Wine corks seem to be one of those items that we throw in the trash without thinking. Recycling is an option, but not, generally at the curbside. What about composting? This totally depends on the type of wine cork. Whilst natural wine corks can be added to the pile, synthetic corks cannot. Here we will have a closer look…
Firstly, what are wine corks made of?
Wine corks come in two main forms – natural and synthetic. Natural wine corks are made of cork (unsurprisingly!). Cork is an extremely sustainable natural material that comes from the bark of the cork oak tree (Quercus suber). It is lightweight, waterproof and durable – making it a great material for lots of items, including wine corks.
Synthetic corks, on the other hand, tend to be made from standard plastics (derived from fossil fuels). You should be able to tell the difference from natural corks – synthetic corks tend to a have a foamy/plastic-like texture and look more uniform than natural cork.
Are wine corks biodegradable?
Before we determine if an item is compostable, we need to know if it is biodegradable. If an item is biodegradable, it can be broken down naturally with the help of micro-organisms such as bacteria. Its component parts can, essentially, return to nature and provide nourishment, rather than cause harm. However, to be biodegradable, an item must have come from nature to begin with.
As follows, natural wine corks are biodegradable – they may take a while to break down, but they will get there. Synthetic wine corks, like all plastics, are not biodegradable. Instead, they will break down into smaller pieces over time which can cause harm to the environment (this is a different process from biodegradation).
It is important to note that although natural wine corks can break down by biodegradation, the conditions need to be suitable. Many people assume that an item will biodegrade in landfill in the quoted time frame for breakdown. Unfortunately, this is (generally) not the case. In landfill, items are usually packed closely together, there is simply no space for all the new items that are being continually added. The lack of airflow and moisture can slow down the process significantly. This is the reason we always advise reusing items and diverting them from landfill for as long as you possibly can – even biodegradable ones like natural wine corks.
So, are wine corks compostable?
Composting is, in essence, biodegradation carried out in optimal conditions. It allows us to dispose of household waste and create a nutritious fertilizer for our garden.
To be compostable, an item must be biodegradable. This rules out synthetic wine corks straight off. Natural corks, on the other hand, can be added to the compost pile since they came from a natural source.
Composting ingredients fall into two categories. ‘Green’ materials refer to items that are rich in nitrogen such as food scraps or even urine (!) ‘Browns’, conversely, are rich in carbon and include items such as newspaper and natural fabrics like linen. Natural cork falls into the carbon-rich ’browns’ category. It is important to ensure you have suitable proportions of both ‘browns’ and ‘greens’ in the mix. Too much carbon-rich material can mean a dry and ant-infested pile, whilst too many ‘greens’ can result in a slimy (and rather smelly) mess! Some experimentation is required, but you won’t go far wrong with a 1:1 ratio. Monitor it and make changes as you go.
Find out more about composting here.
Some considerations when composting wine corks…
When adding ingredients to the compost pile, the size of pieces will have an impact on how long they will take to break down. To ensure that the wine cork decomposes in optimal time, you should cut/grind it into small pieces if possible. This allows it to be mixed within the pile, spreading its carbon goodness as it goes and gives the bacteria a greater surface area to work on.
You should also ensure that the wine cork has not been in any contact with hazardous chemicals or other items that are unsuitable for composting (e.g., glues – if you have been using them for crafts). This would, perhaps, contaminate the pile and have a detrimental effect on plants that the final fertilizer product is used on. If in doubt, don’t add it!
The bottom line
Composting is a great way to cut back on household waste heading for landfill. The ability of a wine cork to compost depends entirely on what it is made from. Natural wine corks are suitable for the pile and provide some much-needed carbon. Synthetic corks, conversely, are not biodegradable or suitable for composting. Re-use or recycling is your best options to divert these from landfill.