Paper packaging’s dirty secrets – how to go plastic free, find alternatives to toxic PFAS, and avoid recycling and composting issues.

Paper is an incredible material that has been around since the Han Dynasty in China. While little has changed in its structure and the way we use it, there have been developments in the synthetic chemistry we combine with it. In some cases, these substances have impacted on the beauty, biodegradability and toxicity of paper. Derived from natural fibres, such as wood pulp, hemp, cotton and bagasse, regular paper is held together by nothing more than the natural binders present within the fibres. To make paper resistant to water, grease and oil — qualities necessary for packaging wet or greasy food — additions are required. Traditional greaseproof paper uses natural waxes. But in the case of mass-produced paper, the most common solutions are lamination and coating.

Laminated paper packaging has a plastic or aluminium lining, which means that as soon as it’s put in your hand it’s destined for landfill or incineration. Some paper mills can handle paper with plastic coating on only one side. The paper is re-pulped and plastic filtered out and burnt for fuel. If there is plastic on both sides, then this is not possible and the material is incinerated. It is estimated that <0.5% of plastic-lined beverage cups are recycled, for example. Without a plastic barrier, the paper would absorb the liquid contents and start to soften and fall apart. So-called ‘plastic free’ versions exist, but these often use polylactic acid (PLA) bio-based plastic instead of polyethylene (PE) for the liner. While PLA bioplastic is better in some ways (lower environmental impacts in terms of fossil fuels depletion and climate change) and is industrially compostable, it is not home compostable or able to breakdown in landfill or sea water — it needs high temperature and humidity such as found in industrial composting facilities. Another consideration is that a thicker film of PLA is required to provide the same performance as PE, typically in the region of 30 g/m2 versus 15 g/m2.

Paper coatings designed for food contact, or as a barrier layer, typically contain polymers such as acrylic (polyacrylate) or polystyrene (PS) in a water-based (aqueous) dispersion. From 2023, the EU Single Use Plastics Directive (SUPD) stipulates that these coatings can no longer be referred to as plastic free. As a result, products with this finish, the same as laminated paper and card, must must display a ‘Plastic in product’ logo. While they are a lot lighter than laminated types, in the region of 5-10 g/m2, the coating soaks into the surface and so can present some problems end of life. When the paper is broken down, such as in recycling or composting, the coating sticks to the fibres and is shed as microplastics. It may evade the legal definition of plastic in some places, because it doesn’t contain very much by weight, but this doesn’t mean it is plastic free.

Per- and polyfluoroalkyl substances (PFAS) have been added to paper and board since 1950s to provide barrier properties to fat, grease, staining and water. They have become very popular due to their effectiveness and relatively low price (traditionally up to one third cheaper than non-PFAS solutions). Applications are particularly targeted around fatty foods, where the product will be heated in the packaging, or for longterm storage of food. Examples include takeaway food containers, fast food packaging, ice cream and chocolate wrappers, baking papers and bread and pastry packaging.

The problem with this is PFAS are toxic and extremely persistent in the environment and human body, especially perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The eye-opening documentary, The Devil We Know, directed by Stephanie Soechtig looks at allegations of health hazards from these chemicals, in particular around the Dupont Teflon manufacturing facility in West Virginia, US. PFAS chemicals do not breakdown, cannot be recycled, and cannot be composted. In fact, if they get into compost or recycling systems they too will become contaminated. They are considered so dangerous that production has been phased out, or is being phased out, in many regions and countries, with several companies stopping production. Having said all that, it can still be found in everything from your underwear to food packaging.

Silicone is being used more and more in the kitchen, and provides an alternative for non-stick applications, such as baking ware and coated paper. Made up of polysiloxane (silicon-oxygen backbone), it is very stable, more so than conventional hydrocarbon polymers (carbon-carbon backbone). It has exceptional resistance to chemicals (except strong acids), weathering and extreme temperatures. However, silicone is not without its potentially harmful drawbacks. It is a polymer that may contain residual siloxane are curing. There is also the risk that siloxanes are released as a result of repeated heating and through surface abrasion.

Plastic free paper packaging

Not all paper and moulded pulp is toxic and killing the planet. While there’s plenty of shifty chemistry going on, driven mainly by cost, a handful of companies are pushing some really nice sustainable solutions, as well as age-old solutions that provide very effective barrier properties.

Micro fibrillated cellulose (MFC) provides a physical alternative to PFAS. It is produced from intensively refined wood pulp, which creates a densely compressed network of cellulose fibres with pores much smaller than conventional paper. This helps to provide a barrier to water and grease. The small size of the cellulose fibres also reduces light scattering, resulting in a translucent material. An example is Sylvicta paper by Arjowiggins.

Notplaand Kelpi produce compostable seaweed-based coatings that provides a barrier to oxygen, water and grease. Suitable for food packaging, these innovative coatings can be disposed in paper recycling, or composting bins where seaweed bioplastic degrades like fruit peel. See also What the kelp! Innovative materials from seaweed.

Solenis produce a number of barrier formulations which are suitable for food packaging and are either water-based synthetic biopolymers or vegetable-oil based bio-waxes. Zume and Solenis teamed up to create a line of PFAS-free packaging that is compostable and made from repurposed natural materials like agricultural waste. Internal sizing agents, such as alkyl ketene dimer (AKD), can be used in conjunction with these products to create a more effective water barrier.

Siegwerk’s Uninature water-oil barrier coating for disposable paper packaging is 100% bio-based and proven to effectively reduce the absorption of water, oil and grease on paper stock intended for direct food contact while maintaining its recyclability.

Vegetable parchment paper, used in baking as a non-stick and disposable grease-resistant surface, is made from paper that is passed through a bath of concentrated sulphuric acid. The cellulose reacts with the acid, and the fibre almost melt together, to form a dense and impermeable surface with a small number of pores. It is highly resistant to water and grease, and suitable as a food wrapper and liner. To improve barrier properties and reduce air permeability, greaseproof papers are coated with wax, starch, carboxymethyl cellulose (CMC) or polyvinylalcohol (PVOH). Starch closes the surface of the paper and reduces the air permeability and can in this way also improve the water barrier performance.