Review of Wood Drying Research in Brazil: 1984–2004 Ivaldo P. Jankowsky and Maria ˆngela Gonc ¸alves Luiz Department of Forest Sciences, ESALQ, University of Sa ˜ o Paulo, Piracicaba, Sa ˜ o Paulo, Brazil In Brazil, research on wood drying has been more focused on applied aspects than on fundamentals ones, and results have been published almost exclusively in Brazilian journals. The study of lum- ber deformation under aggressive drying conditions resulted in methods to group species and to define kiln schedules. Relationship between moisture content and electrical resistivity was used to improve quality control of dried lumber as well automatic control of the kiln drying process. Conventional kiln drying is the most common method for industrial drying, but seasoning and solar dry- ing were also studied. The biggest research effort was directed to improve the drying of eucalypt lumber. Keywords Wood drying; Drying research; Lumber drying INTRODUCTION The main sources of wood in Brazil are the dense tropical forest or Amazonian forest, covering 412 million hectares concentrated in the northern region, and the fast growing forests, over 4.7 million hectares in the south- eastern and southern regions. Tropical forest is characterized by hundreds of different hardwood tree species, growing at an estimated rate of 3.0 m 3 =ha.year, and only 60% (around 245 million hectares) of the forest can be considered as suitable for technical and economical exploration. Planted forests concentrate a few species, mainly from genus Eucalyptus (63%) and Pinus (35%), growing at rates from 25.0 to 100.0m 3 =ha.year and are managed as an agricultural plantation. Wood-based products from tropical species are almost exclusively plywood and lumber, although round wood from Eucalyptus planted forests are mainly directed to energy and pulp industries, and from Pinus forests, to pro- duce plywood and lumber. Lumber production in 2002 was around 14.4 million m 3 of tropical species and 7.9 million m 3 of pine. [1] From the produced saw wood, 10.0% of tropical and 26.0% of pine was exported as lumber or manufactured products. Concern about maintenance of Amazonian forest resources, which includes tree species, is making the requirements for sustainable forest management more severe. Management issues should be considered to receive legal approval from environmental agencies to explore tropical forest, and one aspect of great importance is to harvest a large number of different tree species, keeping biodiversity and regeneration potential as close as possible to original forest. One consequence is the increase of unknown tropical species to industrial supply and, at same time, the increased production of planted Eucalyptus grandis lumber as a replacement for tropical hardwood. Due the importance of drying to add quality and value to wood-based products, industries have quickly adjusted drying technology to this changing lumber supply, with reflection on the search for technical information and research. Brazil has a few universities with experts and facilities to carry out studies on wood drying, and in the last two decades the research effort was directed to applied aspects, with emphasis to improve the drying of lumber. The principal results of wood drying research in Brazil are now presented, first grouped by the fundamental aspect analyzed and then followed by the type of lumber. WATER-WOOD RELATIONSHIP Research about water-wood relationship includes moisture movement, wood permeability, electrical resist- ance, and equilibrium moisture content prediction. Most published papers discuss the physical property knowledge as a tool to improve drying process and quality of dried lumber. Moisture gradient during convective drying of timber, in the hygroscopic range, causes internal stress related to the consequent shrinkage gradient. Those stresses are nonuni- form across board thickness and can be the origin of degra- dation as surface checks, internal checks, and case hardening. The study of moisture gradient and drying stress in Pinus caribaea var. hondurensis wood, using a ‘‘slicing technique,’’ corroborates the high permeability of conifer- ous species and demonstrate that stress patterns of drying Correspondence: Ivaldo P. Jankowsky, Department of Forest Sciences, ESALQ, USP, P.O. Box 9, 13418-900, Piracicaba-SP, Brazil; E-mail: jpjankow@eslaq.usp.br Drying Technology, 24: 447–455, 2006 Copyright # 2006 Taylor & Francis Group, LLC ISSN: 0737-3937 print/1532-2300 online DOI: 10.1080/07373930600611893 447