It is important to select inorganic copper compounds as a main active ingredient for research and development of an effective preservative such as CCA for impregnation process in soil contact use. Because copper is a reliable component as a wood preservative with longlasting effectiveness in soil contact use.
However corrosivity and instability of copper solution against iron should be improved in case of practical use as a wood preservative for impregnation.
Basic experimental results on this formulation study showed that the best copper raw material for non-corrosive copper solution was copper compounds free from corrosive anion such as copper carbonate and the best solvent was mixture of ethanolamine and alkyldiamine (5:1 weight by weight EA+AA).
The fixation study results on Sugi sapwood (Cryptorneria japonica) treated with the copper-amine preservatives showed that the copper-EA+AA combination (CEA) gave more than 80% copper fixation rate same as CCA No.1 and the copper-alkyldiamine combination gave 20-30% copper fixation rate same as 2% solution of copper sulfata. The results of decay and termite registance tests according to JIS A 9201-1991 and JWPAS No.12-1992 showed that CEA satisfied the requirements at 0.3% copper concentration against termite and white rot fungus Coriolus uersicolar.
However CEA did not satisfied the requirement against brown rot fungus Tyromyces palstris (TP) even at 0.7% copper concentration. The main reason why CEA did not pass the JIS test agaist TP might be due to its copper-tolerance nature rather than due to leach ing out of copper because Sugi specimens treated with CEA showed more than 80% copper fixation rate after leaching procedure.

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