Dust and debris can enter the crack. When the glass tries to flex, the debris acts like a wedge, preventing the crack from "healing" and pushing the glass apart.
If you must drive the vehicle before getting it repaired, follow these rules to minimize vibration and stress: how to stop windshield crack from spreading
While these methods are (except for professional resin injection), they can buy you time until a repair or replacement is possible. Dust and debris can enter the crack
Apply a small piece of clear tape over the damage. This won't stop the crack from growing, but it keeps dirt and moisture out of the fracture, which is critical if you want a professional repair to be successful later. Apply a small piece of clear tape over the damage
A small chip in your windshield can turn into a spiderweb of cracks overnight if left untreated. Because your windshield is a structural component made of laminated glass (two layers of glass with a plastic interlayer), even minor impacts create stress points that are highly susceptible to expansion.
: Apply a strip of clear packing tape over the damage. This prevents dirt and moisture from entering the crack, which can make it impossible to repair later.