Recycled or biodegradable polythene: which should you specify?

What does recycled content actually mean on a polythene specification?

Recycled content on a polythene specification is the proportion of the film, measured by weight, that comes from reprocessed plastic waste rather than newly made polymer. Two very different sources sit behind that number. Post-consumer recyclate reached an end user, was used and was collected back: household and commercial waste film, carrier bags, agricultural film. Post-industrial recyclate, sometimes called pre-consumer, is factory material such as edge trim, offcuts and reject reels.

Post-consumer material is harder to source, more variable and usually darker, having been through use, collection and washing. Post-industrial material is cleaner and runs more consistently batch to batch. The environmental argument favours post-consumer, since that material was genuinely heading for disposal, while much factory scrap would have been fed back into production regardless.

Ask any supplier which of the two they are quoting, and get it written on the specification, not agreed on the phone. We have manufactured polythene since 1996 and we extrude and convert in house at Blackburn, so we can tell you what is in the film we make. We offer recycled options across much of our range, including refuse sacks manufactured from post-consumer waste.

What do biodegradable and compostable actually mean?

Biodegradable means a material is designed to be broken down by living organisms over time. Compostable is narrower: the material breaks down into compost under defined conditions, within a defined period, leaving no harmful residue. Everything compostable is biodegradable, but much of what is sold as biodegradable would never pass a composting test.

In polythene packaging there are broadly three families. Conventional polyethylene carrying a pro-degradant additive, usually described as oxo-degradable, is designed to fragment under heat, light and oxygen; it has attracted serious criticism for breaking into small pieces rather than fully degrading, and has been restricted in some markets, so check the current regulatory position before specifying it. Films built on compostable polymers such as starch blends and PBAT-type materials are a different chemistry from polythene, and are the grades composting certification schemes cover. Additive-based biodegradable polythene sits between the two.

Ask your customer or retailer to state in writing which of these they require and what evidence they expect, then specify that. "Make it biodegradable" is not a specification, and two suppliers can answer it with completely different materials.

How does recycled content change the way the film performs?

Recycled content changes three things about a polythene film: colour, consistency and strength. Colour is the most visible. Recyclate carries the colour of whatever it was in its previous life, so high recycled content is easiest in black, grey, green or another pigmented shade. A genuinely clear film with high recycled content is difficult, and clarity is usually the first property given up.

Consistency is the second. Reprocessed material can carry traces of contamination that show as specks or gels, and feedstock varies batch to batch. Filtration and grade selection manage most of it, but a very thin gauge shows every defect, so recycled content sits more comfortably in medium and heavier gauges.

Strength is the third. Polythene that has been through one heat history tends to lose a little impact and tear resistance against an equivalent virgin film. Two things address that: a modest gauge increase, or a co-extruded structure with a recycled core between virgin outer layers, keeping recycled content high with a cleaner sealing surface. Ask for a trial run on your own line rather than judging from a sample.

What changes when you switch to a biodegradable or compostable film?

Four practical things change when a pack moves to a biodegradable or compostable film: storage life, mechanical performance, sealing behaviour and the waste route. Storage life is the one most often missed. A film designed to break down starts its clock the day it is made, so order to a realistic usage rate, store it cool, dry and out of sunlight, and rotate stock. Holding a year of buffer stock is a mistake.

Compostable polymers are a different chemistry and do not always behave like polythene at the same thickness. Moisture resistance is usually lower, some grades are stiffer and noisier while others are softer and tackier, and the sealing window on a form fill seal machine often needs resetting. Take a trial reel and let your operators settle the machine before committing to a full run.

The waste route decides whether any of it was worthwhile. Compostable film only composts where a collection accepts it and sends it somewhere that composts it, and UK provision is patchy. If your pack ends up in general waste, you have changed the material and the cost without changing the outcome.

How does the Plastic Packaging Tax affect the decision?

The UK Plastic Packaging Tax works on recycled content, not on biodegradability. In outline, plastic packaging components made in or imported into the UK are chargeable where the recycled content, measured by weight, falls below a set proportion, and businesses handling more than a set weight of plastic packaging over a defined period must register. The rates, proportions, thresholds and detailed rules are published on gov.uk and do change, so take your figures from there or from your accountant, not a supplier's brochure.

The point that catches buyers out is that biodegradable and compostable films are still plastic packaging for tax purposes. Moving from conventional polythene to a compostable film does not, on its own, take a pack out of scope. Recycled content is the lever the mechanism actually responds to.

You will also be expected to evidence recycled content you claim, so keep the specification and paperwork from your supplier. Ask at quotation stage what recycled content an item can carry and whether it can be documented. Call us on 01254 691354 or email sales@morepolythene.co.uk and we will tell you what is achievable on your product.

Which one is right for your application?

Recycled polythene is the stronger choice for refuse sacks and bin liners, pallet covers, shrink film, layflat tubing, sheeting and most industrial or back of house packaging. These are items where a grey, black or coloured film is fine, the gauge is heavy enough to carry recyclate, and the used pack is often collected back through a film recycling stream.

Biodegradable or compostable film earns its place where the pack is unavoidably contaminated with food or organic matter and cannot be recycled as film, in horticulture and growing where the item ends up in the ground, and at events or sites running a single composted waste stream. It is also the answer when a customer or retailer has mandated it in writing.

Neither is right when the driver is vague. If nobody can say where the pack goes after use, start there rather than with the material. Our product selector tool narrows the range by application and format, and we will quote a recycled grade and a biodegradable grade from the same brief so you can compare like for like.

Is there a third option worth considering first?

Yes. Before choosing between recycled and biodegradable polythene, check whether the pack needs as much material as it currently uses. Taking a bag down from a gauge it does not need to one that still protects the product removes plastic from every unit, cuts what you pay per thousand, and reduces the plastic packaging weight you are accountable for. It is the only route that improves the environmental position and the cost at the same time.

Downgauging carries risk and should be tested, not assumed. Product weight, handling, hand or machine filling, transit distance and how it is stacked all decide how thin you can safely go. Our polythene thickness converter helps when comparing quotes written in microns, gauge and mil, and a short trial run tells you more than any specification sheet.

In practice the strongest answer is usually a combination: get the gauge right first, add recycled content second, and use biodegradable material only where the end of life route genuinely supports it. We manufacture all three in Blackburn and would rather quote the one that suits the job than the one that sounds best.

Frequently asked questions

Is biodegradable polythene better for the environment than recycled polythene?

Not automatically, and frequently not. Biodegradable and compostable films only deliver their benefit if the pack reaches a waste stream that genuinely composts it, and in the UK that provision is patchy. Recycled polythene reduces demand for new polymer on every unit produced and can normally be recycled again, so for most industrial and retail packaging it is the more dependable choice.

Can compostable bags go in the same recycling stream as polythene?

No. Compostable film is a different polymer and it contaminates polythene film recycling, so a compostable bag dropped into a store film collection point or a baled film stream creates a problem rather than solving one. Keep the two routes separate, and label the pack clearly so whoever disposes of it knows which route it belongs to.

Does switching to biodegradable packaging reduce Plastic Packaging Tax?

No, not by itself. The UK Plastic Packaging Tax mechanism is based on how much recycled content a plastic packaging component contains, and biodegradable and compostable films are still treated as plastic packaging. Increasing recycled content is the change that affects your position. Check gov.uk for the current rates, proportions and registration rules, as they are updated.

Why is recycled polythene usually grey, black or coloured?

Recyclate carries the colour of whatever the material was in its previous life, and blending many sources together produces a grey or mottled base. Pigmenting the film black, green, blue or another strong colour hides that variation and gives a consistent finish. Clear film with high recycled content is much harder to produce, which is why clarity is normally the first property traded away.

How much recycled content can a polythene bag contain?

It depends on the product, the gauge and how the pack has to look. Refuse sacks and heavy duty industrial film can carry a high proportion of post-consumer material, while clear presentation packaging and very thin gauges carry far less before appearance or strength suffers. Tell us the item, the gauge and what it has to do, and we will tell you what is realistic before you commit to a specification.