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Cellulose molding is the process used to create recyclable packaging material. This material is created using only recycled newspaper and corrugated cardboard. Great everyday examples of containers made with molded pulp are the trays used to carry various beverages in fast food restaurants, ladle-type containers and food trays. The popularity of this type of container has increased considerably in the last 10 to 15 years, as consumers have begun to demand recyclable packaging.
There are four types of pulp molding products available to consumers: thick-walled, transfer, thermoformed, and processed fiber. All four methods require significant amounts of energy and pressure to mold the recycled fibers into the required shapes. It is important to note that although the finished product is made from recycled materials, a significant amount of water and energy is required to create the final product. The sheer need for resources has led some experts to question whether these products are really better for the environment.
Heavy wall pulp molding is used for packaging heavy items, molded pulp pallet trays, and auto parts. The product itself is quite rough on one side and slightly smoother on the other. The intended use of this type of cellulose molding is for heavy materials. Roughness is not the main concern, but relative strength. Many companies design thick-walled products to withstand significant pressure, and often evaluate different products to help people decide which one to use.
Transfer products have thinner walls and are created using a process very similar to papier-mâché sculptures. The process is the most widely used production method for cellulose molding materials. A mold is created using a very fine wire mesh in the reverse shape of the final product. Fibrous materials are sprayed onto the mould, completely covering it; as the material dries, the metal frame is separated from the product and reused. To see an example of a product made with this process, look at the beverage trays, coasters, egg trays, or fruit trays used in stores.
The most recent development in cellulose molding is thermoformed fiber. This method produces strong, smooth-surfaced products. Heat is added to the process at specific stages, allowing the material to have the look and feel of plastic, even though it is made from recycled fibers.
Some products require two steps to complete: forming and finishing. These types of products are considered processed. The unit first completes any of the first three processes and then proceeds to the processing section. Adding color, cutting, trimming, or using additives are all part of secondary processing.