Physical Deterioration 

of Preservative Treated 

Poles and Pilings 

Exposed to Salt Water 

Grant T. Kirker

Jessie Glaeser

Stan T. Lebow

Frederick Green III

Carol A. Clausen

United States

Department of

Agriculture

Forest Service

Forest

Products

Laboratory

General

Technical

Report

FPL–GTR–203
September 2011

Kirker, Grant T.; Glaeser, Jessie; Lebow, Stan T.; Green III, Frederick; 

Clausen, Carol A. 2011. Physical Deterioration of Preservative Treated 

Poles and Pilings Exposed to Salt Water. General Technical Report FPLGTR-203. Madison, WI: U.S. Department of Agriculture, Forest Service, 

Forest Products Laboratory. 5 p.

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Abstract

This report details the results of laboratory analyses of 

wooden pilings sent to the USDA Forest Products Laboratory in March 2011. These samples were removed from 

coastal wooden posts, poles, piles, and deck boards. A total 

of 22 samples, consisting of either core borings or surface 

fiber samples, were removed from four installations along 

the South Carolina coast. Methods focusing on the physical, 

chemical, and biological properties of the wood determined 

that the 22 specimen samples consisting of core borings and 

surface fiber samples were physically deteriorated by salt 

accumulation and not biological deterioration. This report 

presents the findings of these analyses and discusses the 

cause of the documented damage. 

Keywords: defibration, salt damage, salt kill, pilings, dock 

fungus, non-biological damage, tracheid separation.

Acknowledgments

Thank you to Jim Healey of Cox Industries for the sampling 

and data collection in Charleston, South Carolina; Tom 

Kuster, FPL Forest Products Technologist, for conducting 

SEM/EDAX analyses; and Dan Foster, FPL Chemist, for 

conducting the IC analysis. 

Significance of Cover Photo: Salt damage or “fuzzy wood” 

can be mistaken for biological deterioration, although it 

actually represents physical deterioration. This image of a 

deck piling has extensive salt damage from seawater exposure. The seawater is wicked through the piling by capillary forces, splashed up by wave action, and as the water 

evaporates, the residual salt is deposited in the fibers near 

the top of the pole. This is commonly seen in wood exposed 

to saline conditions and is largely considered cosmetic damage. As illustrated in this picture, the pilings do not have 

to be submerged in saltwater for damage to occur; these 

pilings were located directly adjacent to a wharf in Charleston, South Carolina, and were frequently inundated with 

seawater. (Photo provided by Jim Healey, Cox Industries, 

Orangeburg, South Carolina).

Contents

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

Materials and Methods........................................................ 1

Results and Discussion ....................................................... 2

 Physical Properties of the Wood ..................................... 2

 Microscopic Examination ............................................... 3

 SEM ................................................................................ 3

 ICP–AES Results............................................................ 3

References........................................................................... 4

Appendix—Summary Information for 22 Samples............ 5
Physical Deterioration of Preservative 

Treated Poles and Pilings Exposed 

to Salt Water

Grant T. Kirker, Research Forest Products Technologist1

Jessie Glaeser, Research Plant Pathologist2

Stan T. Lebow, Research Forest Products Technologist1

Frederick Green III, Research Microbiologist1

Carol A. Clausen, Supervisory Research Microbiologist1

1U.S. Department of Agriculture Forest Service, Forest Products Laboratory, Madison, Wisconsin

2U.S. Department of Agriculture Forest Service, Northern Research Station, Madison, Wisconsin

Introduction

Wood has been used in marine settings for hundreds of 

years. Treated pilings offer protection from biological deterioration from marine organisms and extend the service 

life of the product. Wood in marine contact is also subject 

to uptake and accumulation of salt, primarily sodium and 

potassium chloride, from the seawater that is splashed onto 

the pilings by wave action and salt spray, and physically 

wicked up through the pole by capillary forces. The evaporation of the seawater from the surface of the submerged 

piling leaves residual salt crystals that are reported to precipitate and disrupt the middle lamella and separate the 

tracheid fibers (Johnson and others 1992). The result is an 

orange-brown, fuzzy appearance that is normally considered 

cosmetic and does not affect the structural integrity of the 

piling. Salt damage can be found in almost every instance in 

which wood comes in frequent contact with brine, including alkaline salt storage areas (Parameswaran 1981) and 

archeological sites (Blanchette 2002). Salt damage is sometimes confused with brown-rot decay, but the bright orange 

color of the affected area is the only similarity between the 

two. Brown-rot decay fungi are equipped with cellulytic 

enzymes that degrade the cellulose fibers in the wood, leaving the brown cubical remnants (lignin) behind (Kirk and 

Highley 1973). Whereas marine fungi exist (Leightley and 

Eaton1979), brown-rot fungi are terrestrial and not equipped 

to survive in marine environments (Jones and others 2000). 

Comparatively, white-rot fungi are capable of degrading 

both lignin and cellulose in wood and cause a bleached 

white, spongy appearance because of the presence of residual cellulose fibers (Kirk and Highley 1973). White-rot 

fungi are also not compatible with or frequently encountered 

in marine environments. Additionally, soft-rot fungi occur 

in environments with high moisture and require an external 

nutrient source to degrade the wood (Worrall 1991). This 

type of decay is not as aggressive as white or brown rots 

and also is uncommon in marine areas. The images and data 

collected and compiled for this technical report are based on 

samples and pile cores received at the Forest Products Laboratory (FPL) for analysis. Our results reinforce the conclusion that the discolored wood is due almost entirely to salt 

precipitation that results in physical disruption and damage 

to the wood fibers and not fungal decay. These results are 

consistent with the results reported by Johnson and others 

(1992). 

Materials and Methods

 A total of 16 pile cores and six surface fiber samples were 

obtained by Cox Industries (Orangeburg, South Carolina) 

and submitted to FPL for analysis. Samples were collected 

from posts, poles, piles, and deck boards. The samples were 

collected in and around the port of Charleston in Charleston, South Carolina. Most of the samples were collected in 

the Litchfield Beach community, which is located approximately 500 yards from the ocean. Other sample locations 

included Isle of Palms Marina, Wild Dunes Marina, and a 

more southern location (Blufton) located near Hilton Head, 

South Carolina. A single sample of wood fiber was also 

received from Shem Creek, located in Mount Pleasant, 

50 yards from a tidal creek. 

Samples were divided and subjected to five types of analyses: pH, light microscopy, scanning electron microscopy, 

EDAX (energy dispersive X-ray analysis, and ICP–AES 

(inductively coupled plasma spectroscopy—atomic emission spectroscopy). Visible examinations and pH determinations were conducted on all samples. Fifteen increment 

borings were sectioned and examined for the presence of 

fungi using light microscopy. A minimum of three sections 

was made of each specimen in order to examine the wood 

cells in radial and transverse (cross sectional) views. Each 

specimen was stained with lacto-phenol/cotton blue—a stain 

that preferentially dyes fungal hyphae bright blue—and 

examined at 450×, 600×, and 1000×. When fungal hyphae 

were observed in the wood or on the surface of the specimen under low magnification (100×), additional sections or 

surface tape mounts were made of the wood in that area.For 
General Technical Report FPL–GTR–302

2

scanning electron microscopy (SEM) of the marine pilings, 

fibers or 5- by 7-mm pieces of wood were placed on sticky 

silver tape on aluminum mounts and coated with gold using a Denton Desk-1 sputter coater (Denton Vacuum, LLC, 

Moorestown, New Jersey). Samples were examined and 

photographed with a LEO EVO 40 SEM (Carl Zeiss NTS, 

Peabody, Massachusetts) at 15 kV.

For EDAX analysis, piling fibers were pelletized in a Parr 

press (Parr Instrument Company, Moline, Illinois); or 

if samples were solid, 5- by 5-mm pieces of wood were 

mounted on carbon stubs with sticky carbon tape. Uncoated 

specimens were viewed in the LEO EVO 40 at a variable 

pressure of 40 Pascals at 1.0nA’s and 20kV. EDAX analysis 

was performed using an IXRF 550i system with a 50-mm 

SSD detector (IXRF Systems, Inc. Houston, Texas). Spectra 

were collected for 100 seconds.

ICP–AES analysis was conducted on all samples to determine the preservative retention and sodium content. Sample 

preparation and instrument calibration was conducted in 

accordance with AWPA standard A21 (AWPA 2010). This 

method details the procedure for digesting a wood sample 

and analyzing the resulting solution for preservative components. The AWPA standard density value for southern pine 

(512 kg/m3) was used to calculate preservative concentration on a weight/volume basis (AWPA 2010).

Results and Discussion

Physical Properties of the Wood

Upon receipt of the wood samples, they were screened for 

basic properties. Visual observations were made and pH 

of the samples was obtained on extracts of each sample in 

deionized water using a Corning pH/ion meter and probe 

(Corning Incorporated, Corning, New York). PH values of 

the individual samples are presented in the sample summary 

(Fig. 1). Typically, brown-rot decay produces oxalic acid 

in order to facilitate the decay process, and production of 

oxalic acid will decrease wood pH to around 2 (Green and 

others 1991). The pH of these samples was consistent with 

the normal pH range of wood (i.e., 4.5–6.5). 

Microscopic Examination

No decay fungi were observed in any of the specimens. 

Certain specimens contained brown-pigmented fungi within 

the tracheids or ray cells of the wood. These fungi are most 

likely Aureobasidium pullulans, the “black yeast fungus,” 

or common mold fungi (technically “dematiaceous hyphomycetes”) that cause dark stains in wood when exposed 

to moisture. The common mold fungus Cladosporium 

cladosporioides was found on the surface of many of the 

increment borings. This fungus is probably present in the 

wood and then grew on the surface of the increment boring while it was confined within the high humidity of the 

plastic collection tube. One sample, Litch P6, contained 

non-pigmented fungal hyphae within the wood cells that did 

not contain clamp connections typically present in decay 

fungi. For example, the brown-rot decay fungus Fibroporia 

radiculosa (=Antrodia radiculosa) is characterized by large, 

frequent clamp connections; there was no indication that 

this fungus was present in any of the samples. In fact, there 

was no microscopic evidence of brown-rot wood decay at 

the cellular level.

SEM

SEM micrographs were generated for a subset of the 

samples. The advantages of SEM are that high-resolution 

images can be obtained at micrometer scale and this method 

allows us to observe changes to the wood structure as well 

as the presence of fungal hyphae. No indication of brown-, 

white-, or soft-rot fungi were found in any of the samples. 

Tracheid separation was apparent in marina samples 

(Fig. 2), and SEM micrographs did show cubical salt 

crystals throughout the marina sample (Fig. 3). Oxalic 

acid crystals are typically needle-like or tetrahedral (Green 

and others 1996).

ICP–AES Results

As expected when sampling a range of commodities treated 

for different use categories, the samples collected in this 

study exhibited a wide range of preservative retentions 

(Fig. 4). The observed retentions generally appear to be in 

accordance with expected values, although differences in 

assay zones and sample composition makes comparisons 

difficult. The relative proportions of chromium, copper, and 

arsenic within the samples in this study did not indicate any 

systematic depletion of either copper or arsenic. The proportions of chromium, copper, and arsenic in exposed CCAtreated wood can provide some indication of the extent of 

leaching because chromium is more leach-resistant than 

copper or arsenic (Lebow 1996). Sodium concentrations in 

all but one sample were over 1,000 ppm, and many samples 

contained over 10,000-ppm sodium. In contrast, naturally 

3

2

1

0

4

5

6

7

Log pH values

Litchfield Beach 

Isle of Palms Marina

Wild Dunes Marina

Shem Creek

Bluffton

Figure 1. Ranges of pH values found in submitted fuzzy 

wood and pile cores. 
Physical Deterioration of Preservative Treated Poles and Pilings Exposed to Salt Water

3

occurring sodium concentrations in Southern Pine wood 

have been reported to vary from 28 to 130 ppm (Choong 

and others 1974; Cutter and others 1980). The single sample 

with lower sodium levels (130 ppm) was removed from a 

pole approximately 135 meters from the water. It is noteworthy that this pole did not show any evidence of surface 

deterioration. It is also noteworthy that the five greatest 

sodium concentrations were associated with surface fiber 

samples (Fig. 5). These results confirmed the presence of sodium in the affected wood and corroborate the EDAX data 

implicating salt as the causative agent of the fuzzy wood. 

The poles and piles that were sampled were not of a uniform 

use class, but ICP–AES indicated retentions of CCA and 

ACQ were within the acceptable retention range based on 

their service age. Also, ICP–AES analysis found on average 

4× as much sodium (Na) in the fuzzy wood samples than 

was found in the core samples. These results confirmed the 

presence of sodium chloride (NaCl) and corroborate the 

EDAX data implicating salt as the causative agent of the 

fuzzy wood (Fig. 6). A full summary of all samples received 

and the results of the individual analyses is presented in 

the Appendix.

Figure 2. Image of salt-damaged pilings and corresponding sample showing tracheid separations and 

no fungal presence using SEM (175× magnification).

Figure 3. Image of salt damaged deckboards at Isle of 

Palms Marina (a) and salt crystals (white arrows) located in corresponding sample using Scanning Electron Microscopy (b, 450× magnification). 

0

70

60

50

40

30

20

10

Retention (kg/m3

)

Litchfield Beach 

Isle of Palms Marina

Wild Dunes Marina

Shem Creek

Bluffton

Figure 4. Retention of preservative in samples removed 

from poles, piles, posts, or decking.
General Technical Report FPL–GTR–302

4

References

AWPA. 2010. Book of standards. Birmingham, AL: 

American Wood Protection Association. 566 p.

Blanchette, R.A.; Held, B.W.; Farrell, R.L. 2002. Defibration of wood in the expedition huts of Antarctica: an unusual 

deterioration process in the polar environment. Polar 

Record. 38: 313–322.

Choong, I.; Chang, B.Y.; Kowalczuki, J. 1974. Mineral 

composition in loblolly pine wood after fertilization. LSU 

Wood Utilization Notes. No. 26. 5 p.

Cutter, B.E.; McGinnes, E.A.; McKown, D.H. 1980. Inorganic concentrations in selected woods and charcoals measured using NAA. Wood and Fiber Science. 12(2): 72–79. 

Green, F., III; Kuster, T.A.; Highley, T.L. 1996. Pectin degradation during colonization of wood by brown-rot fungi. 

Recent Research Developments in Plant Pathology 

1: 83–93.

Green, F., III; Larsen, M.J.; Winandy, J.E.; Highley, T.L. 

1991. Role of oxalic acid in incipient brown-rot decay. 

Material und Organismen. 26:191–213. 

Johnson, B.R.; Ibach, R.E.; Baker, A.J. 1992. Effect of 

salt water evaporation on tracheid separation from wood 

surfaces. Forest Products Journal. 42(7/8):57–59.

Jones, E.B.G. 2000. Marine fungi: some factors influencing 

biodiversity. Fungal Diversity. 4:53–73.

Kirk, T.K.; Highley, T.L. 1973. Quantitative changes in 

structural components of conifer woods during decay by 

white- and brown-rot fungi. Phytopath. 63: 1338–1342. 

Lebow, S.T. 1996. Leaching of wood preservative components and their mobility in the environment: summary of 

pertinent literature. Gen. Tech. Rep. FPL–GTR–93. Madison, WI: U.S. Department of Agriculture, Forest Service, 

Forest Products Laboratory. 36 p.

Leightley, L.E.; Eaton, R.A. 1979. Nia vibrissa—a marine 

white-rot fungus. Transactions of the British Mycological 

Society. 73(1): 35–40. 

Parameswaran, N. 1981. Micromorphology of spruce timber after long-term service in a potash store house. Holz als 

Roh- und Werkstoff. 39: 149–156. 

Worrall, J.J.; Anagnost, S.E.; Wang, C.J.K. 1991. Conditions 

for soft rot of wood. Canadian Journal of Microbiology. 

37: 869–874.

0

70,000

40,000

50,000

60,000

30,000

20,000

10,000

Sodium concentration (ppm)

Litchfield Beach 

Isle of Palms Marina

Wild Dunes Marina

Shem Creek

Bluffton

Figure 5. Sodium concentration in samples removed from 

poles, piles, posts, or decking. Ovals around symbols denote surface fiber samples.

8.0K

Cnts

6.0K

4.0K

2.0K

1 2 3 4 5 6

Fe Fe Fe

Mg

Si

Al

Ca

Ca

Cl

K

S

C

Ca

Na

O

Cl

Chlorine (Cl)

keV

S

Figure 6. Analysis using EDAX found an abundant amount 

of sodium and chlorine relative to the other elements (including carbon and oxygen) as evidence of NaCl. 
Physical Deterioration of Preservative Treated Poles and Pilings Exposed to Salt Water

5

Summary information for 22 samplesa

Retention in PCF 

(assumes 32 lb/ft3)

Additional 

analyses 

Sample name Location Treatment

DFWb

(yardsc) Type

Treat 

date 

Use 

class 

Target 

retention 

Weight

(g) NAd As O2 5 CrO3 CuO

Total 

preservative

retention pHe SEMf

Microscopicg

IOP 1 Isle of Palms Marina CCA 3 Core 1990 Land pile 0.8 0.5065 53.284 0.21 0.31 0.13 0.64 5.45 — X IOP 3 deck board Isle of Palms Marina ACQ-C 3 Fuzzy wood Unknown Above ground 0.8 0.4671 461.63 0.03 0.06 0.02 0.12 5.28 X — IOP 4 Isle of Palms Marina CCA 3 Core 1990 Land pile 0.8 0.4999 119.62 0.23 0.33 0.12 0.67 6.03 — X IOP 2 Jet Ski Isle of Palms Marina CCA 0 Fuzzy wood Unknown Marine pile 2.5 0.4559 180.02 1.14 1.44 1.25 3.83 5.3 X —Litch P1 Litchfield Beach CCA 50 Core 1978 Land pile 0.8 0.4799 123.3 0.07 0.09 0.02 0.18 5.15 — X Litch P2 Litchfield Beach CCA 20 Core 1978 Land pile 0.8 0.5778 88.89 0.15 0.2 0.08 0.43 4.89 — X Litch P3 Litchfield Beach CCA 75 Core 1978 Land pile 0.8 0.5137 19.376 0.25 0.38 0.15 0.78 5.66 — X 

Litch P4 Litchfield Beach CCA 50 Core 1978 Land pile 0.8 0.4768 178 0.14 0.22 0.05 0.42 5.29 — X Litch P5 Litchfield Beach CCA 20 Core 1978 Land pile 0.8 0.5504 55.408 0.16 0.26 0.09 0.51 5.12 — X

Litch P6 Litchfield Beach CCA 100 Core 1978 Land pile 0.8 0.4653 115.74 0.36 0.54 0.09 0.99 5.68 — X 

Litch P8 Litchfield Beach CCA 150 Core 1978 Land pile 0.8 0.4935 235.23 0.06 0.09 0.02 0.17 4.68 — X Litch P8 back Litchfield Beach CCA 150 Core 1978 Land pile 0.8 0.4819 177.6 0.11 0.13 0.06 0.3 4.96 — X 

Litch P9 Litchfield Beach CCA 150 Core 1978 Land pile 0.8 0.4747 1.234 0.27 0.41 0.17 0.84 5.83 — X Litchfield pile 6 Litchfield Beach CCA 100 Fuzzy wood 1978 Land pile 0.8 0.5838 526.23 1.54 0.89 1.12 3.54 5.73 — — Litchfield pile 7 Litchfield Beach CCA 100 Fuzzy wood 1978 Land pile 0.8 0.5365 341.46 0.54 0.75 0.7 1.99 4.72 X — SCEG #1 bag Blufton CCA 3 Fuzzy wood 2002 Land pile 0.6 0.4715 540.36 0.28 0.43 0.12 0.84 4.69 X — SCEG 1 Blufton CCA 3 Core 2002 Land pile 0.6 0.4862 179.5 0.14 0.2 0.07 0.41 4.75 — X SCEG 2 Blufton CCA 3 Core 2002 Land pile 0.6 0.4795 237.17 0.14 0.2 0.06 0.41 5.36 — X Shem Creek Shem Creek ACQ-C 3 Fuzzy wood Unknown Post (6 × 6) 0.6 0.4981 334.45 0 0 0.15 0.15 4.81 X —

WD 1 Wild Dunes Marina CCA 0 Core 2001 Marine pile 2.5 0.5164 36.456 0.58 0.94 0.32 1.84 6.44 — X WD 2 Wild Dunes Marina CCA 0 Core 2001 Marine pile 2.5 0.4768 226.04 0.57 0.76 0.24 1.56 5.48 — X WD 3 Wild Dunes Marina CCA 0 Core 2001 Marine pile 2.5 0.1101 3.689 0.62 1.6 0.34 2.56 6.18 X X aSamples were received at USDA FS FPL located in Madison, Wisconsin. bDistance from water. c1 yard = 0.9144 meters

dNot applicable. 

epH analyzed by Carol Clausen, Supervisory Research Microbiologist at FPL. fSEM analyzed by Tom Kuster, Microscopist at FPL. 

Appendix—Summary Information for 22 Samples

gAnalyzed by Jessie Glaeser, Research Plant Pathologist at NRS. 

a