400 GSM+ Mill Board, Color : Grey Sheets

• ​Composition: Made from 100% post-consumer waste (Recycled Corrugated Containers - OCC, newsprint, and office waste). It is essentially multiple layers of paper pulp bonded under extreme heat and pressure.
• ​Appearance: Typically matte grey or brown. The surface can be "calendered" (pressed with hot rollers) to create a smooth finish for high-end printing or left "natural" for industrial use.
• ​Rigidity: Its defining feature. Unlike flexible paper, millboard is stiff and non-bending, designed to provide structural integrity to the products it protects.
• ​GSM Range: 400 to 2500\text{ g/m}^2.

                 ​Thickness: 0.5 mm} to 4.0 mm

​Moisture Content: Strictly 8% to 12%. If it's too high, the boards warp; if too low, they become brittle and crack during die-cutting.

​pH Level: Usually neutral (7.0) to prevent "yellowing" or chemical reactions with the glues used in bookbinding.