Last year, I punctured my road tubeless setup and, in the process of fitting a spare inner tube, left a load of sealant all over the pavement.
This ordeal happened under the watchful eye of a friend who investigates the effects of pollution incidents in waterways for the Environment Agency (honestly!).
His chiding and a sense of guilt over the pollution I may have caused led me to question the impact of tubeless sealant entering the environment.
On the mountain bike side of things, tubeless setups have been the de facto standard for years for riders who don’t enjoy getting punctures. Tubeless tyre technology is also gaining ground in the road world, increasing the amount of sealant sloshing about, and potentially being spilt, from tyres.
So, I wondered, what happens when tubeless sealant is released into the environment? How does tubeless sealant degrade? Are the particles in tubeless sealant biodegradable?
To find out, I approached 10 sealant manufacturers, including Stans, Orange Seal and Joe’s No Flats, and asked them to answer some key questions about the environmental impact of their products.
Their responses, which are published in full at the bottom of this article, make for insightful reading and threw up a number of interesting questions I hadn’t previously considered.
What is the environmental impact of tubeless sealant?
Most sealants are based on latex or synthetic latex. I was initially interested to find out how latex in both forms degrades when it enters the environment.
I contacted Professor Alistair Boxall, an environmental scientist at the University of York, who has co-authored papers investigating how latex degrades.
Boxall’s research focused on how condoms, which are most commonly made from latex, break down, but he believes the findings of this work would apply equally to liquid sealant.
When latex enters the environment, sunlight begins to break it down. It will first fragment into microparticles before, over time, breaking down to nanoparticles. From this point, the latex will break into increasingly small fragments.
The time it takes for this process to occur depends on environmental conditions, but you can typically expect it to take roughly six to eight months to degrade to nanoparticles.
Boxall also suggested that, as sealant is already in a liquid form, the process would likely be quicker. The process of degradation is the same for both natural and synthetic latex.
Even in super-high concentrations, Boxall’s research found the presence of latex in the environment had no measurable effect on the growth or reproductive behaviours of invertebrates.
All of this chimes with the answers from the brands I contacted.
What about additives in sealant?
Investigating how the latex component of sealant degrades is only part of the story.
All sealants will have some sort of chemical additive included to either aid the sealing of punctures or prolong its useful life.
I didn't ask the brands contacted to list the exact ingredients of their sealant because I already knew few would want to divulge their closely-guarded recipes. However, some brands did give unprompted insight into what goes into their products.
Stan’s says its sealant, which is based on natural latex, uses additives “found in things like shampoo, toothpaste, cosmetics and pharmaceuticals” that have “no known negative environmental effects”.
Finish Line revealed that the liquid component of its sealant is based on a water and propylene glycol mix.
Either way, all of the brands we spoke to claimed that the effects of the liquid element of their sealant entering the environment is negligible.
While no one was likely to say that their product is truly toxic, it appears that, on the whole, the liquid component of most sealants is not harmful to the environment.
Are the particles in tubeless sealant biodegradable?
All sealants have a particulate added to assist in healing punctures
If you flat, these particles are transported by the sealant to collect around the hole.
The force of the air released from the hole compresses both the sealant and particles to form a plug. As the sealant reacts with the air, it cures and the plug forms an air-tight seal, fixing the tyre.
In a time before mass awareness of the impact of microplastics, it was often recommended to add glitter or confetti to sealant to improve sealing performance.
I will admit to having done this once and, while undoubtedly effective, I almost immediately regretted it. The first puncture I got released a small amount of sealant that coated my bike in an obstinate gluey-glittery mess.
At a manufacturer level, there is a lot of variation between what material is used to make these particles.
Finish Line uses “a mixture of Kevlar fibres, post-consumer (recycled) rubber and naturally occurring minerals”. Finish Line says those Kevlar fibres are not biodegradable, but that they are "non-toxic to aquatic life and pose no unusual environmental hazard".
On the other end of the spectrum, Rene Herse/Panaracer uses ground-up walnut shells, which it says are completely biodegradable. Peaty’s also uses an interesting form of biodegradable glitter that is made from “sustainably sourced cellulose from eucalyptus bark”.
Stan’s is widely rumoured to use silica-based crystals (aka, sand) in its sealant but says the particulate blend is a "proprietary trade secret". The "vast majority" is biodegradable, according to Stan's.
"The remainder is made up of natural and sustainable products but can't be termed 'biodegradable', sort of like how one might say rocks aren't biodegradable," the company adds.
While the toxicological hazards of microplastics are still very poorly understood, from an ethical standpoint, introducing pollution – toxic or otherwise – into our environment is a bad thing. It’s our responsibility to dispose of sealant in the correct manner.
Try to avoid what I did – both overfilling a tyre and spilling it in the first place – and always refer to your preferred sealant manufacturer's recommendations when the time comes to retire your tyre milk.
All of the brands I spoke to cautioned against disposing sealant down the drain. Oko and Muc-Off both suggested that dried up sealant should be disposed of with regular dry household waste.
Do you have any eco-friendly recommendations for tubeless sealant additives? I recall black pepper being suggested as a substitute for glitter, but that may have just been a fever dream caused by ammonia inhalation from huffing too many sealant fumes.
Is using a tubeless setup more eco-friendly than inner tubes?
Something I never expected to hear was the suggestion that a tubeless setup is more eco-friendly than a regular tubed setup.
Muc-Off goes as far as to claim that its sealant has been “independently tested and found to be carbon positive” because using it will, typically, make tyres last longer.
Halo makes a similar claim, saying that as “tubeless sealant replaces an inner tube” it is better for the environment because “fewer tubes in usage results in less butyl or natural rubber to be produced in, and transported from, the Far East”.
These claims are extremely difficult to assess – supply chains for these sorts of products are complex.
However, the point about the net-positive reduction in waste due to fewer bicycle inner tubes being sent to landfill is a little dubious, as far as I'm concerned, as long as punctured tubes are reused.
An inner tube is almost infinitely repairable – and you should patch your tubes – so they needn’t be retired in most cases.
Likewise, tubeless tyres must be lined with what is essentially a butyl inner tube to make them airtight, so more rubber is used at the time of manufacturing the tyre.
I would also recommend always riding with at least one spare tube when using a tubeless setup because, should it fail, you will be stranded; so it’s not as if going tubeless makes tubes disappear completely.
Boxall also made the very valid point that, while it may be a natural product, it’s worth remembering that latex is usually grown in massive monoculture rubber tree plantations.
Whether the environmental cost of the production of natural latex is actually greater than that of producing butyl tubes is beyond the scope of this article. I would invite anyone with knowledge in the area of natural and synthetic rubber supply chains to add your thoughts in the comments below.
How can we make tubeless sealant more environmentally friendly?
The obvious starting point is packaging and transport, and both Stan's and Peaty's acknowledge the environmental impact of their products beyond the sealant itself.
"Of course, we're not perfect and the ingredients are delivered by diesel-powered trucks, shipped in plastic bottles, and so on but our New York facility, where all of our sealant is produced, is solar-powered," says Stan's.
If it were possible to package sealant in biodegradable or easily recyclable containers, that could only be a good thing.
If it were possible for sealant to be shipped in a dry powder or undiluted form, which could be mixed by the end-user, this would drastically reduce weight. This would, in turn, reduce the environmental cost of the sealant being shipped.
It’s also possible that, in most cases, the particulates used to aid sealing could be replaced with biodegradable options.
If the walnut shells used in Panaracer’s sealant, or the cellulose-based glitter used in Peaty’s, can be shown to be as effective as other materials (all while being more environmentally friendly than traditional materials) there would be little argument to not adopt them.
Moving to alternative and more sustainable sources of latex, such as dandelions, could also be considered by sealant (and tyre) manufacturers.
Lastly, ensuring that we all responsibly dispose of sealant will also, of course, help. Not all responsibility can be lumped onto manufacturers.
This usually involves mopping it up with paper towels and disposing of it with regular waste, rather than washing it down the drain, but double-check with your sealant manufacturer to be sure.
What is the environmental impact of tubeless sealant? Answers from 10 key brands
The full answers from each brand I contacted can be found below. It makes for really interesting reading and, as previously mentioned, threw up a number of points I would never have considered before writing this article.
If you have any further questions you’d like to pose to the brands, let me know in the comments.
[Editor's note: since publishing, Weldite has supplied an answer to questions two and four. We have amended the article to now include these responses]
1. What is the environmental impact of your sealant?
- Finish Line: The product is free of latex and adhesive compounds. All ingredients are non-toxic and the product is “readily” biodegradable.
- Halo: Tubeless sealant replaces an inner tube, making it largely more positive for the environment. Fewer tubes in usage result in less butyl or natural rubber to be produced in, and transported from, the Far East. Our sealant is also made in the UK which has a lower carbon footprint due to being made locally.
- Joe’s No Flats: Short answer: very low.Full answer: compared to all the other parts of your bicycle, the sealant probably has the lowest impact on the environment. The process of manufacturing the sealant requires a minimal amount of energy as there are no heating or other energy-intensive manufacturing steps. In addition, there are no by-products or waste and the raw materials are mostly from natural sources and biodegradable.
- Muc-Off: No Puncture Hassle sealant makes the tyre last longer and therefore reduces the negative environmental impact. We are proud to say that No Puncture Hassle has been independently tested and found to be carbon positive because of the way that it makes tyres last longer in terms of sealing punctures and conditioning the tyres. Tyres have a significantly worse negative impact on the environment.
- Oko: All OKO sealants are designed to be safe in use, are hazard-free, and they meet the latest international chemical safety standards (whereas natural latex tubes or sealant products should carry hazard pictograms because they can be dangerous to people with specific allergies).
- Orange Seal: There are natural and synthetic rubber latex structures. We utilize natural rubber latex that is produced by plant species. The process of rubber degradation has been studied for years and is very complicated and continues to challenge researchers, hence there is no absolute statement on latex degradation.Natural rubber is formulated in many ways by producers around the world – one raw material for many industries: tyres, tubes, paint, condoms, gloves, balloons, caulks and sealants, to name a few. There are many methods to stabilize natural occurring latex and these stabilization methods can prevent or slow the biodegradation process.We source our naturally-occurring rubber latex from reliable sources that have the least impact on the molecular structure of natural rubber latex.Degradation – we need specific fungi and bacteria from mother earth. If you’re out on the road or trail system, and our sealant hits the ground it will vulcanize rapidly, and then we begin the process of long term biodegradation as we wait on Mother Nature to deliver specific bacteria and fungi to help break down the natural rubber latex.
- Peaty’s: It's very light. We use a water-based synthetic latex formulation. Water-soluble sealants are much better for the environment than those that are suspended in ammonia or other aggressive solvents. Ammonia will damage skin, eyes, rubbers and even carbon and metals. It's very volatile and is often associated with death or injury in industry just by a brief inhalation of ammonia gas (i.e. Carlsberg plant accident 2016). We manufacture and bottle in the UK so this gives us a much lower carbon footprint than any imported products. Some sealants on the market use natural latex which is a big worry as large tracts of natural forest habitats are being destroyed for rubber plantations. I'm [Tom Makin] an Environmental and Microbiological Scientist by trade and have seen the devastation this causes first hand working at orangutan conservation projects in Borneo. The final important thing here is the packaging. We promote the reuse of our packaging and encourage shops and individuals to refill and recycle to minimise single-use plastics.
- Rene Herse: The sealant itself is made from natural materials, and the environmental impact is very small. The biggest impact comes from the plastic bottle – it's made from polyethene – the same material used for bottled water bottles.
- Stan’s: Speaking strictly to the contents of the bottle there is little to no environmental impact. Several of the key ingredients are food grade and found in things like shampoo, toothpaste, cosmetics and pharmaceuticals, and have no known negative environmental effects. We also use natural latex rather than a synthetic variety. Of course, we're not perfect and the ingredients are delivered by diesel-powered trucks, shipped in plastic bottles, and so on but our New York facility, where all of our sealant is produced, is solar-powered.
- Weldtite: Weldtite Tubeless sealant is water-based but does use a synthetic latex which is non-hazardous (therefore no health warning symbols). Besides the obvious advantages of using synthetic latex, e.g. no allergy concerns, there are performance benefits too; sealant dries out much more slowly, it is wheel and tyre friendly, it doesn’t clog up and it doesn’t give off the ammonia smell latex sealants do.
2. How does your sealant degrade and how long does it take to degrade?
- Finish Line: As a readily biodegradable product, once exposed to typical conditions in the open environment, there will be greater than 80% degradation in 28 days.
- Halo: There is no shelf life in the bottle if properly stored, so there is no wastage or degradation. In the tyre it dries out in up to 6 months, depending on the climate. It can be easily removed and mixed in with dry domestic waste. If it is still fresh and liquid in the tyre when that is shredded, then we recommend you carefully pour it into a container and mix with new sealant in the new tyre.
- Joe’s No Flats: We use natural rubber (latex) and water in our sealants. Natural rubber is extracted from the Hevea Brasiliense tree (without harming the tree, of course) and once the sealant is used and dries up, natural decomposition of the rubber takes place. The biodegradable process speed varies depending on factors such as exposure to UV radiation, moisture, soil bacteria, temperature and other environmental factors, but it always ends where it started – natural elements.
- Muc-Off: Like all tubeless sealants – but slower than others – No Puncture Hassle can dry out after 6+ months in temperate climates. Unlike others, it is easy to peel off the dried sealant from the inside of the tyre and dispose of it responsibly as solid waste.
- Oko: It is impossible to quote a definite timescale. If you were to squirt any sealant out on the ground by accident, it would soon dry out. Ours would not cause any adverse effect to the environment.
- Orange Seal: We at Orange Seal minimize the additive materials that work in conjunction with our natural rubber latex to create a strong solution for plugging larger holes. With our minimal approach, our “biodegradable” lifespan is shorter than other consumer latex-based products and a lot better than the plastic in the landfills and on roadsides. We are very conscious of the impact to Mother Earth and have zero waste of liquid latex in our manufacturing process – sealant never sees a water ecosystem in our manufacturing process.
- Peaty’s – It's very hard to be specific on this one as it completely depends on the environment the sealant is in such as temperature, moisture and which organisms are present which can break the sealant down. For example, it's the same principle if you leave some food in a warm damp environment it will degrade much quicker than in a cold or hot dry environment.
- Rene Herse: The sealant seals the tires by solidifying in contact with oxygen. That is also how it biodegrades. How this takes depends on how much oxygen is present.
- Stans: The natural latex that we use as well as the other key ingredients are biodegradable through exposure to normal sunlight and other weathering processes. The time needed to degrade will vary but while shelf-stable, some of the ingredients have a half-life of less than eight hours with exposure to air and sunlight. Natural latex breaks down to more simple elements significantly more quickly than synthetic latex, which is derived from petroleum products.
- Weldtite: This is difficult to quantify and depends entirely on the conditions present at the time the sealant is introduced to the environment. Weldtite sealant won’t harm the environment and will dry out quickly once outside of the tyre.
3. What happens if your sealant enters a watercourse?
- Finish Line: We would expect no negative consequences.
- Halo: Ideally that is to be avoided if possible. Our sealant is non-toxic and with only a few millilitres of product in each tyre, it will be very diluted and should not cause any ill effect. The ideal situation is that any potential hole is sealed instantly and any larger volume of sealant does not escape the tyre.
- Joe’s No Flats: If our sealant enters a watercourse it gets diluted, breaking the formulation components’ balance. The rubber will decompose in the water. In fact, with the rubber we use, decomposition accelerates in water.
- Muc-Off – Even as an undiluted sealant, it is classified as ‘non-hazardous’ and poses no danger to aquatic life. In actual use, if a small amount of sealant leaks into a stream it will be so minute that has no adverse effect.
- Oko: This would be unfortunate but not significant. Even in its original 100% form, OKO Magic Milk is not dangerous. Some other sealants use large amounts of ethylene glycol, in proportions that make them an environmental hazard to fish.
- Orange Seal: If our sealant hits a water stream it will dilute and hopefully make the molecules for biodegradation smaller, but there are no scientific tests (that we are aware of) in the labs or ecosystems of today that can replicate the supply of naturally occurring bacteria and fungi in conjunction with running water for biodegradation of latex solutions.
- Peaty’s: Our sealant is water-soluble so it disperses quickly with very little effect. Knowing that sealant will find its way into the environment at some point, from the very start we distanced ourselves from the traditional micro-fibres, micro-beads, microplastics, 'rubber crumb' (ground-up tyres) and aluminium filings that other sealants use and gone with a completely biodegradable glitter platelet. It’s made from sustainably sourced cellulose from eucalyptus bark, which the tree sheds naturally anyway and degrades quickly in the environment.
- Rene Herse: Not much. If it's a creek, there will be oxygen present, and the latex will solidify and biodegrade.
- Stans: In the volumes used by consumers and workshops and with the concentrations of each ingredient involved, exposure to water sources is not a concern. In large, industrial quantities the individual ingredients could pose a risk to fish, for example, by depleting the oxygen in the water. That is only a concern for the manufacturing facilities producing the ingredients and when we receive tanker truck deliveries.
- Weldtite: Whilst the sealant will degrade and dissolves slowly in water, we would always recommend against disposing of in drains.
4. What particulate do you use to aid sealing in your sealant? Is it biodegradable?
- Finish Line: Our product uses a small amount of Kevlar fibres which are not biodegradable. These fibres are, however, non-toxic to aquatic life and pose no unusual environmental hazard.
- Halo: Our specific fibres and sealing agents are a trade secret. They are not all biodegradable but we are working on increasing this aspect for the future. What we can confirm is that our fibres and sealing agents are made from mostly recycled materials and are not microbeads.
- Joe’s No Flats: Small particles and fibres we use vary between our sealant portfolio. In general, these particles and fibres are biodegradable. Those that are not biodegradable are inert recycled materials. We also use biodegradable antifreeze in our sealants.
- Muc-Off: The fibres present in No Puncture Hassle are aramid fibres (recycled tyre product). They help to seal the larger holes and intertwine to form a permanent, high strength seal. We use biodegradable ingredients in the liquid element of the product.
- Oko: As the name suggests, Magic Milk Hi-Fibre race sealant uses specific extra fibres compared to those in our standard MTB product Magic Milk Tubeless – we have adopted these following years of testing before we introduced the product at Eurobike 2018. They are not biodegradable but users can responsibly dispose of surplus sealant. Any liquid or solid used OKO sealant can be mixed with absorbent material and put in household waste.
- Orange Seal: We feel it is important to understand the definition of biodegradable – all the elements in a compound must be able to naturally breakdown into their original raw ecosystem state. An example is a leaf, when it is done with photosynthesis it falls off and naturally decays back into dirt due to the bacteria and other organisms of mother earth. Other examples of biodegradable materials: Human and animal waste, plant products, wood, paper, food waste. Water is in its naturally occurring raw state, therefore, it cannot degrade. Most sealants have a large part of water therefore they technically cannot be biodegradable. We are environmentally friendly and do not add caustic ingredients back to the earth just vulcanized rubber which in turn can be broken down over time with the right bacteria and fungi. Therefore we cannot label our product as biodegradable.
- Peaty’s: We have used our biodegradable glitter particulate made from sustainably-sourced hardwood cellulose from the start. It's completely biodegradable! It's hard to believe that other companies are still getting away with using micro-plastics and rubber crumb while still claiming their products are biodegradable! Micro-plastics are already a big issue for us and resistance is growing substantially for their use. We have always wanted to lead from the front on this one and hope the other brands will follow.
- Rene Herse: The main ingredients are water, latex and walnut shells. All ingredients are biodegradable.
- Stans: The particulate blend we use – our "sealing crystals" – are a proprietary trade secret but we can say the vast majority is biodegradable. The remainder is made up of natural and sustainable products but can't be termed "biodegradable", sort of like how one might say rocks aren't biodegradable.
- Weldtite: The main ingredients in Weldtite Tubeless Sealant are biodegradable and will not harm the environment.
Thank you to Alistair Boxall for his advice and time, and to all of the brands who agreed to contribute to the article.
