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What Is Molded Pulp?

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  • Written By: Mark Wollacott
  • Edited By: Lauren Fritsky
  • Last Modified Date: 08 April 2014
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    Conjecture Corporation
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Molded pulp is a type of packaging material made of recycled and pulped paper. First invented in 1903 in America, molded pulp is a thick, cardboard-like material. It is a cheaper and more affordable alternative to plastic containers. Such pulped containers are also more environmentally-sustainable and, unlike their plastic counterparts, can be recycled.

The pulp can be made from materials such as recycled paperboard, cardboard and newspapers. In fact, any paper-based product can be used. This includes items already made out of molded pulp that have finished their usage and need to be recycled once more. The only products that cannot be used for pulping are those that contained or came into contact with unsanitary materials such as chemicals and bodily fluids.

There are four basic types of molded pulp in existence. Thick-walled molded pulps has rough edges and is used for transporting goods from one place to another. Transfer molding is a thinner version of the thick-walled mold and is smoothed or finished on at least one side. The thermoformed fiber mold is a heated mold created using three-dimensional molds and vacuum forming. The final type, processed pulp, takes one of the three other forms and finishes it by adding printing, a coating layer or sometimes seeds.

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The exact process for making a molded pulp varies depending on the function and the size required. The creation of the pulp itself is a process common to all kinds. In fact, the basic pulp can be used to create all four of the basic types. The paper products are fed into a pulper that mashes the products up into small pieces. Hot water is then added to create a semi-liquid mush. The pulp is then fed through a filter to get rid of any non-paper materials such as plastic.

Molded pulp used to make products such as egg boxes and drink carriers are poured onto lubricated metal molds. A vacuum pump then sucks the pulp down onto the mold to produce an even spread of pulp across the mold. Once formed, the pulp is then put into an oven to dry. The amount of time a pulp mold is dried depends on the size and thickness.

Disposable urinal bottles are another product made out of pulp materials. The process is a little different, as a chemical is first added to the pulp mixture that makes the final product watertight. The mold is made by dipping the mold into the pulp mixture, then sucking off excess water. They are then dried and coated.

Pulp products are better for the environment than plastic. As well as being biodegradable, they are fully recyclable, with the exception of products like the disposable urinal bottles. Pulp containers are also better for animals as they do not cause choking and break up when soaked in water.

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