- Paper is predominately made from wood fibre which comes from trees.
- 3 to 6 billion trees are cut down per year.
- The paper industry is the 4th largest emitter of greenhouse gases.
- About 35% of municipal solid waste (before recycling) by weight is paper and paper products.
There are two main paper making processes:
- groundwood mechanical process (newsprint, telephone directories)
- kraft chemical pulping process (office copy paper, offset paper, cards) which is about half as efficient as the groundwood process (uses twice as many trees for same about of paper)
Clay or chalk coatings are used in the kraft chemical process. This is between 10-30% of the thickness of the paper. The clay gives it the glossy surface and is great to print on. Clay composts well.
Clay does not recycle well - it must be removed before paper is recycled. It can clog recycling machines however the clay does help to remove ink from paper fibres. Clay is obtained by open pit mining.
"Sizing" is added to make paper more water resistant. Sizing can be starch, polymer or rosin. This is used in all paper but in large amounts in packaging and frozen food products.
Starch is also used to add stiffness and strength to paper. It is obtained from starchy crops and the waste of some food crops. It composts well and can be easily removed during recycling.
Polymer is used to add "wet strength" this makes paper stronger even when it is wet. Photographic paper, filters, paper towels and food containers can all have added polymers. These compost slowly however due to their water repelling properties may add difficulty in the paper recycling process. Most of these polymers are manufactured from crude oil.
Acid free paper is paper with a neutral pH. Manufacturing acid free paper helps preserve the paper as acid rich paper goes yellow and breaks down over time.
The paper is usually treated with calcium bicarbonate to neutralise natural acids in the wood. Pine trees tend to be more acidic.
Most commercial paper is acid free. This is the result of using chalk rather than china clay as the main filler. All sizing agents, inks and finishes should also be acid free.
Alkaline paper has a very long live expectancy, the manufacturing waste is more environmentally friendly and the paper is more easily recycled.
Bleaching agents are used to increase the brightness and make paper whiter. Bleaching uses chemical agents such as hydrogen peroxide, sodium dithionite and chlorine. Conventional bleaching using elemental chlorine produces and releases into the environment large amounts of chlorinated organic compounds, including chlorinated dioxins which are toxic. Many modern manufactures use ECF (Elemental Chlorine Free) and TCF (Totally Chlorine Free) bleaching processes to reduce the release of chlorinated organic compounds. Look for TCF if using virgin wood paper or PCF is the paper includes recycled content (check out the quick guide to recycled paper for more info).
These are applied over the ink and dried by exposure to UV light. They have a high gloss and can be applied to spot locations and in very thin films. They provide a strong UV protection to the underlying ink and provide water resistant properties.
UV coatings are usually made of acrylic polymers that are manufactured using highly toxic substances. Some UV coatings are made from soybean oil rather than crude oil. UV coatings are not easily recycled and in landfills they are not readily biodegradable.
Celloglaze is a super thin laminate film which is lightweight and flexible and is stuck to the paper using both heat and pressure. Celloglazing or plastic lamination can be matt or gloss and can be single sided or double sided. Celloglaze is not recyclable and not readily biodegradable.
Varnish is a press coating - that means that during offset printing it is printed just like a process or spot colour. Varnish is basically ink without the pigment. Like UV coatings these can be applied to spot locations. Varnish has the same effect on paper recycling as ink and can be handled by all paper recycling systems. Varnish does not work well on uncoated paper.
Aqueous coating is more environmentally friendly than UV coating because it is water based even though they are still generally made from acrylic polymers. Aqueous coatings do not seep into the press sheet as much as varnish and does not crack or scuff easily. Aqueous does, however, cost a lot more than varnish.
Aqueous coating is generally laid down in a single layer (like celloglaze) not to localised spot locations like varnish. Aqueous comes in gloss, dull, and satin.
Recycled paper is made from either pre-consumer waste (waste fibre from paper mills that never reached the consumer) or post-consumer waste (the fibre that is made from recycled office and home waste).
Post-consumer waste content is considered better than pre-consumer because it is more likely to end up in landfills if it is not reused.
Check out the sustainable designers quick guide to recycled paper for more information.
Tree free paper can be made from:
- Agricultural residue (sugar cane)
- Fiber crops (hemp, kenaf, jute, flax)
- Textile wastes (a small percentage)
- Wild plants (Sisal, bamboo)
- Specialist papers (elephant dung)
Multi-laminates are used for packaging and cartons and are also called aseptics, brick pack or tetra paks. They have a complex layer structure composed of plastic polymer (20%), aluminium foil (4%) and paper fibre (75%). They are usually used for food packaging as they are water proof, strong and have a good shelf-life. Due to the plastic polymers and foil they are not readily compostable. Special equipment is needed to separate and recycle the fibre layers. The paper layer in laminates is made from strong, high-quality virgin fibre. Because of this, tissue mills are the top customer for recovered laminates, since tissue must be made of strong fibre to meet necessary performance characteristics.
Waxed paper provides water repellant properties and is used for food and drink containers however due to problems with the wax affecting recycling plants these papers are generally not recycled. Wax paper will compost well.
For additional information on paper packaging and sustainability download this 66 page pdf from www.greenblue.org
Check out the sustainable designers quick guide to recycled paper for more information about recycled paper, chlorine-free paper and sustainable forestry practices.
Stay tuned for the sustainable designers quick guide to ink & adhesives coming soon.