Enzyme Mixture Improves Creosote Treatment of Kiln-Dried Rocky Mountain Douglas-Fir

In pilot tests, introducing an enzyme solution into round sections of Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca) markedly improved the creosote treatment of this hard-to-treat species. The treating solution contained diluted commercial pectinase and ammonium oxalate adjusted to a pH of 3.5. The solution was applied by pressure impregnation to the green poles before kiln-drying and the subsequent preservative treatment. The enzyme pretreatment increased the depth of creosote penetration to full sapwood (l-1/2 in.) uptake as compared to partial uptake in controls, increased the total creosote retentions from 4.50 to 9.41 pounds per cubic foot, and in the Lowry process produced an essentially “dry” surface, free from post-treatment bleeding. The better penetration and retention is attributed to partial erosion or complete disintegration of the bordered pit torus as revealed by scanning electron micrographs. The paper has a generous number of photographs and photomicrographs that illustrate the events observed. The cost of the treating solution used in these tests was estimated to be approximately 15 cents per foot. No improvement in heartwood treatability was noted.

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