The cuticulin envelope

(1) It is a selectively permeable barrier. During breakdown of the old cuticle, it allows the “activating factor” f for the molting gel to move out and the products of cuticular hydrolysis to enter, yet it is impermeable to the enzymes in the molting fluid. It is permeable to waxes (as these are deposited only after the cuticulin layer has formed) and, in some insects, it permits the entry of water.
(2) It is inelastic and, therefore, serves as a limiter of growth.
(3) It provides the base on which the wax monolayer sits. The nature of the cuticulin envelope will therefore determine whether the wax molecules are oriented with their polar or nonpolar groups facing outward and, therefore, the surface properties of the cuticle.
(4) It plays a role in determining the surface pattern of the cuticle.
(5) It is resistant to abrasion and helps prevent infection.
(6) It is involved in production of physical colors