Copper naphthenate - protecting America’s infrastructure for over 100 years and its potential for expanded use in Canada and Europe

Figures & data

Table 1. Alternative oil-type preservatives.

Tradename	Manufacturer	Active ingredient(s)	Formulants, solvents
QNAP8	Nisus Corporation	Copper hydroxide, 11.5%	Naphthenic acid (60%) Petroleum-based carrier oil
SleeperProtect	Koppers	Copper hydroxide, 4.6%; Ethoxylated didecylmethylamine propanoate salt, 6%, Cyproconazole, 0.15%,	Crude Tall acids (89-90%)
Tanasote	Arch Timber Protection (Lonza)	Copper hydroxide, 4.62%; DDA Carbonate, 0.75%; Penflufen, 0.0375%	Petroleum-based carrier oil (90-95%) Propane -1,2-diol Methanol

Figure 1. Performance of naphthenic acid vs. other carboxylic acids (Marsh et al. 1944, Table 6). (a) 9-day soil burial results (b) 7-day Metarrhizium sp. exposure results.

Figure 2. Performance of oil-borne preservatives in USDA FPL-RN-01 Fence Post Study.

Table 2. Average service life of creosote, pentachlorophenol and CuN treated fence posts exposed during USDA FPL-RN-01 study in Mississippi, USA.

Preservative	Predicted service life (Davidson 1977)	Predicted service life* (Freeman et al. 2005)
CuN in 5% petroleum	42	65.2
Pentachlorophenol in 5% petroleum (Wyoming residual)	36	55.5
Creosote, straight run low residue (“SRLR”)	37	45.7
Untreated controls	3.6	2.4

* Estimated 60th percentile.

Table 3. Preservative retention and percentage of pass/fail posts evaluated after 54 years (Freeman et al. 2005, reporting on 2003 inspection results).

Preservative	Solution retention, kg/m^3 (pcf)	Posts failed as of 2003 inspection*	Posts passing** at 2003 inspection
CuN, 0.5% (Cu as metal) in petroleum oil	96 (6.0) 0.48 (0.03) as Cu	48%	52%
Pentachlorophenol, 5% in petroleum oil	96 (6.0) 4.8 (0.30) as Penta	60%	40%
Creosote, SRLR	94.4 (5.9)	88%	12%
Untreated controls	0	100%	0%

* Assumes posts missing at inspection had failed.

** Percentage of original 25 replicate posts installed.

Table 4. Known life spans of CuN stakes in the USDA-FPL-02 Studies (Woodward et al. 2011, Table 7).

Cu concentration in CuN/Stoddard solvent, %	Solution Retention, kg/m^3 (pcf)	CuN Retention, as Cu, kg/m^3 (pcf)	Estimated Life, years
0.11	164.8 (10.3)	0.19 (0.012)	15.9
0.29	163.2 (10.2)	0.46 (0.029)	21.8
0.57	169.6 (10.6)	0.98 (0.061)	27.1
0.86	153.6 (9.6)	1.31 (0.082)	29.6
Untreated controls	0.0	0.0	1.8

Table 5. CuN in Canadian pole stub studies (Stirling et al. 2017).

Species	Treatment	Process	Retention, kg/m^3 (pcf) of active	Mean service life, years
Red pine	Untreated	–	–	3.8
Red pine	Pentachlorophenol	Full cell	8.0 (0.5)	> 49.0
Jack pine	Untreated	–	–	5.5
Jack pine	CuN (1% Cu)	Rueping	1.3 (0.08)	> 65.0

Figure 3. Performance of biodiesel-amended copper naphthenate treatments in field stake study (from Presley et al. 2019). (a) OSU forest test site (b) OSU field test site.

Marsh, P., Greathouse, G., Bollenbacher, K. and Butler, M. (1944) Copper soaps as rot-proofing agents for fabrics. Industrial and Engineering Chemistry, 36(2), 176–181.

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Davidson, H. L. (1977) Comparison of wood preservatives in Mississippi Post Study (1977 Progress Report). FPL-RN-01. USDA Forest Service, Forest Products Laboratory. Madison, WI. 17 p.

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Freeman, M. H., Crawford, D., Lebow, P. and Brient, J. A. (2005): A comparison of wood preservatives in posts in southern Mississippi: results from A half-Decade of testing. Proceedings of the American Wood-Preservation Association, 101, 136–143.

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Woodward, B. M., Hatfield, C. A. and Lebow, S. T. (2011) Com­parison of wood preservatives in Stake Tests: 2011 Progress Report. Research Note FPL-RN-02. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 120 p.

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Stirling, R., Ingram, J., Wong, D. and Morris, P. (2017) Field Testing in Canada XXVI: Posts and Poles. Submitted to the Canadian Wood Preservation Association, Proceedings of the 38th Annual Meeting, Toronto, Ontario. October 25-26, 2017.

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