Considerations on Drying Frozen Spruce Wood and Effects upon Its Properties Mihaela Campean, Mihai Ispas, and Mihaela Porojan Faculty of Wood Industry, ‘‘Transilvania’’ University of Brasov, Romania The aricle presents the results of a research performed in order to establish whether drying lumber from frozen state (in winter) has repercussions upon its properties, compared to drying under the same conditions lumber parts originating from the same log and position within the log section but that were not frozen prior to dry- ing. To this purpose, spruce (Picea abies L.) lumber specimens, 35 mm and 55 mm thick, cut from the same log, half frozen at 30  C and half unfrozen, were dried under the same conditions in a climate chamber. Some mechanical properties (hardness, bend- ing strength, and modulus elasticity in static bending), as well as workability (expressed by means of the absorbed power and specific resistance to cutting during milling), were determined The results revealed slight differences between the frozen and the unfrozen sam- ples both during the drying process and afterwards. It was noticed that a significant amount of water was removed from wood during the very beginning of the heating phase (thawing). With regards to wood properties after drying, a slight lowering of the mechanical properties and better workability could be established for the initially frozen samples. Keywords Bending strength; Frozen wood; Hardness; Modulus of elasticity in static bending; Spruce; Water removal; Workability INTRODUCTION During winter, it is typical for lumber stored in an open yard to freeze. According to Cividini, [1] only free water freezes in wood if the temperature does not drop below 30  C. Considering this situation, the authors aimed to establish whether the freezing affects the physical, mechan- ical, and technological properties of the dried wood. There- fore, research has been initiated to determine some mechanical properties (hardness, bending strength, and elasticity modulus) and some technological properties (workability expressed by means of the absorbed power and the specific resistance to cutting during milling) of spruce (Picea abies L.) wood samples originating from the same log, half of them being frozen in green state at  30  C first and then dried, while the other half was dried from the unfrozen green state, by using the same drying conditions. The effect of prefreezing upon the hygroscopicity and dimensional stability of different wood species has been studied before by numerous authors. [2–7] The results obtained recommend prefreezing as a successful pretreat- ment method for the drying of both hardwoods and soft- woods from temperate and tropical regions, with a view to reducing shrinkage, collapse, and warp simultaneously with increasing the drying rate. [3,5,7] Correspondence: Mihaela Campean, Faculty of Wood Indus- try, ‘‘Transilvania’’ University of Brasov, B-dul Eroilor nr. 29, 500136 Brasov, Romania; E-mail: campean@unitbv.ro FIG. 1. Cutting scheme for obtaining wood specimens to be dried: D1, D2, D3, D4, D5, D6—unfrozen samples; I1, I2, I3, I4, I5, I6—frozen samples. Drying Technology, 26: 596–601, 2008 Copyright # 2008 Taylor & Francis Group, LLC ISSN: 0737-3937 print/1532-2300 online DOI: 10.1080/07373930801946411 596