At least 40 million tons of used papers enter US paper recycling plants annually. Used paper is supplied by offices and households across the country. But do you know how our paper mills effectively rid used paper of ink in order to maintain recycled paper color quality, specifically for laser printing? Since about 67% of waste paper is used as raw material for recycled paper, imagine what it could do to the final product if ink not totally eliminated. When traces of ink find its way into the recycling process, paper would be left with a grayish tint that would make it unacceptable for use as regular media, much more as a substrate for laser printing.
Basically, waste paper (newspaper and office papers) undergoes 2 basic processes to rid its surface not only of ink but also of loose materials such as wires, paper clips, plastic pieces, staple wires and so on before recycling can commence.
Washing. Bales of waste paper reaching paper mills are fed into a large pulper filled with process water which turns waste paper into a slurry (looks more like porridge than pulp). And when repulped material flows through the centrifugal screens; loose materials like wires, paper clips, staple wires, plastic pieces and other impurities are literally thrown out of the slurry. Most of the water is drained out of the slurry through minute screens or sieves that allow water to pass through - not the pulp.
Flotation. Shredded waste paper is again turned into a slurry in the process of removing contaminants. Formulated chemicals classified as surfactants are then added to the slurry; thereby forming a sticky lather on top of the pulp. Air bubbles are then introduced through the pulp which trap the ink, allow it to float into the surface and are then immediately removed. Care must be observed in the speedy removal of air bubbles because if the bubbles break in the process, ink will simply return to the pulp.
From here on, additives are integrated with waste paper pulp to sustain paper quality, color and surface character before being placed over a moving screen to rid it of water. The resulting semi-dry pulp passes through the giant rollers to squeeze out whatever water is left and then the almost dry web enters the dryer before the sheets are formed into rolls ready for use.
When recycled paper does not pass the stringent paper manufacturing process, it could not be used for laser printing - not even with a generous supply of toner powder from a compatible toner refill kit
