Ambient humidity directly affects the flexibility of cellulose bonds and is a primary determinant of the Fiber Cracking phenomenon. When board moisture decreases due to improper storage, the fibers become brittle, and their tensile stress threshold drops significantly. In such conditions, even with standard Creasing operations, the fibers physically rupture during folding instead of displacing and bending. This structural failure results in visible Cracking across the surface layers, exposing the white inner core of the paperboard and compromising the package's aesthetics.

To manage this challenge, consultants recommend maintaining relative humidity in production and storage areas between 45% and 55% to preserve the fibers' elastic properties. Additionally, using humidifiers near the Die Cut machine can minimize the risk of breakage during dry seasons. Periodically inspecting the material before printing and using control samples for 180-degree fold tests are practical steps to ensure fiber integrity. These proactive measures prevent the rejection of entire production batches and ensure a high-quality finished product for the end user.