How is ink removed from paper for recycling?
Sometimes the ink is not removed from the paper when it is processed but is allowed to disperse into
the pulp, discoloring it slightly – which is why some recycled paper can have a grayish or brownish tinge.
However, all of the recycled papers we recommend for printing are de-inked and of a conventional
whiteness. If the paper is to be de-inked, this can be done in one of two ways, by washing, flotation or a
combination of both methods:
1. Washing - As the paper is pulped, soaps are added which separate the ink from the paper and allow it
to be washed away in water which can then be cleaned and re-used.
2. Flotation - Air is passed through the pulp, producing foam, which will hold at least half of the ink and
can be skimmed off.
Sometimes the pulp is also bleached; hydrogen peroxide is most commonly used as it breaks down into
water and oxygen on disposal, although chlorine bleach is sometimes still used.
Although the de-inking process uses water and chemicals, it is still less harmful to the environment than
the manufacturing process of making new paper. |
