Recovery in viscid line fibers.

The development of a reliable procedure for removing the viscous coating of viscid silk has allowed the accurate characterization of the tensile behavior of clean flagelliform silk (i.e., silk of the flagelliform gland without the viscous coating synthetised in the aggregate gland). For comparison, tensile tests on native viscid silk (with the viscous coating) fibers were also performed. It was found that viscid silk, either native or clean, has an elastomeric behavior when kept wet, either by immersion in water (clean fibers) or by the effect of the viscid coating (native fibers). When tested in dry environments (35% RH, relative humidity, for clean fibers and 10% RH for native fibers), their mechanical behavior was no longer elastomeric, with it being more similar to other silk fibers. Furthermore, it was noticed that flagelliform silk fibers show a ground state to which they can return independent of the previous loading history.