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What Is a Pulp Tray?

Paul Scott
Paul Scott

A pulp tray is an effective packaging element produced from paper pulp. Molded paper pulp products are made by reducing waste paper to a pulp in a process that includes the addition of various property-enhancing agents. A porous mold is then immersed in the pulp where water is drawn through it by a powerful vacuum. This caused the paper fibers in the pulp to adhere to the outside of the mold, effectively taking on its form. The molded paper part is then removed from the mold, dried, and packaged for distribution.

The ubiquitous pulp tray is one of the most common packaging materials in general use and is encountered in applications as diverse as shock absorbing inserts in high-end electronics packaging to drinks trays in fast-food outlets. The products can be produced to absorb or contain fluids, and may be made in a wide range of shapes, colors, and textures. The pulp tray is also an excellent green product example, as most are made using recycled waste paper in a process that is geared to optimizing water usage during production. The process used to manufacture molded paper pulp items is also fairly simple, leading to outstanding costing in comparison to other packaging solutions.

Pulp trays are made from recycled paper such as newsprint.
Pulp trays are made from recycled paper such as newsprint.

The pulp tray production process begins with the collection of waste paper, including corrugated packaging and newsprint. The paper is turned to a pulp by adding water and exposing it to a reduction process, during which stabilizing and binding agents such as soluble wax and aluminum sulphate are added. Once the pulp is ready, a mold of the desired product is immersed in it. The molds are porous and connected to a powerful vacuum source and a waste water reticulation system.

Once immersed, the vacuum is activated, which draws water through the mold across its entire surface. This action causes the paper fibers suspended in the pulp to cling to the outside of the mold as the water passes through. The water that passes through the mold is then collected and circulated back to the pulp reduction process for re-use. When the layer of adhering fiber reaches the desired thickness, the mold is removed from the pulp. The pulp tray, which accurately mirrors the mold surface, may now be removed using a transfer mold and put into an electric element or thermic fluid drying device where they are slowly dried in readiness for distribution.

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    • Pulp trays are made from recycled paper such as newsprint.
      By: Orlando Bellini
      Pulp trays are made from recycled paper such as newsprint.