I love it when the kids play outside on the trampoline in the yard. It’s great having them play close to home where I can see and hear them, and it’s great knowing that they’re getting good cardio exercise that’s building their strength. It’s not so great when they tramp their black feet from the trampoline through the house after.
In general, your feet turn black from one of two main causes, either carbon as the polypropylene trampoline mat itself breaks down in the sun (dangerous), or the dirt and grime that has built up from the atmosphere and environment (needs a good clean).
Let’s go through and look at both of these in more depth, including what causes each, why is it a problem, and what we can do to fix it.
Why Do Your Feet Turn Black On A Trampoline, And What To Do About It?
I pulled together a summary table that shows what the two main causes of black feet on a trampoline.
| Source of “Black” | Dirt & Grime | Carbon |
| Caused By : | Atmosphere | Trampoline mat breaking down in UV-rays |
| What does it mean? | Surface dirt | Mat is losing strength |
| How to fix? | Wash mat with soap and water | Mat needs to be replaced |
As you can see, the middle column shows that one of the main causes of having black feet from a trampoline is pure dirt and grime. This broadly comes from the atmospheric pollution, as well as body oils and sometimes dirt from the kids themselves. To stop it from happening, it will need to be cleaned off the trampoline with soapy water.
The right-hand column shows the other main cause of having black feet on a trampoline is the trampoline mat itself breaking down in the sunlight. Black trampoline mats are designed to withstand the outdoors, but eventually break down as they reach the end of their useful life, releasing carbon in the process. To stop it from happening, unfortunately, it’s new trampoline mat time. Once this process starts, it’s not reversible.
We’ll start with the easier one, the dirt and grime from the atmosphere, and then move onto the more complex one about the carbon from the mat breaking down.
1. Feet Turn Black from a Dirty Grimy Trampoline
Why Do Trampolines Get Dirty and Grimy?
Everything gets a bit grimy over time, you just have to look at an old building just after it has been cleaned and restored to see how much grime from the ages builds up.
Trampolines get dirty and grimy as the dirty from a combination of grime in the air, as well as whatever yard dirt the kids bring onto the trampoline, and of course, their body oils and sweat.
With the mat being a horizontal surface, trampoline mats just have more stuff landing on them.
From The Atmosphere
Our atmosphere is filled with tiny particles. These particles come from the breakdown of asphalt or tarmac roads as cars and trucks drive over them. Some of these dry out, along with the rubber from tires, and end up floating through the air. Eventually these land as tiny sticky bits of grime.
Other particles come from the breakdown of nature around us, including dusty dirt, dried out dead insects, and mud, leaves, pollen and flowers. These also float through the air until they land somewhere and stick.
Finally, soot and ash from fires, as well as particulate gases from manufacturing plants, can also deposit sticky chemicals over the mat.
From The Kids
As kids step from the ground onto the trampoline, they bring tiny (and not so tiny) bits of dirt and grass from the ground. These then cling to the sticky particles from the air pollution mentioned above.
The kids will also leave their body oils and sweat on the trampoline. As they bounce on their feet and do tricks which land them every which way, small amounts of body oils are deposited on the trampoline as well.
One watchout: Don’t get the kids to wear socks instead of bare feet to avoid this. If you are in a dry climate or it’s winter, wearing socks on a trampoline will build up static electricity, and they’ll get a static shock when they touch you or the frame.
How To Tell If You Have Grime On Your Trampoline
All of these together make up the slightly oily dirt that is grime.
You can tell you have it by using a fingernail to scrape across the top of your black trampoline mat. Put some pressure on your finger as you pull your nail toward you.
If there is a buildup of black stuff under your fingernail, that feels a bit sticky to touch, then your trampoline has just gotten a bit dirty over time.
If you just rub the pad of your finger over the top of the mat, it is unlikely that your finger will get dirty from grime.
How To Get Rid Of The Layer Of Grime On A Trampoline
Fortunately, cleaning off the layer grime on a trampoline is fairly straightforward.
Black trampoline mats are generally made of polypropylene, which is the same material that a kitchen spatula is made of. Think about what you can do with a spatula, in terms of the washing it in the dishwasher or sink, and it’s pretty similar for a trampoline mat.
I’d recommend starting with either a pressure washer, or a bucket of hot soapy water and a bristle brush.
You can pressure wash a trampoline mat, as I have an email of confirmation directly from a manufacturer. I wrote a longer article about pressure washing a trampoline to get rid of algae and moss here, and the principle is the same.
You can also use a bucket of hot soapy water. The heat helps the oils in the grime melt a bit, making it easier for the soap to dissolve them. By using a bristle brush, not a wire brush, you can give some mechanical agitation (otherwise known as elbow grease) to getting the grime out of all of the woven plastic.
Be sure to rinse off all of the soap before the kids get back on. It can be a bit slippery otherwise.
2. Feet Turn Black From Carbon When the Mat Breaks Down
What are Trampoline Mats Made Of?
In general, black trampoline mats are made of polypropylene. The better quality mats are made from a plastic that is given a brand name Permatron, made by TenCate.
Permatron consists of polypropylene mixed with carbon black fibers. This material doesn’t stretch, which is ideal as it allows the springs to do the work, and it’s so strong it’s also used as a hurricane barrier. It’s also mold- and moisture-resistant. Permatron has excellent UV protection.
This addition of Carbon Black to give UV-protection extends the life of the trampoline mat from around 6 months (cheaper fabrics) in the sun to up to 10 years. You can see what the life expectancy is meant to be from the manufacturer’s warranty.
Why Is Carbon Released From A Trampoline Mat
Even the greatest plastics will break down in the sun, and trampoline mats are no different.
When the UV-light hits the trampoline mat, usually, it does no damage as the UV light is absorbed by the Carbon Black.
Over time however, just enough of the UV light hits the polypropylene fibers.
This excites the photons in the plastic fibers. This then reacts with oxygen in the atmosphere. Next, carbonyl groups in the main chain are produced and the areas of the component which are exposed could then be prone to cracking or discoloration.
This cracking then releases the carbon from the trampoline mat, which can get on your feet and clothes, turning them black.
What Does It Mean When Carbon Is Released From A Trampoline Mat?
When your feet start to turn black from the carbon means the plastic in the trampoline mat is cracking. Unfortunately, this means the trampoline is reaching the end of its useful life. No amount of cleaning will improve the structural integrity of the trampoline. In fact, cleaning off the Carbon Black will just increase the amount of UV rays getting to the polypropylene fibers.
Before the mat breaks completely whilst someone is jumping on it, I would recommend getting a new mat as a matter of some urgency.
How To Tell If Your Trampoline Is Breaking Down and Releasing Carbon?
When you rub your hand over the trampoline, a slight layer of black powder will come away on your hand.
If you do the fingernail test we used for grime, you’ll get black under your fingernail, but it will be a darker black (if that’s possible!), and will be more powdery than sticky.
What To Do When A Trampoline Mat Breaks Down?
When the trampoline is releasing carbon black, it’s now time to replace the mat. There’s unfortunately no fix for this, as it is the actual plastic in the trampoline mat that is breaking down.
As it gets weaker, your trampoline mat is more likely to rip and tear.
In Summary
When your feet start to turn black from the trampoline, it’s either because the trampoline has a build-up of dirt and grime, or because the trampoline mat itself is breaking down and releasing carbon black.
