Design For Recycling

1.1. General introduction

Paper is essentially divided into two distinct categories: paper and paperboard. Paper is usually lighter in basis weight or grammage, thinner, and more flexible than paperboard. Its primary uses are for printing, writing, wrapping, and hygiene purposes, although this is just a short list. Paperboard – as the suffix hints – is heavier, thicker and more rigid.

Without paper and board, many of us would not be able to read, teach or learn; convey messages or market our products. We would not be able to ship merchandise, or protect goods, nor improve our lives with personal hygiene products and tissue. Across the world, wood, paper and tissue products touch lives every day and in ways we rarely notice.

Paper was first produced in South Africa in 1920 using imported recycled paper. In 1936, the straw was first used. Today, paper products are made from renewable virgin wood fibre or recycled paper fibre, and in cases using bagasse (sugar cane process waste).

In South Africa, the wood fibre for papermaking comes from sustainably managed commercial timber plantations. Species such as eucalyptus or pine are planted, harvested and replanted – much like farming. Less than 10% of the total plantation area is harvested each year, and replaced with new saplings or regrown (coppiced) in the same year. This means that there are compartments maturing each year, with a sustainable supply of wood for generations to come.

This makes wood (and paper) a renewable resource which stores carbon. Paper is also recyclable, which not only keeps the carbon stored for longer, but also provides paper manufacturers with an alternative source of fibre.

Today, wood fibre arrives at the mill as whole tree trunks, wood chips or paper pulp from other mills. Recycled or waste paper can also be used.

On average, South Africa collects 1.2 million tonnes of recoverable paper* and packaging, each year. (*Recoverable paper excludes paper which is unrecoverable or unsuitable for recycling. For example, toilet tissue and sanitary products, cigarette paper and archive material.)

Find latest paper recycling statistics here

1.2. The Process

The types of raw materials used, and the process employed to make the paper will produce different kinds of paper, depending on what the paper or paper board will be used for.

Each grade of paper has a weight, a processing type and a finish. These factors determine its transparency, appearance, weight, thickness, level of opaqueness, feel and durability. For example, the lifecycle of a newspaper is short. It’s not going to sit on your bookshelf for years, whereas a coffee table will be referred to often and requires a better finish.

The type of printing technology will also determine the type of paper that should be used. 

1.2.1. Fibre

Paper can be made from any fibrous material prepared such as wood, cotton, grasses, etc. Today however it is largely produced using wood. In South Africa, this wood comes from eucalyptus (hardwood) and pine (softwood) trees.

1.2.2. Pulping

At the pulp mill, the logs are debarked and are ground to release fibres for mechanical wood pulp or wood chips are processed for chemical pulp. The objective of pulping is to break down and dissolve the lignin, the natural ‘glue’ that holds the wood together.

1.2.2.1. Chemical pulping

Wood chips are “cooked” in a digester at high pressure with an appropriate solution of chemicals to dissolve the lignin and separate the cellulose fibre bundles into individual cellulose fibres. Since chemical processing is gentle on the fibre, chemical pulps tend to have longer fibres and make strong paper such as printing and writing papers and paperboard. (Lignin is what makes paper turn yellow after a while.)

Paper made from chemical pulp and coated to ensure a smooth surface for printing is called coated fine paper (or wood free paper) and used in the production of calendars, coffee table books, magazines and business reports.

1.2.2.2. Mechanical pulping

Chemicals are not used to remove lignin. Instead, wood chips are pressed against a refiner that mechanically separates the fibres. Mechanical pulps have shorter fibre lengths and produce papers which do not require as much strength.

Paper made with mechanical pulp is used for newsprint, speciality papers, tissue, paperboard and wallboard.

1.2.2.3. Thermomechanical pulping

This is similar to mechanical pulping but takes place under higher temperature and pressure. This softens the lignin even more than can be accomplished using frictional heat, and fibre separation is easier. 

1.2.3. Finishing

Coated vs uncoated paper – What’s the difference?

Coated papers contain a layer of coating material on one or both sides. This “seals” the paper, restricting ink absorption by the paper. The ink can sit on top of the paper, in a crisp defined dot. The coating materials of pigments and fillers help to improve the printing surface of the paper.

Uncoated papers – not coated with a layer of pigment – usually include printing and writing papers made from bleached chemical pulp. They are used for general printing, photocopying and stationery. As they are more porous, the ink will soak into the paper creating a softer, warmer appearance. Uncoated papers can be categorized by type: offset, opaque and text & cover.

1.2.4. Paper recycling 

Paper recycling involves the reprocessing of paper products into new products. The feed stocks would either be post-production/pre-consumer sources (offcuts or rejects from the papermaking, conversion or printing phases) or post-consumer sources, i.e. after a consumer has used it.

Generally, recovered paper is used to make different grades of paper. Recyclable paper and board is separated into 16 different categories which are listed in the Appendix at the back of this section. Paper would be sorted and baled according to grade and processed depending on the type of “new paper” being made. 

The recovered paper is fed onto conveyors where obvious contaminants (e.g. metals, rubber etc.) are removed. The paper is then fed into a pulper – a giant industrial blender – to process recycled paper into a pulp slurry. The pulp is then passed through a variety of screens to extract other contaminants before being delivered to the paper machine.

Paper fibre tends to shorten each time it is repulped and refined. Once paper fibres become too short, they will pass through the sieves and be classed as sludge. It is for this reason that virgin fibre will be added to “boost” pulp recipes and add strength.

According to Kreplin, Schabel and Putz (December 2019), fibres from corrugated boxes can be recycled 25 times without experiencing signs of a “recycling collapse”. Depending on the specific fibre-based product/fibre type and the corresponding recycling processes and losses during recycling, the average number of cycles can be lower. Introducing virgin fibres helps to maintain pulp volume, quality and mechanical properties. (Source: Circularity by Design for Fibre-Based Packaging, 4evergreen)

All manufactured paper is 100% recyclable, such as:

• office paper
• magazines, including glossy magazines
• brochures
• newspapers
• corrugated cardboard
• cardboard boxes such as cereal boxes
• shredded paper (not always recommended as it is difficult to bale and it shortens the paper fibres)

Some paper products are recycled but they may be difficult to recycle or there is limited capacity or technology to do:

• liquid packaging board – milk and juice cartons
• paper cups and containers
• frozen food containers – particularly those with PE coatings
• label release liners and backing papers
• potato sacks and cement bags

Paper becomes non-recyclable when:

• additives for wet strength are used in the paper manufacturing process.
• heavy foils and embellishments are added (i.e. gift wrap; cards, luxury packaging).
• glues are added e.g. some sacks with glued inner sleeves and ‘sticky’ notes.
• wax coating, foil linings or laminates are added to boxes.
• plastic (PE) protective layers are added e.g. tile cement bags, dog food bags.
• when used in a manner that food or automotive oils impregnate (contaminate) the paper.
• when flushed down the toilet, as tissue paper.

Contaminants – or more importantly “non-recyclable materials” – such as those indicated above can affect the reprocessing of the paper. It is for this reason that paper should ideally be kept free from such materials. Considerable research is being done in SA to try to deal with some of these materials. Ideally all players within the paper chain including packaging converters and printers should be mindful of the current constraints.

1.3. Paper grade definitions for recycling

This list of South African Standard Grades of Recovered Paper and Board gives a general description of the standard grades by defining what they do and do not contain.

Refer to the Paper Grade Definitions here.

1.3.1.     Moisture content in recovered paper and board

Recovered paper and board will in principle be supplied with moisture of not more than the naturally occurring level – where the moisture content is higher than 10% on paper and 12% on kraft/board (of air dried weight), the additional weight in excess of the allowed percentage may be claimed back.

Refer to the Moisture Content Guidelines here.