Duplex board

When evaluating Duplex Board, the most critical factor is the GSM (Grams per Square Meter), typically ranging from 230gsm to 450gsm. You must distinguish between Grey Back (more economical, used for standard packaging) and White Back (used for premium food or pharmaceutical packaging). Ensure the bursting strength and stiffness (Taber Stiffness) meet your specific packaging structural requirements to prevent box deformation during stacking.

Check the coating consistency and surface smoothness (PPS). A high-quality Duplex Board should have a multi-layer clay coating to ensure ink absorption is uniform and colors remain vibrant. Request a brightness level report (usually 78%-84% for coated white top) to ensure it aligns with your brand's visual standards.

For food-grade packaging, the board must comply with FDA (US) or ISEGA (EU) certifications. For general exports, ensure the supplier provides FSC (Forest Stewardship Council) certification to prove sustainable sourcing, and SGS/RoHS reports to confirm the absence of heavy metals and harmful chemicals, which is vital for customs clearance in strictly regulated markets.

Request the Cobb Value test results, which measure the water absorption rate of the paper surface. A lower Cobb value indicates better moisture resistance, which is essential if the goods are shipped via sea freight or stored in humid environments. Additionally, verify the ply bond strength to ensure the layers do not delaminate during the die-cutting or folding process.

The biggest risk is moisture damage and edge crushing. You should mandate that the supplier uses plastic film wrapping (stretch wrap) on all pallets and installs reinforced paper corner protectors. Ensure the container is inspected for leaks and that desiccant bags are placed inside to prevent 'container rain' during long transit periods.

Paper prices fluctuate based on pulp market indices. It is wise to negotiate a formula-based pricing for long-term contracts. For MOQs, while large mills prefer 20ft container loads (approx. 18-20 tons), you can negotiate smaller trial runs by sourcing from verified gold suppliers on Made-in-China.com who maintain local stock.

Always use Letter of Credit (L/C) for large volume orders to mitigate financial risk. For initial deposits, utilize secured payment services provided by reputable platforms like Made-in-China.com to ensure your funds are protected until the Third-Party Pre-shipment Inspection (PSI) is completed and the Bill of Lading is issued.

Include a clause in your contract specifying that quality claims must be filed within 30 days of arrival. Retain original samples from the production batch and the mill test certificate (MTC). If a defect is found, provide photographic evidence and a third-party laboratory report to facilitate a refund or credit on the next order.