This paper examines how the moisture conditioning method affects the electrical conductance of wood. A widely used dataset was acquired by Stamm in 1929 who used a method of conditioning where water-saturated wood specimens were partially dried, sealed and left for a period of time for moisture to be redistributed before the electrical conductance was measured. However, more recent measurements combined conditioning above saturated salt solutions and pressure plate/pressure membrane techniques to obtain equilibrium moisture contents at constant relative humidity levels in the full moisture range. In this paper, the electrical conductance as a function of moisture content was compared for these two conditioning methods. When the specimens were conditioned to constant relative humidity levels, the data obeyed a percolation model better than when the conditioning procedure by Stamm was used. This was attributed to that Stamm’s method gives moisture gradients through the specimen because of sorption hysteresis effects, even though the wood is conditioned to a steady-state moisture content. Equilibration to constant relative humidity levels thus provided more well-defined moisture states and that the data followed a percolation model indicates that the mechanism of electrical conduction in wood does not change, even at high moisture contents.

中文翻译：

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由不均匀水分分布引起的木材电气测量中的伪影

本文研究了水分调节方法如何影响木材的电导率。Stamm 在 1929 年获得了一个广泛使用的数据集，他使用了一种调节方法，即在测量电导之前，将水饱和的木材样品部分干燥、密封并放置一段时间以使水分重新分布。然而，最近的测量结合了饱和盐溶液上方的调节和压力板/压力膜技术，以在整个水分范围内获得恒定相对湿度水平下的平衡水分含量。在本文中，比较了这两种调节方法的电导率与水分含量的关系。当样品被调节到恒定的相对湿度水平时，与使用 Stamm 的调节程序相比，数据更符合渗透模型。这归因于 Stamm 的方法由于吸附滞后效应而导致整个样品的水分梯度，即使木材被调节到稳态水分含量。因此，与恒定相对湿度水平的平衡提供了更明确的水分状态，并且遵循渗透模型的数据表明，即使在高水分含量下，木材中的导电机制也不会改变。