Is moisture really the most important influencing factor on the mechanical properties of claw horn? Modulus of elasticity and dry-matter content in flat and contracted claws.

The modulus of elasticity (E) and dry matter content (DMC) of horn samples from two types of claw deformity (contracted and flat claws) were determined according to EN-ISO 527 and ASTM D 638-03. The overall E values for all segments combined were 168 +/- 154 MPa (mean +/- SD, n = 79) and 248 +/- 196 (n = 90) for contracted and flat claws, respectively. These values were approximately 60% and 40% less than the E value of sound claw material. The high correlation between E and DMC, as previously found for sound claw horn material was not present in horn obtained from these types of pathologically altered claws.