Selecting the correct substrate is the foundation of quality. For heavy-duty shopping bags, prioritize Virgin Kraft Paper due to its long fibers and superior tensile strength. If you are targeting eco-conscious markets, Recycled Kraft Paper is an excellent choice, though it may have a lower bursting strength. For luxury retail, Art Paper (Coated Paper) is preferred as it allows for high-fidelity offset printing and various finishes like UV coating or foil stamping. Always verify the GSM (Grams per Square Meter); typically, 100-120 GSM is standard for small bags, while 150-180 GSM is required for premium or large-format carriers.