Improving the quality of bog oak boards using microwave drying chambers

Abstract

The stocks of bog oak taken from the bottom of reservoirs are increasingly used to preserve growing valuable species of wood, primarily oak. English oak (Quercus pedunculata Ehrh.) is a hard-drying species. Drying modes of oak boards have been well developed for both convection and microwave drying. The interest in bog oak, rose out from water bodies, sharply increased, but it turned out to be impossible to dry it using known methods other than microwave drying. Cracking defects are 70% at a thickness of 30 mm and 100% at a cross section of 60 mm. The article analyzes the results of bog oak drying in laboratory-type microwave chambers. The distance between magnetrons was 0.5 m, and a length of boards was 1.2 m. A semicommercial plant with a loading volume of 2 m3 and total power of 30 kW was used. Total drying time for boards with a total loading volume of 0.2 m3 was from 3 to 5 days. Cracking defects reduced to 20% for a thickness of 30 mm and to 32% for a thickness of 60 mm (with additional treatment by 40% carbamide solution). Board warping was not noticed.