The ABCD system
Up to a few years ago the National Association of Paper Merchants (NAPM) used
a classification system to identify the proportion and source of waste
fibre used to make recycled paper, which used the letters A to D,
each letter accompanied with a figure indicating the percentage of
that source. It was a useful system because it is important to understand the differences between
these four sources of waste.
A: Mill broke
This is pulp which has been on the papermaking machine but not turned
into saleable paper. It has virtually the same properties as virgin
wood pulp and has always been re-used by paper mills - indeed it could
be argued that it is not a waste product at all. Consequently the
NAPM scheme does not recognise a paper as recycled if it contains
more than 25% mill broke and/or virgin wood pulp. The longer fibres
in mill broke are used to increase the strength of a paper.
B: 'Woodfree' unprinted waste
The term 'woodfree' causes the most public
confusion, as the paper is anything but 'wood-free'. The name indicates
that when originally pulped the 'woody' lignins in the timber were
destroyed in a chemical reaction (part of the environmental problem
of conventional papermaking), to produce a higher quality paper. If
not removed, the lignins - the inflammable part of the wood - cause
paper to yellow and become brittle with age (as, for example, old
newspapers do). You can see exactly the same process in the way pine
furniture changes colour with age.
Category B waste comes mainly from paper mills and converters, for
example reel and guillotine trimmings, and has not been printed or
'used' in the generally accepted sense.
C: 'Woodfree' printed waste
This comes nearer to most peoples idea of what recycled paper should
be made from, but because it should only include woodfree paper, it
tends to come from limited specific sources, for example, scrapped
work direct from printers or discarded paper and envelopes from offices
of very large companies.
Some would argue that the chief sources of category C waste should
themselves be using recycled paper, and that recycling this it is
only a cosmetic solution. On the other hand some newer, longer fibre
is essential in producing high quality recycled paper, and this is
the most appropriate source for making the very best recycled qualities.
Ink in category C waste is either removed by a cleaning process which
chemically 'floats' it off or by dispersing it throughout the pulp.
The latter is environmentally preferable, but makes the paper less
white and so (to the uneducated!) less attractive.
D: Mechanical and unsorted waste
Mechanical paper pulp is more frankly named - the wood is pulped by
a combination of heat and maceration, but because it retains the lignins
it is only really suitable for short-term uses - for example newspapers
and directories. The lignins present in category D waste can survive
into recycled paper made from it, unless the pulp is retreated to
remove them. Consequently some fading of colours or yellowing when
the paper is exposed to daylight over time make recycled paper containing category
D waste more suitable for uses such as photocopies which are filed,
or for other items with a more limited life.
Category D covers almost all domestic waste paper, including that
collected by councils, local recycling centres and paper banks, and is largely
used in making packaging materials (brown paper and cardboard boxes
for example). Some of this type of waste is used in making the cheaper
recycled office copier and similar types of paper.