Research on final moisture content as a factor of wood drying quality

In lumber drying there is a strong need for the right evaluation of the whole process, in a way to simplify the determination of drying quality class as much as possible with respect to the industrial needs. The evaluation of the final MC is part of these wishes. According to the future obligatory standard, a research of final moisture content was made, for the purpose of the drying quality class determination. The materials used were oakwood dimension parts (270 by 58 by 27 mm) for parquet production being from 1st to 3rd grades, and they were dried in a conventional kiln dryer in two processes. The final moisture content as estimated by moisture meters and determined using the oven-dry method on each of the 30 samples per kiln load. After the moisture meter reading each sample was sawn into 18 pieces for the oven drying method, to determine the range of moisture readings and to compare it to the future drying quality standard. The oven-dry method showed a difference between the moisture meter readlngs compared to the oven-dry method results, and the difference in the moisture content between the inner and outer layers of the oakwood dimension parts. An estimation of the moisture content (measured with a moisture meter on 1/3 of the thickness) did not fulfil the expectations, if compared with oven-dry results. The differences in the moisture content between the readings at 1/2 and 1/6 of thickness are classified as the highest possible class, which shows the right conditioning treatment. It can be concluded that the real moisture content in wood is very different compared to the values measured by moisture meters, that it has great dissipation, and that the proposed methods of standardised measurements and drying quality class determination have to be seriously reconsidered. The proposed ways are easier for the industrial praxis but of less precision.