The variability of swelling and shrinkage of Vermillion wood (Ptrocarpus spp.) was studied. It was found that when the wood was steamed it swelled much more along the tangential direction than along the radial; consequently, the percentage of tangential shrinkage (yT, %) proved much less than that of radial shrinkage (yr, %) throughout the whole drying process until the MC reduced to 5% and lower. The value of the ratio of (100-yT)/(100-yT) might be used to predict whether or not dry checks would occur on the tangential surface during drying. This (100-Yt)/ (100-yr) Cor 0= a(100-yT)/(100-yr) 3 ratio has been given the term dry check potential by the author. The bigger the ratio, the smaller the potential. The steaming treatment could reduce the potential to such a degree that the dry check on the tangential surface would never occur. By using the steaming preheating treatment, verr million lumber of 10 to 35 millimeters thickness was successfully dried in superheated vapour. The lumber dried was of good quality.