The Effect of Steaming Time and Temperature on the Longitudinal Permeability of Black Walnut

Longitudinal permeability to water of black walnut sapwood and heartwood specimen plugs was determined before and after steam treatments for 1, 2, 3, and 4 h and two temperatures (100 C and 115 C). Steaming heartwood specimens at 115 C gave three times greater increase in longitudinal permeability than steaming at 100 C. Also, steaming heartwood specimens at 115 C for 4 h gave the greatest and most significant increase (560%) in longitudinal permeability of all other steaming times (which averaged about 90% increase). However, steam treatment caused very little change in longitudinal permeability of sapwood. Steaming at 100 C for 4 h reduced the ratio of longitudinal permeability of sapwood to heartwood from 24,000 to approximately 10,000. Steaming at 115 C for 4 h reduced this ratio to about 4,000.