If your boots have a synthetic insole, the ammonia (or cat pee) smell is coming from the interaction of polyurethane and moisture. You should remove your insole, get a new one, and start wearing wool socks instead of cotton or nylon/polyester socks. You should also use cedar shoe trees in your boots when you’re not wearing them.
If your boots smell like cat pee and you have a cat, I hate to break it to you, but that thing is pissing on your boots day and night.
Cats are traitorous animals and they won’t think twice about ruining the things you love.
But if you don’t have a cat, there’s another surprising reason why your boots can start smelling like cat pee.
No, there’s probably not a feral cat breaking into your house and laying waste to your footwear. Though I wouldn’t rule it out of the question—they’re crafty little beasts.
The problem is actually coming from your polyurethane insoles breaking down due to excessive moisture in your boots.
There are a few ways to fix this problem, though you’re going to have to change the way you wear your boots.
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What Makes My Boots Smell Like Cat Pee?
When polyurethane doesn’t fully dry out and has a high moisture level, it starts to break down. As the chemical bonds are broken, ammonia gas is released.
And ammonia smells a lot like when your cat pees on the carpet and it’s left sitting there for a day or two. Nasty.
So, no, you don’t need to take your cat to the nearest pawn shop (yet). You just need to change a few things on your boots and you won’t have to worry about the smell any more.
5 Ways to Stop the Stink for Good
1. Get New Socks
Not every brand uses the specific type of polyurethane that has this issue, but it’s pretty popular in work boots and running shoes.
The best way to avoid trapping moisture in your boots is by getting different socks. Let me guess: you wear either cotton socks, or polyester/nylon socks. Am I right?
If so, you need to switch to wool socks. You might be thinking: doesn’t wool insulate your foot and won’t that make my feet even more sweaty? No.
Merino wool does insulate well, but it’s also the best sweat-wicking material possible for socks. Cotton and synthetics like nylon are much cheaper than wool, and though a lot of brands will call those fabrics sweat-wicking, they don’t do nearly as well as wool.
I did a massive breakdown on the best work socks and my top recommendation is the Camel City Mill Lightweight work sock. They’ve solved my sweaty foot problems and they’re also super durable.
When you’re wearing wool socks, your boots won’t capture as much moisture from your foot, which is the single best way to make sure your boots don’t start smelling like cat pee again.
Made with Ironside Merino wool, these work socks feature compression through the calf which promotes better bloodflow and helps your feet recover after a long day. Plus, because they're Merino wool, they're breathable and completely knock out foot-sweat.
2. Throw Out the Old Insole
You need to get a new insole. If you can’t remove the insole from your boots, well, you’re just going to have to live with smelling like a litter box or you’ll need to get new boots.
In any case, I’ve found that Tread Labs insoles are my favorite work boot insoles and they’ve helped me so much with back and knee pain over the years.
These are easily my favorite work boot insoles---they’ve helped me so much with back and knee pain over the years.
But you can get any brand. The main thing is that you swap out the insoles asap.
3. Use Cedar Shoe Trees
Cedar shoe trees help absorb moisture from your boots when you’re not wearing them, plus cedar oil has antibiotic and antifungal properties.
Not only do they help the leather last a lot longer, but they also keep your boots smelling fresh (beyond the ammonia odors).
These are pretty much the G.O.A.T when it comes to cedar shoe trees. They're sturdily built from USA grown red cedar wood and have a really nice woody smell to them. They also adjust easily unlike cheaper shoe trees, which makes slotting them in and out of your shoes a breeze.
4. Douse Your Boots with Baking Soda
That insole is going to continue smelling, but if you remove the insole and fill the boot with baking soda for 24 hours, you’ll get a lot of the ammonia stink out.
Now, I recommend that you don’t put your cat pee insoles back into your boots. That’s just foolishness. Instead, pop in your new insoles and finally get some peace of mind.
When you’re ready to wear your boots again, just dump out the baking soda and knock your boots together. You don’t need to remove all the baking soda—just the big clumps to avoid discomfort. It’ll keep fighting odors even when you’re wearing your work boots on the job.
5. Use a Boot Dryer (Optional)
A lot of guys I know use a boot dryer just about every day. Most of them could solve their sweaty feet problems by switching to wool socks, but sometimes a boot dryer is necessary if your leather boots are getting soaked through.
I don’t use a boot dryer myself—wool socks and cedar shoe trees are enough for my needs.
But if you really want to get your boots dry every day, investing in a good boot dryer can help reduce the amount of bacteria that’s able to grow overnight.
You Can Keep the Cat
It’s probably not your cat’s fault that your boots smell like a litterbox.
The real problem is coming from the polyurethane in the insole. The best way to avoid the “cat pee” smell from ever coming back is:
- Start wearing wool socks to reduce foot sweat
- Use cedar shoe trees to absorb moisture in the boot when you’re not wearing them
- Replace the old smelly insole with a new one
- Soak up the nasty smells with baking soda
If you use all four of those tricks, you’ll never have to worry about your coworkers calling you “cat pee McGee” again. You’re welcome.
FAQs
How do I get the ammonia smell out of my boots?
Replace your insole with a new one and fill your boots with baking soda for 24 hours. To avoid the smell coming back, start wearing wool socks instead of cotton or polyester, and start putting cedar shoe trees into your boots when you’re not wearing them.
Why would shoes smell like cat pee?
Some insoles have a specific type of polyurethane which, when exposed to excessive moisture, can start to break down and release ammonia gas. This gives the shoe a cat pee smell that’s difficult to get out if you’re not sure what’s causing the problem.
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