Prior to shedding the former exoskeleton, the organism will have already formed a new exoskeleton beneath the old one, although in a softer form. Once the old one is shed, the new one will harden in 24 - 48 hours,depending on the species.

It is important to keep in mind that by the time of the initial onset of molting, a new cuticle that will be hardened or remineralized after the old exoskeleton is shed, has already been formed. After molting, the arthropod takes large quantities of water (for aquatic species) or air (for terrestrial species) into it's gut and expands its new cuticle to its maximum extent before the onset of hardening. It is at this time that the arthropod is in it's most vulnerable state and is easy prey for anything that might stumble across it, and thus typically retreats to a small hole or crevice for shelter (more common for aquatic species). In marine crustaceans, for instance, it usually only takes a couple of days before the new cuticle has become heavily enough calcified for it to return to it's normal mode of life. In terrestrial arthropods the process of exoskeleton hardening is much more rapid and is usually completed in less that a few hours, but can vary as a function of animal size and atmospheric conditions.