Penetrability and Strength of White Spruce After Ponding

Thirty-six bolts obtained from four small white spruce trees (Picea glauca [Moench] Voss) were ponded in a natural lake in Petawawa, Ontario, in an investigation to establish the optimal ponding period for satisfactory creosote impregnation under pressure, causing minimal loss in strength properties. The results showed that a ponding period of 5 weeks was sufficient to ensure full sapwood penetration on the air-dried bolts in an 8-hour Lowry process. Retentions were increased by 155 percent over the controls, stored indoors. Static bending tests carried out on the sapwood of bolts ponded for 9 weeks showed slight reductions in strength properties: 4.5, 3.8, 1.8 percent in fiber stress at proportional limit, modulus of rupture and modulus of elasticity, respectively. Susceptibility to fungal decay, pH value, and color of wood were not affected by ponding. Heavy compression wood interfered with, penetration of creosote into ponded wood.

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