Are paper bags biodegradable? Can they be composted?

  • Date: August 1, 2022

Many brands have switched to paper bags in an attempt to reduce their environmental impact. Demand has increased significantly in the last couple of years, as we try to reduce our plastic use. Paper bags are biodegradable and compostable.  But, to improve their function, they are often coated with other non-biodegradable materials making them unsuitable for your compost pile. Here we will take a close look at the different paper bags and their ability to be composted.

What are paper bags made of?

When trying to determine if an item is biodegradable or not, knowing what it is made from is a good place to start.

The main material of a paper bag is paper – most commonly recycled paper but also, in some instances, fresh stuff derived from wood pulp. However, paper on its own isn’t the most durable, especially if is being used for carrying sizable items or hot/greasy foods. To provide improved functionality, it is often coated with other materials such as plastics, wax or foil.

So, are paper bags biodegradable?

Biodegradable items can be broken down in suitable conditions by micro-organisms such as bacteria. Generally, if an item is from a natural source, it will be biodegradable. Essentially, this process allows the component parts of a natural material to return to nature. Paper bags, and paper in general, will tend to biodegrade in a matter of months.

It should be noted that suitable conditions are key. Many people think that biodegradable items will biodegrade in the given timescales in landfill. This is not the case. Landfill sites are often packed with objects, making airflow and moisture limited – the breakdown process will take significantly longer in these conditions. This is why diverting any items from landfill, even biodegradable ones, is so incredibly important!

Are (uncoated) paper bags compostable?

Composting can be a great way of ensuring items don’t end up in landfill – it can decrease the amount of waste your household produces by a significant amount. And, at the same time, provide you with some homemade fertilizer for your yard.

You may well think that if an item is biodegradable that it can be composted too. This is not always the case. To qualify for the compost pile, an item must be biodegradable. However, if a biodegradable item is, say, saturated in a harsh chemical or contains biological waste, it would be deemed unsuitable. It could contaminate the pile and, ultimately, the final compost product. In short, all compostable items are biodegradable but not all biodegradable items are suitable for the compost pile!

Paper bags (unless somehow saturated with a hazardous substance) are perfectly suitable for the compost pile. Although paper bags are not the most nutritious composting ingredient out there, they make a great addition due to the other benefits they bring. As well as adding some much needed carbon-rich ‘browns’ to the ratio, they can also provide a bit structure to the pile. Pockets of space between paper and cardboard items help ensure that the air can flow freely through the pile. Paper can also soak up excess moisture, reducing the chance of bad odors.

All in all, uncoated paper bags are a great addition to a home compost pile – and they won’t hang around for too long either!

Are coated paper bags compostable?

Coated paper bags can be compostable – but in most cases they contain synthetic materials such as plastic and foil. Only natural substances can break down by biodegradation and return their components to nature. Synthetic substances will break down over many years, but not in the same process. Plastic, for example, will simply breakdown into smaller and smaller pieces which can cause problems in the environment rather than the nourishment that a biodegrading item does.

Wax coated paper bags, in some instances, will be biodegradable and suitable for composting. So long as the wax is from a natural source, such as beeswax. Those coated with paraffin wax (unfortunately, by far the most common currently available) can not be popped in the compost bin. Paraffin wax is not biodegradable.  

Things to consider when composting paper bags

Paper bags will breakdown in a matter of months in a healthy compost pile. However, you can speed up this process a little. Simply cut, or rip, the paper bag into smaller pieces. This will benefit the pile for two main reasons. Firstly, it will provide a larger surface area for the microbes to munch on. Secondly, it will allow you to spread the pieces throughout the pile – taking its carbon and moisture-wicking abilities as it goes.

You may also have noticed that paper bags sometimes have a string/twine handle – this is particularly commonplace in gift bags and retailer paper carriers. Sometimes the string contains synthetics that will not biodegrade. In that case, the handle should be removed before popping the bag in the compost pile. However, sometimes the twine is made from a natural resource such as hemp or jute. If this is the case, these can be added as a carbon-rich ‘brown’ item too.

The bottom line

Paper bags are a little more complicated than their name suggests. The coated variety may well ensure improved functionality, but it also causes havoc when it comes to their disposal. Standard, uncoated paper bags add a carbon-rich ‘brown’ element to your pile. But, unfortunately, most coated types can’t be composted due to containing non-biodegradable materials. Try to re-use them as many times as possible and then pop them in the trash. As always, long-term re-usable options (such as jute shopping bags) are the best option where practical.