I.  Laboratory Efficacy Studies

I-1.  Grace, J. K., Yamamoto, R. T., Laks, P. E. 1993.  Evaluation of the termite resistance of wood pressure treated with copper naphthenate.  For. Prod. J., Vol. 43, Number 11-12, pp.72-76.  CA: 120:238241

Southern pine wafers pressure-treated with copper naphthenate in American Wood-Preservers' Association P9 Type A oil or in toluene were evaluated for resistance to attack by the Formosan subterranean termite Coptotermes formosanus (Isoptera: Rhinotermitidae).  Wood samples were pressure treated to target copper retentions of 0.040, 0.075, 0.095, or 0.150 pcf, conditioned to simulate field exposure, and exposed to termites in 4-wk no choice and two-choice lab tests.  Copper retentions were assayed by x-ray fluorescence after treatment, after leaching, and again after exposure to the termites.  An approx. 20 % loss of copper after weathering and termite exposure was noted in samples treated to target retentions of 0.095 and 0.150 pcf Cu.  With or without a heavy oil carrier, copper naphthenate showed some toxicity to termites and deterred termites from feeding on the treated wood.  At the highest target retentions of 0.095 and 0.150 pcf Cu, southern pine wt. losses from termite feeding did not exceed 4 % in no-choice tests or 1 % in two-choice tests.  Similar results were observed in no-choice tests with Douglas-fir blocks treated with copper naphthenate in oil or toluene.  Field data are needed, but these results indicate that copper naphthenate pressure treatments are of value in protecting wood from attack by the Formosan subterranean termite.

I-2.  Pohleven, F., Petric, M. 1995.   The biological properties of copper and zinc carboxylates in wood preservation. Conf. Coord. Chem., 15th(Current Trends in Coordination Chemistry), 379-82.  CA: 124:48281

The fungicidal efficacy of 33 copper and zinc carboxylates and the insecticidal and termiticidal activity of copper octanoate and naphthenate as well as zinc and iron naphthenate were studied.  The strongest fungicidal and insecticidal activity was shown by copper and zinc naphthenates and copper octanoate.  Copper octanoate is sol. in white spirit and also in aqueous ammonia solutions.  One day after treatment, leaching of carboxylates from wood was very low.  The flammability of treated wood was not influenced by the tested substances.

I-3.  Kamdem, D. P., Gruber, K., Freeman, M. 1995.  Laboratory evaluation of the decay resistance of red oak (Quercus rubra) pressure treated with copper naphthenate.  For. Prod. J., Volume Date 1995, 45(9), 74-6.  CA: 124:59531

Northern red oak cubes pressure-treated with Cu naphthenate in toluene solvent were evaluated for decay resistance after exposure to brown and white rot fungi.  Sapwood cubes were pressure-treated to a target elemental Cu retention ranging from 0.112 to 4 kg/m3.  Cu retentions of treated samples were determined by atomic absorption spectrometry and by wt. gain.  Treated samples were conditioned to an equilibrium moisture content of 12% and then exposed to fungi for 16 wk.  At 1.28 kg/m3, elemental Cu retention, wt. loss of northern red oak cubes exposed to brown rot Gloeophyllum trabeum or white rot Pleurotus ostreatus or Trametes versicolor fungi was ≤3%.  A higher elemental Cu retention of 1.6 kg/m3 was needed to protect red oak against the Cu-tolerant brown rot Poria placenta.

I-4.  Kamdem, D. P.; Fair, R.; Freeman, M. 1996. Efficacy of water-borne emulsion of copper naphthenate as preservative for northern red oak (Quercus rubra) and soft maple (Acer rubrum).  Holz als Roh- und Werkstoff, Vol. 54, No. 3, pp. 183-187.

Northern red oak (Quercus rubra) and red maple (Acer rubrum) cubes pressure treated with a water borne formulation of copper naphthenate were evaluated for resistance to attack by brown fungi Gloeophyllum trabeum and Poria placenta [Oligoporus placenta], white rot fungi Trametes versicolor [Coriolus versicolor], Irpex lacteus and Pleurotus ostreatus, and soft rot fungi Chaetomium globosum and Phialophora sp. Wood samples measuring 19 by 19 mm were pressure treated to target copper retentions of 12.48 kg/m3 (0.78 pcf), 9.77 kg/m3 (0.61 pcf), 5.6 kg/m3 (0.35 pcf), 4.5 kg/m3 (0.30 pcf), 2.56 kg/m3 (0.16 pcf),1.2 kg/m3 (0.075 pcf), 0.48 kg/m3 (0.03 pcf). Data from laboratory soil block tests indicate that at 2.0 plus or minus 0.5 kg/m3 (0.13 pcf) copper retention from water borne copper naphthenate, the protection is similar to that from 1.6 kg/m3 (0.10 pcf) elemental copper from oil borne copper naphthenate or 7.2 kg/m3 (0.45 pcf) total oxide from CCA-C. Higher copper levels (3.0 plus or minus 0.2 kg/m3) are needed to protect against copper tolerant brown rot fungus Oligoporus placenta. Results from an American Wood Preserver's Association standard leaching test indicate that water borne copper naphthenate treated samples retained 80 to 90% of the copper initially absorbed. The amount of leached copper increases with the pH of the leaching solution.

I-5.  Morrell, J. J. 1992.  Copper tolerant fungi: a brief review on their effects and distribution.  Proc. - Annu. Meet. Am. Wood-Preserv. Assoc., Volume Date 1991, Volume 87, pp. 265-70.  CA: 121:4544

Copper compounds represent an important class of fungicides. Recent efforts to incorporate copper naphthenate for wood treatment into the commodity standards of the American Wood Preserver's Assoc. have raised questions about the importance of copper-detoxifying brown rot fungi.  Copper-tolerant fungi associated with wood are surveyed and their mechanisms of tolerance are discussed.  The relative importance of these fungi in the performance of copper-containing wood preservatives is delineated.

I-6.  Minich, A. and Goll, M. 1948.  The Technical Aspects of Copper Naphthenate as a Wood Preserving Chemical.  Proc. - Annu. Meet. Am. Wood-Preserv. Assoc., Volume Date 1948, Volume 44, pp. 265-70.

Technical aspects of copper naphthenate are discussed, including physical properties such as vapor pressure and solubility in water and organic solvents, efficacy against wood decay fungi, and suggestions for treating wood are given.  Analytical methods and proposed specifications for AWPA Standards are also given.  Copper naphthenate is a chemical compound of uniform performance and a highly effective and permanent wood preservative, it is easy to apply and is safe to handle.

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