Drying Ochroma pyramidale from Costa Rican plantations using kiln, solar and air drying: time, moisture content, color and drying defects

Abstract

Balsa (Ochroma pyramidale) holds significant market importance due to its rapid growth and the low density (<0.2 g/cm³) of its wood. Extensive areas of balsa have been established in many tropical regions; however, knowledge about drying wood from this species remains limited. This study evaluated kiln drying (KD), solar drying (SD), and air drying (AD)—in terms of drying time, wood color, and the presence of defects such as warp, splits, and cracks—of 6-cm-thick lumber from 1.7- and 4.5-year-old balsa plantations in Costa Rica. Drying time was shortest for KD, while SD required an intermediate duration between KD and AD. Balsa wood dried using KD exhibited statistically significant differences in all three color parameters, with the highest overall color change. Conversely, wood dried using SD and AD displayed similar values for the three color parameters, with minimal color change. Boards exhibited varying levels of warping (crook, bow, cup, and twist), splits, and checking before drying. SD resulted in similar defect levels (incidence, magnitude, and quality index) to AD. However, KD caused the greatest changes in wood quality and the highest defect incidence. While KD allowed for drying balsa wood with fewer defects in the shortest time, the highest wood quality was achieved with SD and AD, albeit requiring longer drying durations.