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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 pulp molding are trays used to carry various drinks in fast food restaurants, ladle-type containers and food trays. This type of container has greatly increased in popularity over the last 10 to 15 years as consumers have started to demand recyclable packaging.
There are four types of pulp molding products available to consumers: thick wall, 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, there is a significant amount of water and energy required to create the final product. The great need for resources has led some experts to question whether these products are really better for the environment.
Thick wall pulp molding is used for packaging heavy items, molded pulp pallet trays and auto spare 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 commonly used production method for cellulose molding materials. A mold is created using a very fine wire mesh in the reverse form of the final product. Fibrous materials are sprayed onto the mold, covering it completely; as the material dries, the wireframe is separated from the product and used again. For an example of a product made with this process, look at beverage trays, cup holders, 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 a 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 is then passed to the processing section. Adding color, cutting, trimming or using additives are all part of secondary processing.