Is wool biodegradable? Can it be composted? Mostly…

  • Date: May 13, 2022

As humans, we have been using wool for thousands of years. And you can see why – its warmth, softness and breathability make it suitable for a lot of different items. But what about when it comes to the end of its usable life – is wool biodegradable and fit for the compost pile? Usually, as long as it is pure wool and not a synthetic ‘wool’ blend. Let’s find out more…

Firstly, where does wool come from?

Understanding where an item comes from is the first step in determining if it is biodegradable (and generally eco-friendly) or not. Its origin holds different clues.  When we think of wool, we most likely strike up an image of fuzzy sheep fleece. However, wool can come from different animals – if an animal has hair, wool can be made. Wool from goats, camels and alpacas are amongst the most popular.  Although these wools have different qualities, they have one thing in common – they are all 100% natural.

So, is wool biodegradable?

If an item is biodegradable, it can be broken down naturally by bacteria and/or other microbes. Wool is a natural material and by the process of biodegradation can return its components to nature. Under suitable conditions it can breakdown in a matter of months.

However, wool is often blended with synthetic fibers such as polyester. This gives the fabric increased versatility but will also save you money. However, in terms of biodegradability, it is not good news! Polyester, and other synthetic fibers such as nylon, are not biodegradable. They will simply break up into smaller pieces over time and, rather than providing nourishment to nature, can cause havoc.

Is wool compostable?

Composting is a great way to reduce the amount of household waste that you send to landfill. Not only that, but you will also produce some homemade, nutrient-rich fertilizer too! However, contrary to what many people believe, just because an item is biodegradable does not mean it is automatically qualifying for the home composting pile. If may, for example, contain certain chemicals that may do your garden more harm than good. On the other hand, to be compostable, an item must be biodegradable! We can rule out wool-synthetic blends straight away. They are, unfortunately, a no-go when it comes to composting.

Pure wool, however, can be composted. As with other natural fibers such as hemp and linen, it makes a great carbon-rich ‘brown’ ingredient to add to your pile. As with all composting endeavours, it is important to ensure you have a suitable mixture of both ‘browns’ and nitrogen-rich ‘greens’, such as food scraps and urine(!), in your compost pile. You might need to do a bit of experimentation and adjust as you go, but we find a simple 1:1 ratio effective. Just be sure to monitor it – a shift away from a suitable ratio will show tell-tale signs such as dryness or bad odor. If you are new to the composting game, have a look here for some top beginners’ tips.

Some considerations when composting wool…

Before adding a woolen garment/item to a compost pile, you must consider how it was cleaned in its usable life. For example, clothes that have been regularly dry cleaned will likely have remnants of chemicals that you don’t want in there. Unwanted chemicals can cause havoc. They can contaminate the pile and, ultimately, end up in amongst your produce. Some people still add these but only add the end-product to non-edible plants. However, as always, it is your call – don’t ever add anything that you feel uncomfortable with.

You can speed up the process a little by cutting the woolen item into smaller pieces. In addition to providing a larger surface area for the bacteria to munch on, it will also allow you to mix the pieces evenly within the pile and share its carbon-richness as it goes.  Although, not essential, it will speed up the process a little bit.

The bottom line

Composting is a great way to divert some of our household waste to landfill. We always recommend reuse and gifting in the first instance, but if this is not possible composting is a suitable alternative. Just make sure that the ‘wool’ is actually wool! If blended with any synthetic materials, it will only partially break down in the pile. The wool part will biodegrade but the polyester/nylon will just fill your pile with harmful microplastics.