Moulded pulp

Molded pulp, also named moulded pulp or molded fibre, is a packaging material, typically made from recycled paperboard and/or newsprint. It is used for protective packaging or for food service trays and beverage carriers. Other typical uses are end caps, trays, plates, bowls and clamshell containers.

For many applications, molded pulp is less expensive than expanded polystyrene (EPS), vacuumed formed PET and PVC, corrugation, and foams.

Molded pulp is often considered a sustainable packaging material, as defined by the Sustainable Packaging Coalition, since it is produced from recycled materials, and can be recycled again after its useful life-cycle.

Molded pulp products can be made waterproof with a spray or dip coating of wax.

Several types of molded pulp can be manufactured by several processes.

These products usually have wall thicknesses of 1/16" to 1/4" and are used primarily for support packaging applications. Thick-Wall is also commonly referred to as "Slush Molded." The surfaces are very rough on one side and moderately smooth on the opposite side. Product definition is moderate due to the use of relatively inexpensive single-pass molds and the use of mixed recovered paper and kraft paper slurries. Typical uses are for edge and edge protector, heavy item packaging, auto replacement parts, molded pulp pallet trays etc.

Transfer molded products are usually thin walled, 1/16" to 3/16", and are the most prevalent type in use today. The process uses vacuum forming and take-off or transfer molds, where the mold is an extremely fine wire mesh in the shape of the upper/exposed surface. The fibrous slurries are frequently made up of a high percentage or entirely of recycled newspaper, which produces a relatively smooth surface on one side and a fairly smooth surface on the opposite side with good accuracy and definition.

Prior to the molding process, the mesh is mated with a vacuum chamber that draws water through the mesh into the chamber, with the mesh mold suspended above a liquid return pool. The fibrous slurry is sprayed from below onto the mold, and the vacuum draws the slurry tightly against the mesh, filling all gaps and spaces. When airflow through the mesh has been sufficiently blocked, the excess slurry falls into the return pool for recycling, and the mold advances onward to the drying process, following by separation of the mesh mold from the dried fiber plating.

...
Wikipedia