Janka hardness using nonstandard specimens

Janka hardness determined on 1.5- by 3.5-in. specimens (2x4s) was found to be equivalent to that determined using the 2- by 2-in. specimen specified in ASTM D 143. Data are presented on the relationship between Janka hardness and the strength of clear wood. Analysis of historical data determined using standard specimens indicated no difference between side hardness values determined on the radial face as opposed to the tangential. Analysis of historical data also indicated that the relationship between hardness modulus (HM) and Janka hardness (H) may be different for hardwood species than for softwood. Recommendations are given for ensuring that experimental procedures do not bias the results when testing non-standard specimens. The authors caution that if hardness (ASTM D 143) and hardness modulus (ASTM D 1037) are measured simultaneously for each ball penetration, the HM/H ratio may be different than that given in D 1037 because the two standards specify different rates of penetration.