than 

steel (Knotkova-Cermakova and Vlckova 1971; Zhang and 

others 1998). Zelinka and others (2010) examined the corrosion products that formed on fasteners exposed to treated 

and untreated wood using X-ray diffraction and did not find 

smithonsite. In the same study, they observed that zincgalvanized fasteners corroded more rapidly than uncoated 

steel fasteners.

During atmospheric corrosion, in many cases the corrosion 

rate decreases with time because of passivation. Empirically, 

the kinetics are described by

 ∆W = Ktn (1)

where ∆W is the change in weight, K is a constant (the 1-y 

corrosion rate), t is the time in years, and n is an exponent 

that controls the kinetics and describes passivation (Legault 

and Preban 1975). Observed values of n range from 0.35 to 

1 (Legault and Preban 1975; Legault and Pearson 1978). 

Figure 4. Mechanism of corrosion in treated wood. Cupric ions migrate through the wood 

to the metal surface where they are reduced as the fastener is oxidized.

Figure 5. Corrosion rate of galvanized steel in ACQ-treated wood as a function of moisture content constructed 

from the data of Short and Dennis (1997) and Zelinka and 

Rammer (2009). From Zelinka and others (2011).
Guide for Materials Selection and Design for Metals Used in Contact with Copper-Treated Wood

5

Corrosion of metals in wood is activation controlled (n = 1) 

and therefore exhibits a constant corrosion rate with time. 

This observation is supported by Baker (1992), who conducted a 17-y exposure test and observed that the mass loss 

increased linearly with time. Electrochemical corrosion testing performed by Zelinka and others (2008) also supports 

that the corrosion mechanism is activation controlled. They 

observed that the corrosion rate in water extracts of treated 

wood was the same as those measured in solid wood, which 

suggests that diffusion is not the rate limiting mechanism. 

Finally, comparison of measured diffusion rates of cupric 

ions in wood (1.3 cm y–1, Simons and others 1998) to the 

diffusion rate needed to maintain the measured corrosion 

rate of 60 μm y–1 (diffusion rate of <1 cm y–1), suggests that 

diffusion should not be the limiting factor.

In short, the corrosion mechanism involves the reduction of 

cupric ions, depends upon the wood moisture content, and is 

different from atmospheric corrosion. By understanding the 

corrosion mechanism, it is possible to develop strategies for 

maximizing the life of embedded fasteners. For example, by 

using a metal noble to copper (e.g., stainless steel), the fasteners are immune to the major corrosion mechanism. Likewise, if the wood can be kept dry, corrosion should not be a 

concern. A deeper examination of methods to protect wood 

from corrosion is given at the end of this document.

How Rapidly Do Metals Corrode in 

Wood?

Since the 2004 change in wood preservative regulation, 

there have been several investigations of the corrosiveness 

of metals in contact with treated wood. The studies cover a 

wide range of preservatives, preservative retentions, wood 

moisture contents, and metals tested. Not surprisingly, a 

wide variation in corrosion rates has been reported (e.g., 

from 2–113 μm y–1 for galvanized steel in ACQ-treated 

wood). Because of the wide variations of test conditions 

used, it is best to only compare results within a single study 

or across different studies with very similar conditions.

Many of the design recommendations for materials selection in wood are based off of the recommendations of Baker 

(1992), who conducted a 17-y investigation of corrosion of 

metal fasteners embedded into chromated copper arsenate 

(CCA) and ammoniacal copper arsenate- (ACA-) treated 

wood exposed either underground or in a room maintained 

near 100% relative humidity. From these data, Baker concluded that at a minimum, hot-dip galvanized fasteners 

should be used in treated wood and cautioned against the 

use of aluminum fasteners. Importantly, Baker presented 

the corrosion data as a percentage of weight loss instead 

of a true corrosion rate because he could not calculate the 

surface area of threaded fasteners. Zelinka and Rammer 

reanalyzed Baker’s data using data in Baker’s laboratory 

notebook and an algorithm they had developed to measure 

the surface area of threaded fasteners (Rammer and Zelinka 

2008; Zelinka and Rammer 2009; Rammer and Zelinka 

2010). They found that when the corrosion rate was adjusted 

to a true corrosion rate, the corrosion rate of aluminum 

was in fact less than hot-dip galvanized steel. Baker also 

reported that pitting was observed on the aluminum fasteners; however, Zelinka and Rammer could not determine 

any evidence of pitting corrosion in similar exposure tests 

conducted for one year, nor could they find any evidence of 

pitting corrosion in photographs in Baker’s laboratory notebook (Zelinka and Rammer 2009).

Zelinka has published results of several different corrosion 

tests that were conducted at 27 °C (80 °F) and 100% relative humidity (Zelinka 2007; Zelinka and Rammer 2009; 

Zelinka and others 2010; Zelinka and Stone 2011a). In one 

study, Zelinka and Rammer (2009) examined the corrosion 

of five different metal fasteners (carbon steel, hot-dip galvanized steel, electroplated galvanized steel, aluminum, and 

stainless steel) embedded in wood treated with ACQ-D to 

a retention of 4 kg m–3. They found that the corrosion rate 

of hot-dip galvanized steel (in μm y–1) was the highest (62) 

followed by carbon steel (34), aluminum (22), and electroplated galvanized steel (21).The corrosion rate of stainless 

steel was statistically indistinguishable from zero. In another 

study, Zelinka and others (2010) exposed steel and hot-dip 

galvanized steel fasteners to six different wood treatments: 

chromated copper arsenate (CCA-C), alkaline copper quaternary (ACQ-D), copper azole (CA-B), micronized copper 

quaternary (MCQ), didecyldimethylammonium carbonate 

(DDAC, or the “quat” in ACQ) and MCQ. For galvanized 

steel ACQ was the most corrosive (32 μm y–1), followed by 

CA (29), MCQ (19), CCA (16), DDAC (5.5), and untreated 

(4.4). For carbon steel, the order was slightly different: ACQ 

(17), MCQ (13), CA (11), CCA (10), DDAC (1.9), and untreated (0.7).

Kear and others (2009) examined the corrosion of three 

different metals (316 stainless steel, hot-dip galvanized 

steel, and plain carbon steel) in three different preservatives 

(CCA, ACQ, CA), treated to three different retention levels 

with four different test methodologies. The retention levels 

were specified in a New Zealand standard that specifies a 

mass basis (i.e., kg/kg) instead of a density basis and therefore cannot be directly compared to traditional U.S. retentions (in lb/ft3 or kg m–3). Differences in the corrosiveness 

of the preservatives were most apparent in a constant exposure to 90% RH. Corrosion rates were (CCA:CA:ACQ) 

4:14:45 μm y–1 for mild steel fasteners and 5:16:26 μm y–1 

for hot-dip galvanized steel fasteners. Average corrosion 

rates as high as 113 μm y–1 were observed for galvanized 

steel in ACQ-treated wood in a “moisture saturated air” 

condition.

Simpson Strong Tie Company (Pleasanton, California)

published a technical bulletin on the results of in-house 
General Technical Report FPL–GTR–227

6

AWPA E12 (Anon 2007a) corrosion tests they had conducted (Anon 2008). In this test method, a metal plate is 

sandwiched between two blocks of wood and exposed to a 

high temperature (50 °C), high humidity (90% RH) environment. They found that the corrosiveness of ACQ-D (carbonate) was roughly equivalent to that of CA, and both of these 

were more than twice as corrosive as CCA-C. They also 

found that ACZA was more than three times more corrosive 

than CCA and that borates were less corrosive than CCA. A 

footnote in the table mentioned that for micronized formulations like MCQ, the “relative corrosiveness is somewhat 

lower than ACQ-D.”

Copper napthenate is sometimes used as a preservative in 

timber bridges. Although there are no peer-reviewed data 

on the corrosiveness of copper napthenate, Anthony Forest Products Company (El Dorado, Arkansas) published a 

technical bulletin with the results of AWPA E12 tests that 

compares both the waterborne and oilborne formulations 

of copper napthenate against ACQ-D and CCA-C for mild 

steel, hot-dip galvanized steel, aluminum, and red brass 

(Anon n.d.). No data are given on the variability between 

replicates; however, the data clearly suggest that either formulation of copper napthenate is much less corrosive than 

ACQ and possibly less corrosive than CCA. For mild steel, 

the corrosion rates (in microns per year) were 124 for ACQ, 

25.4 for CCA, 4.3 for waterborne copper napthenate, and 

0.8 for the oilborne formulation. An even larger difference 

was observed for aluminum where the corrosion rates were 

185 for ACQ, 7.6 for CCA, 1.8 for waterborne copper napthenate, and 0 for the oilborne formulation. While it should 

be noted that this bulletin was published by a company that 

supplies products treated with copper napthenate, the data 

suggest that copper napthenate is much less corrosive than 

ACQ and less than or equal in corrosiveness to CCA.

Freeman and McIntyre (2008) summarized the results of 

several unpublished corrosion tests of pressure-treated wood 

in contact with different metals that compared traditional 

(ACQ and CA) against their micronized formulations (MCQ 

and mCA). Most of the data shown were from AWPA E12 

tests. The results are inconclusive. In one test, the micronized formulation of CA is less corrosive than the standard 

formulation for galvanized steel but more corrosive for plain 

carbon steel and the micronized formulation is much more 

corrosive to aluminum. The remainder of the E-12 data have 

similar trends; in some cases the micronized formulations 

show lower corrosiveness, in other cases, the traditional 

formulations appear less corrosive. The only results that 

consistently show that the micronized formulations are less 

corrosive than the traditional formulations are from a test 

conducted using a protocol from the International Staple and 

Nail Tool Association (ISANTA). In this test, the micronized formulations appear slightly (approximately 30%–40%) 

less corrosive, with the notable exception of aluminum, in 

which case the micronized formulations are more corrosive.

Table 2 summarizes corrosion rates measured in a variety of 

test methods over a range of wood preservatives and metals. 

Each row in the table represents a paper or report and the 

test method is briefly summarized in the leftmost column. 

Corrosion rates for each metal are contained in columns 

followed by the type of wood preservative. The data can be 

used for observing general trends or relative comparison of 

a preservative or a metal type; however, it is dangerous to 

compare across rows as different test methods were used.

Do Wood Extractives Affect 

Corrosion?

In addition to structural polymers (cellulose, hemicellulose, 

and lignin) wood contains a variety of additional chemical 

components. Because these chemicals can be extracted by 

rinsing with various solvents, they are referred to as extractives. The type and amount of extractives vary widely 

among wood species. In some species, called naturally durable species, the extractives can protect the wood from decay.

Although a single piece of wood can contain over 700 different extractives (Hazelwood and others 2006), only three 

types of extractives have been thought to affect the corrosion of metals in contact with wood or the black liquors of 

wood pulp: small organic acids (acetic and formic acid), tannins (or more broadly polyphenols), and phenols with two 

or three adjacent hydroxyl groups (e.g., catechol and pyrogallol). For solid wood, only organic acids and tannins have 

been mentioned in the literature; catechol (1,2-dihydroxybenzene) and pyrogallol (1,2,3-trihydroxybenze) are formed 

as the lignin is destroyed in the pulping process (Clark and 

Green 1968; Niemelä 1989). 

Although the pH of wood, a solid material, is not well 

defined, the water extracts of nearly all wood species are 

acidic (Packman 1960; Bootle 1983; Balban and Uçar 

2003). The reason for this acidity is that in the presence of 

water, acetyl and formyl groups in the hemicelluloses are 

hydrolyzed to form acetic and formic acid (Packman 1960). 

Research has shown that this process is chemical, rather 

than biological (Packman 1960) and that over 90% of the 

acid produced is acetic (Balban and Uçar 2003).

Zelinka and Stone (2011) have shown that the tannins in solid wood act as a corrosion inhibitor to the embedded fasteners. Previous research on sawblade corrosion suggested that 

wood tannins accelerated the corrosion of sawblades; however, in general, tannins are known as a corrosion inhibitor 

(Nasrazadani 1997; Matamala and others 2000; Mabrour 

and others 2004; Rahim and others 2008; Radojcic and others 2008). In addition to the corrosion rate data, Zelinka and 

Stone (2011b) observed a blue-black patina forming on the 

steel, indicative of the formation of iron-tannate (Fig. 6). 

Iron-tannate is known as a passivating corrosion product; as 

it is formed, it slows the corrosion of the underlying metal 

(Pelikán 1966).
Guide for Materials Selection and Design for Metals Used in Contact with Copper-Treated Wood

7

Using simple kinetic models of the corrosion rate dependence of metals on pH and on inhibitor efficiency, Zelinka 

and Stone developed the following relation to describe the 

dependence of corrosion on the pH and tannin concentration

 

where c is the concentration of tannins (mg L–1), , ,

and m are fitting parameters, and m > 0 (Zelinka and Stone 

2011b). From this equation, and from corrosion data measured in extracts of pine (low pH, low tannins) white oak 

(low pH, high tannins), American elm (high pH, low tannins), and black locust (high pH, high tannins) they developed an isocorrosion map (Fig. 7). While the numbers are 

higher than would be expected in solid wood, the same general trends are expected to apply in solid wood.

How Does the Corrosion of 

Fasteners Affect the Strength of 

the Connection? 

Up until this point, we have talked about corrosion rates in 

units of depth of metal loss per unit of time. However, what 

is ultimately important for metal fasteners used in construction is how this corrosion affects the strength of the connection. Recently, Zelinka and Rammer (2012) have used yield 

theory to examine how corrosion damage reduces the joint 

capacity. The yield theory selects the minimum of several 

failure modes that depend upon the dowel (nail) diameter 

and depth of penetration, the dowel-bearing stress of the 

wood members, the bending yield stress of the dowel, 

and the thickness of the wood members. For a given joint 

geometry, wood species and fastener bending yield stress, 

the equations depend only on the fastener diameter, which is 

Table 2. Summary of published corrosion rates (in μm y-1) in treated wood. The table 

represents a wide variety of test methodologies. Comparisons should only be made within 

a single row. 

Plain steel 

Hot dip 

galvanized 

steel Stainless steel Aluminum 

17 years, 27 °C (80 °F), 100% RH (Baker 

1992; Zelinka and Rammer 2009) 

9|CCA I 

6|CCA II 

<1|CCA I 

<1|CCA II 

3|CCA I 

4|CCA II 

1 year, 27 °C (80 °F), 100% RH (Zelinka 

and Rammer 2009) 

34|ACQ 61|ACQ 1|ACQ 22|ACQ 

1 year, 27 °C (80 °F), 100% RH (Zelinka 

and others 2010) 

9.4|CCA 

16.8|ACQ 

12.5|mCQ 

11.1|CA-B 

1.9|DDAC 

0.7|Untreated 

16.1|CCA 

32.5|ACQ 

19.4|mCQ 

28.9|CA-B 

5.5|DDAC 

4.4|Untreated 

 

1 year, 27 °C (80 °F), 

“moisture saturated air” (Kear and others 

2009) 

62|CCA 

176|ACQ-B 

84|CA-B 

26|CCA 

113|ACQ-B 

87|CA-B 

≤1|CCA 

≤1|ACQ-B 

≤1|CA-B 

1 year, 27 °C (80 °F), 90% RH (Kear and 

others 2009) 

4|CCA 

45|ACQ-B 

14|CA-B 

5|CCA 

26|ACQ-B 

16|CA-B 

≤1|CCA 

≤1|ACQ-B 

≤1|CA-B 

1 year, 27 °C (80 °F), 75% RH (Kear and 

others 2009) 

1|CCA 

3|ACQ-B 

2|CA-B 

1|CCA 

2|ACQ-B 

2|CA-B 

<1|CCA 

<1|ACQ-B 

<1|CA-B 

AWPA E12 (Anon. n.d.) 4|CuN-W 

1|CuN-O 

124|ACQ-D 

27|CCA-C 

11|CuN-W 

2|CuN-O 

23|ACQ-D 

10|CCA-C 

(‒1)|CuN-W 

2|CuN-O 

185|ACQ-D 

7|CCA-C 

AWPA E12 (Freeman and McIntyre 2008) 140| mCA 

107|CA 

23|mCA 

51|CA 

18|mCA 

(‒3)|CA 

AWPA E12 (Freeman and McIntyre 2008) 66|mCA 

180|CA 

41|mCQ 

196|ACQ-D 

41|CCA-C 

69|mCA 

76|CA 

41|mCQ 

81|ACQ-D 

53|CCA-C 

3|mCA 

0|CA 

0|mCQ 

3|ACQ-D 

3|CCA-C 

AWPA E12 (Freeman and McIntyre 2008) 89|mCQ 

307|ACQ-D 

76|CCA-C 

25|mCQ 

28|ACQ-D 

20|CCA-C 

10|mCQ 

10|ACQ-D 

5|CCA-C 

(2)
General Technical Report FPL–GTR–227

8

a function of the corrosion rate. The reduction of capacity in 

time is a straightforward calculation based upon the amount 

of the original diameter that remains.

These calculations assume that corrosion occurs uniformly 

across the length of the fastener, and that at failure, the 

wood moisture content is greater than 19%. The first assumption was necessary as the yield theory equations assume a constant fastener diameter; however, the maximum 

corrosion depth gives a conservative estimate. The second 

assumption was necessary as the dowel-bearing strength 

is independent of moisture content above 19% (Rammer 

2001). This is likely a valid assumption if fastener corrosion 

is occurring (see Fig. 5). 

Figures 8 and 9 show how these equations can be used to 

calculate the reduction in lateral capacity of an 8d (3.4-mm 

diameter) galvanized nail. This is a common nail size for 

decking applications where the expected side member thickness is greater than 21 mm and the resulting failure mode 

is Mode IV. For Mode IV failures, the yield strength is inversely related to the square of the diameter, which results 

in the lateral capacity decreasing rapidly with time as corrosion rate increases (Fig. 8). Figure 8 includes corrosion rates 

measured for galvanized steel embedded in untreated wood 

(5 μm y–1), and a hypothetical copper treatment with a corrosion rate of 60 μm y–1 exposed to 100% relative humidity 

(Zelinka and Rammer 2009). If an arbitrary failure criterion 

were applied (for instance, 50% of the original capacity), 

then a “time to failure” t(fail) can be calculated by 

 

where do is the original diameter of the fastener and R is 

the corrosion rate. Figure 9 graphically shows how changes 

in the corrosion rate, which may arise from fluctuations in 

moisture content or different treatment chemicals, affect this 

time to failure. It is important to note that measured corrosion rates in wood are on the steepest part of this curve. 

Therefore, even small changes in the wood moisture content 

have can have potentially large effects in the service life of 

fasteners embedded in wood.

How Can I Design To Minimize 

Corrosion in Treated Wood?

Metal fasteners are an essential part of wood construction 

and their use in preservative-treated wood cannot be avoided. Therefore, it is important to design and utilize metals in 

wood so that they will exhibit the least amount of corrosion. 

Here we discuss three design considerations that will help 

prolong the service life of metals in wood: proper moisture 

management, understanding non-metallic coatings and barriers, and avoiding mixed metals in construction.

Moisture Management

Proper moisture management is the most important thing 

one can do to reduce corrosion of metals in treated wood. If 

Figure 6. Iron-tannate precipitating in a solution with the 

same pH and tannin concentration as white oak. See 

Zelinka and Stone (2011b) for more information.

Figure 7. Isocorrosion map showing the interplay 

between tannins (abscissa) and pH (ordinate). Contours represent combinations of tannins and pH that 

result in the same corrosion rate. From Zelinka and 

Stone (2011b).
Guide for Materials Selection and Design for Metals Used in Contact with Copper-Treated Wood

9

wood is kept dry, both the wood and the fasteners can last 

for centuries (Clausen and Glass 2012). In most cases, preservative-treated wood is specified because the wood will be 

exposed in an outdoor environment where it will be exposed 

to rain and will get wet. However, sound design principles 

can maximize the drainage of rainwater and minimize the 

amount of moisture that is absorbed by the wood.

Clausen and Glass (2012) recently published a design guide 

for minimizing wood decay in residential construction by 

keeping the wood dry. Pertinent strategies that also apply to 

exterior structures and covered timber bridges involve 

(1) keeping rainwater from seeping in through the end grain 

and (2) designing roofs and overhangs so they do not drain 

onto lower structures.

End Grain

Moisture transport in the longitudinal direction (along the 

grain) is more than 10 times faster than in the radial or tangential directions. Therefore, if the end grain of the wood 

member is allowed to come into contact with liquid water, 

the entire member will absorb significant amounts of moisture. It is important to design the structure so that the end 

grain is not exposed to water. This frequently happens at 

joints between two members if the connection is improperly 

designed or installed and the joint traps water. Vertical members (e.g., posts) are especially prone to water uptake along 

the end grain. For these members, impermeable coatings or 

end caps could be used to reduce or prevent water uptake 

through the end grain.

Roof

For outdoor wooden structures with a roof, such as covered 

bridges, proper roof design and detailing can shield much of 

the structure from water, and keep the wood moisture content low. The larger the overhangs of the roof are, the less 

likely it is that drainage from the roof will strike the walls 

below it (Fig. 10).

Coated Metals

Paints and other nonmetallic coatings are frequently used to 

protect metals from corrosion by isolating the metal from 

the corrosive environment. The cost of coatings used to 

prevent corrosion is estimated at US$100 billion, which is 

36% of the total cost of corrosion in the United States, and 

1.1% GDP of the entire United States (Tator 2003). Whereas 

many different formulations of organic coatings are available, the goal of nearly all coatings is to isolate the metal 

from the environment.

Coatings fail when the corrosive environment can reach the 

metal substrate. This can happen if the coating is mechanically damaged during installation (Fig. 11). Zelinka and 

others (2009) observed that screws with a nonmetallic coating had a much worse corrosion performance after they had 

been driven into the wood or driven through a joist hanger 

into the wood and attributed this decrease in performance to 

damage in the coating caused by inserting the fastener into 

wood. Extreme care should be taken if using coated metals 

in construction with wood so that the coating does not get 

damaged before or during installation. 

Mixed Metals

Special design consideration is needed if two different metals are used in contact with each other. Galvanic 

corrosion happens when three conditions are satisfied: 

(1) two dissimilar metals (2) are placed in electrical contact 

(3) in the presence of an electrolyte. If any of the three 

Figure 8. Reduction in capacity of an 8d galvanized decking nail exhibiting a Mode IV failure (wood bearing failure 

with two plastic hinges) for two different corrosion rates. 

From Zelinka and Rammer 2012.

Figure 9. Illustration of how the "time to failure", in this 

case arbitrarily set to 50% of the original strength of the 

joint, changes with corrosion rate for the 8d galvanized 

decking nail shown in Figure 8.
General Technical Report FPL–GTR–227

10

conditions are not met (e.g., metals are not in electrical 

contact, metals are not in an electrolyte), galvanic corrosion 

cannot occur. When the conditions for galvanic corrosion 

are met, the more active metal (called the anode) will corrode more rapidly than it would otherwise corrode, and the 

more noble metal (called the cathode) will corrode more 

slowly than it would otherwise corrode. Whether a metal 

is active or noble to another metal depends upon the 

thermodynamics of the oxidation reactions in that 

environment.

Galvanic corrosion is a design concern in wood when a joist 

hanger or sign is attached to wood with a fastener. If the fastener is a different metal than the sheet metal, the conditions 

for galvanic corrosion exist: wood acts as the electrolyte and 

they are in electrical contact between the head of the fastener and the sheet metal.

It is important to point out a couple of common misunderstandings of galvanic corrosion at this point. For instance, 

commonly it is assumed that only the anode (“sacrificial anode”) corrodes in a galvanic couple. This is not true, as both 

metals corrode, but the cathode may corrode slowly enough 

that it does not fail in a normal service life. The second 

common misperception is that there is a single “galvanic 

series” that one can use to tell if a given metal will be active 

in a given environment. While galvanic series have been 

tabulated for seawater and other electrolytes (Matsukawa 

and others 2011), the positions of metals can change dramatically depending on the environment (e.g., treated wood).

An example of galvanic corrosion with wood was observed 

by the Wisconsin Department of Transportation (WisDOT) 

(Wilson 2004). In this case, aluminum signs were attached 

to sign posts made of treated wood with galvanized lag 

screws. The aluminum signs exhibited excessive corrosion 

around the lag screw, causing the sign to fall off in some 

cases. In this case, aluminum was acting as the anode, the 

galvanized lag screw, the cathode, and wood the electrolyte. 

As it would be difficult to change the sign material, and aluminum lag screws do not exist, it is impossible from a design perspective to change one of the metals to avoid corrosion. A better design solution would be to electrically isolate 

the aluminum sign from the galvanized lag screw (Fig. 12).

Figure 10. Illustration of the importance of roof overhangs 

for protecting wood from biodeterioration and corrosion. 

The right side of the beam is protected by the large roof 

overhang, whereas the left side is exposed to rain.

Figure 11. Corrosion underneath a coating failure. This lamp post was in service for less than 

5 years before corrosion was visible at defects 

in the coating.

Figure12. Strategies to mitigate galvanic corrosion. A nonconductive washer between the head of the lag screw and 

the sign should eliminate electrical contact between the 

bolt and the sign (Better). If there is a tight clearance between the hole and the bolt, it might be necessary to coat 

the edge of the holes to prevent electrical contact (Best).
Guide for Materials Selection and Design for Metals Used in Contact with Copper-Treated Wood

11

References

Anon 2007a. AWPA E-12: Standard method of determining 

corrosion of metal in contact with treated wood. Birmingham, AL: American Wood Preservers’ Association.

Anon 2007b. AWPA P5: Standard for waterborne preservatives. Birmingham, AL: American Wood Preservers’ Association. 

Anon 2007c. AWPA U1-06: Use category system. Birmingham, AL: American Wood Preservers’ Association.

Anon 2008. Preservative treated wood. Simpson Strong-Tie 

Technical Bulletin No. T-PTWOOD08-R. Pleasanton, CA: 

Simpson Strong Tie.

Anon. n.d. Copper Naphthenate Corrosivity Data. Retrieved 

from http://www.anthonyforest.com/pdfs/cunap_corrosivity.

pdf on April 1, 2013: El Dorado, AR: Anthony Forest Products. 

Baker, A.J. 1980. Corrosion of metal in wood products. Durability of building materials and components. ASTM STP 

691. West Conshohocken, PA: American Society for Testing 

and Materials. 981–993.

Baker, A.J. 1988. Corrosion of metals in preservative-treated 

wood. In: Hamel, M., ed. Wood protection techniques and 

the use of treated wood in construction. Madison, WI: Forest Products Society. 99–101.

Baker, A.J. 1992. Corrosion of nails in CCA- and ACAtreated wood in two environments. Forest Products Journal 

42(9): 39–41.

Balban, M.; Uçar, G. 2003. Estimation of volatile acids 

in wood and bark. Holz als Roh- und Werkstoff. 61(6): 

465–468.

Bootle, K.R. 1983. Corrosion aspects of wood use. In: Bootle, K.R., ed. Wood in Australia. Types, properties and uses. 

Sydney: McGraw-Hill Book Company. 62–67.

Clark, I.T.; Green, J. 1968. Production of phenols by 

cooking kraft lignin in alkaline solutions. Tappi Journal. 

51(1): 44–48.

Clausen, Carol A.; Glass, Samuel V. 2012. Build green: 

wood can last for centuries. General Technical Report FPL–

GTR–215. Madison, WI: U.S. Department of Agriculture, 

Forest Service, Forest Products Laboratory. 24 p.

Dennis, J.K.; Zou, C.; Short, N.R. 1995. Corrosion behaviour of zinc and zinc alloy coated steel in preservative 

treated timber. Transactions of the Institute of Metal Finishing. 75(3): 96–101.

Freeman, M.A.; McIntyre, C.R. 2008. A comprehensive 

review of copper-based wood preservatives with a focus on 

new micronized or dispersed copper systems. Forest Products Journal. 58(11): 6–27.

Hazlewood, P.E.; Singh, P.M.; Hsieh, J.S. 2006. Role of 

wood extractives in black liquor corrosiveness. Corrosion. 

62(10): 911–917.

Kear, G.; Wu, H.-Z.; Jones, M.S. 2009. Weight loss studies of fastener materials corrosion in contact with timbers 

treated with copper azole and alkaline copper quaternary 

compounds. Corrosion Science. 51(2): 252–262.

Knotkova-Cermakova, D.; Vlckova, J. 1971. Corrosive 

effect of plastics, rubber and wood on metals in confined 

spaces. British Corrosion Journal. 6(1): 17–22.

Lebow, S. 2004. Alternatives to Chromated Copper Arsenate for Residential Construction. Res. Pap. FPL–RP–618. 

USDA Forest Service, Forest Products Laboratory, Madison, 

WI.

Lebow, S. 2010. Wood Preservation. In: Wood handbook—

Wood as an engineering material. Chapter 15. Madison, 

WI: U.S. Department of Agriculture, Forest Service, Forest 

Products Laboratory: 15-1–15-28.

Legault, R.A.; Pearson, V.P. 1978. Kinetics of the atmospheric corrosion of galvanized steel. In: Coburn, S.K., ed. 

Atmospheric factors affecting the corrosion of engineering 

metals, ASTM STP 646. West Conshohocken, PA: American 

Society for Testing and Materials. 83–96.

Legault, R.A.; Preban, A.G. 1975. Kinetics of the atmospheric corrosion of low-alloy steels in an industrial environment. Corrosion. 31(4): 117–122.

Mabrour, J.; Akssira, M.; Azzi, M.; Zertoubi, M.; Saib, N.; 

Messaoudi, A.; Albizane, A.; Tahiri, S. 2004. Effect of vegetal tannin on anodic copper dissolution in chloride solutions. 

Corrosion Science. 46(8): 1833–1847.

Matamala, G.; Smeltzer, W.; Droguett, G. 2000. Comparison 

of steel anticorrosive protection formulated with natural tannins extracted from acacia and from pine bark. Corrosion 

Science. 42(8): 1351–1362.

Matsukawa, Y.; Chuta, H.; Miyashita, M.; Yoshikawa, M.; 

Miyata, Y.; Asakura, S. 2011. Galvanic series of metals 

conventionally used in tap water with and without flow 

and its comparison to that in seawater. Corrosion. 67(12): 

125004–7.

Mittendorf, S. 2009. Letter to the editor: Hardware corrosion from PT lumber: looking for answers. Journal of Light 

Construction. 27(10): 13–13.

Nasrazadani, S. 1997. The application of infrared spectroscopy to a study of phosphoric and tannic acids interactions with magnetite (Fe3O4), goethite ([alpha]-FEOOH) 

and lepidocrocite ([gamma]-FeOOH). Corrosion Science. 

39(10–11): 1845–1859.

Niemelä, K. 1989. GLC-MS Studies on pine kraft black 

liquors Part V. identification of catechol compounds. Holzforschung. 43(2): 99–103.
General Technical Report FPL–GTR–227

12

Packman, D.F. 1960. The acidity of wood. Holzforschung. 

14(6): 178–183.

Pelikán, J.B. 1966. Conservation of iron with tannin. Studies 

in Conservation. 11(3): 109–115.

Radojcic, I.; Berkovic, K.; Kovac, S.; Vorkapic-Furac, J. 

2008. Natural honey and black radish juice as tin corrosion 

inhibitors. Corrosion Science. 50: 1498–1504.

Rahim, A.A.; Rocca, E.; Steinmetz, J.; Kassim, M.J. 2008. 

Inhibitive action of mangrove tannins and phosphoric acid 

on pre-rusted steel via electrochemical methods. Corrosion 

Science. 50(6): 1546–1550.

Rammer, D.R. 2001. Effect of moisture content on nail bearing strength. Res. Pap. FPL-RP-591. Madison, WI: U.S. 

Department of Agriculture, Forest Service, Forest Products 

Laboratory. 22 p.

Rammer, D.R.; Zelinka, S.L. 2008. Analytical determination 

of the surface area of a threaded fastener. ASTM Journal of 

Testing and Evaluation. 36(1): 80–88.

Rammer, D.R.; Zelinka, S.L. 2010. Optical method for measuring the surface area of a threaded fastener. Experimental 

Techniques. 34(4): 36–39.

Short, N.R.; Dennis, J.K. 1997. Corrosion resistance of zincalloy coated steel in construction industry environments. 

Transactions of the Institute of Metal Finishing. 75(2): 

47–52.

Simons, P.J.; Levy, J.F.; Spiro, M. 1998. Electrical migration 

of exogenous mineral ions through green sapwood of Pinus 

sylvestris L. (Scots pine). Wood Science and Technology. 

32(6): 411–419.

Tator, K.B. 2003. Introduction to coatings and linings. In: 

Cramer, S.D. and Covino, B.S., eds. Materials Park, OH: 

ASM International. 814–816.

Wilson, J. 2004. Aluminum sign corrosion investigation. 

Final Report #WI-06-04 WisDOT Highway Research Study 

#WI-04-02. Madison, WI: Wisconsin Department of Transportation. 

Zelinka, S.L. 2007. Uncertainties in corrosion rate measurements of fasteners exposed to treated wood at 100% relative 

humidity. ASTM Journal of Testing and Evaluation. 35(1): 

106–109.

Zelinka, S.L.; Derome, D.; Glass, S.V. 2011. Combining A 

Hygrothermal And Corrosion Model To Predict Corrosion 

Of Metal Fasteners Embedded In Wood. Building and Environment. 46(10): 2060–2068.

Zelinka, S.L.; Ortiz-Candelaria, L.; Stone, D.S.; Rammer, 

D.R. 2009. Electrochemical impedance spectroscopy (EIS) 

as a tool for measuring corrosion of polymer-coated fasteners used in treated wood. Forest Products Journal. 59(1/2): 

77–82. 

Zelinka, S.L.; Rammer, D.R. 2009. Corrosion rates of fasteners in treated wood exposed to 100% relative humidity. 

ASCE Journal of Materials in Civil Engineering. 21(12): 

758–763.

Zelinka, S.L.; Rammer, D.R. 2011. Synthesis of published 

and unpublished corrosion data from long term tests of fasteners embedded in wood: calculation of corrosion rates and 

the effect of corrosion on lateral joint strength. In CORROSION 2011. Houston, TX: NACE International.

Zelinka, S.L.; Rammer, D.R. 2012. Modeling the effect of 

nail corrosion on the lateral strength of joints Forest Products Journal 62(3):160–166.

Zelinka, S.L.; Rammer, D.R.; Stone, D.S. 2008. Electrochemical corrosion testing of fasteners in wood extract. Corrosion Science. 50(5): 1251–1257.

Zelinka, S.L.; Rammer, D.R.; Stone, D.S.; Gilbertson, J.T. 

2007. Direct current testing to measure corrosiveness of 

wood preservatives. Corrosion Science. 49(3): 1673–1685.

Zelinka, S.L.; Sichel, R.J.; Stone, D.S. 2010. Exposure testing of fasteners in preservative treated wood: gravimetric 

corrosion rates and corrosion product analyses. Corrosion 

Science. 52(12): 3943–3948.

Zelinka, S.L.; Stone, D.S. 2011a. Corrosion of metals in 

wood: Comparing the results of a rapid test method with 

long-term exposure tests across six wood treatments. Corrosion Science. 53(5): 1708–1714.

Zelinka, S.L.; Stone, D.S. 2011b. The effect of tannins and 

pH on the corrosion of steel in wood extracts. Materials and 

Corrosion. 62(8): 739–744.

Zhang, X.G. 2003. Corrosion of zinc and zinc alloys. In: 

Cramer, S.D.;Covino, B.S., eds. ASM Handbook Volume 

13B, Corrosion: Materials. Materials Park, OH: ASM International. 402-417.

Zhang, X.G.; Hwang, J.; Wu, W.K. 1998. Corrosion testing 

of steel and zinc. In: Proceedings of the 4th International 

Conference on Zinc and Zinc Alloy Coated Steel Sheet 

(GALVATECH ‘98). Chiba, Japan.