Hey everyone, it’s Jake here from your go-to tin cans supplier. Last week, I got a random DM from a customer—said they ordered two batches of our standard food tin cans, and half the cans stuck to their warehouse forklift magnets, the other half didn’t. They were low-key panicking, thought we messed up materials or something. That made me think: this is a question so many people have, but no one really breaks it down simply, right? So today we’re talking about why some tin cans are magnetic and others aren’t. Let’s cut the jargon and keep this real. Tin Cans
First off, let’s get one thing straight: not all tin cans are actually made of “tin.” I know, that’s confusing. Back in the day, like a hundred years ago, most food tins were thin sheets of actual tin metal. Tin is non-ferromagnetic, so those old cans wouldn’t stick to a magnet at all. But modern food cans? They’re almost always made of steel, with a super thin coating of tin. That coating is just there to stop the steel from rusting and keep food safe, it’s not structural. So when someone asks if a tin can is magnetic, they’re basically testing the steel underneath that thin tin layer. Wait, but why are some steel tins magnetic and others not? Good question—let’s dive into steel types.
Steel is an alloy of iron and carbon, right? But there are so many other elements mixed in depending on what it’s used for. The key here is ferromagnetism—why some metals stick to magnets. Ferromagnetism only happens when a metal has “unpaired electrons” that align in little regions called domains. When those domains line up in the same direction, the whole metal becomes magnetic. Iron is naturally ferromagnetic, but add other elements to make steel, and that changes things.
Most tin cans we supply are made of low-carbon steel, also called mild steel. That’s the stuff that’s cheap, easy to form into those round can shapes, weld together, and perfect for food packaging. Low-carbon steel is super magnetic. But why would a can not be magnetic then? Oh right—some manufacturers use a different type of steel for cans, usually stainless steel. Wait, not all stainless steel is non-magnetic, but the kind used for cans usually is. Let’s clarify that.
Stainless steel is made of iron, carbon, and at least 10.5% chromium, plus other elements like nickel sometimes. The mix of chromium and nickel changes the crystal structure of the steel, which messes with those magnetic domains. There are different grades of stainless steel: ferritic and martensitic stainless steel are magnetic, but austenitic stainless steel—this is the one most commonly used for food cans, specialty containers, and even kitchen appliances—isn’t. That’s why you’ll see those fancy stainless steel water bottles that don’t stick to your fridge magnet.
But here’s the plot twist that confuses people even more: sometimes stainless steel cans will stick to a magnet anyway. That’s not a defect, that’s just how metal works. When you bend, stamp, or form stainless steel into a can shape (which is all we do at our factory, basically stamping those steel sheets into cylinders and crimping the ends), you cause something called “work hardening.” That deformation rearranges the crystal structure just enough to make austenitic stainless steel temporarily magnetic. It’s not a bad can, it’s just a side effect of shaping it. If you heat that can up to really high temperatures (like 1700°F or so), it’ll lose that temporary magnetism again. Most home or warehouse situations never get that hot, so that temporary magnetism stays. So when a customer says half their stainless steel cans are magnetic, that’s almost always why.
Wait, let’s tie this back to my own tin cans, since that’s what we sell. We offer two main types of tin cans: regular food-grade mild steel tins, and specialty austenitic stainless steel tins. The mild steel ones are always magnetic—every single time. They’re cheaper, great for things like soup, beans, pet food, the stuff most people stock up on. The stainless steel ones are non-magnetic when they come off the line, but if you bend them, stamp them, or stack them a certain way (which happens in shipping, warehouse storage, even on the store shelf), some of them might pick up a little temporary magnetism. It’s not a flaw, it’s just the nature of forming metal into a can. I always tell customers who get that to not panic—it’s still 100% food-safe, works exactly like it’s supposed to, the magnetism doesn’t affect the can’s performance at all.
Another thing people ask: does the tin coating have anything to do with it? Nope, like I said earlier, the tin is only 0.00015 inches thick—super thin, that’s about a hundred times thinner than a human hair. Tin itself is non-magnetic, so if the underlying steel is magnetic, the thin tin layer doesn’t change that. If the steel is non-magnetic, the tin layer also won’t make it magnetic. I’ve tested this a hundred times—take a mild steel can, sand off the tiny tin coating with some sandpaper, it still sticks. Take a stainless steel can, sand off the tin, it still doesn’t (unless it’s got that work hardening from being shaped). So the tin is just a protective layer, not a factor in magnetism.
Let’s also bust a common myth I hear all the time: if a tin can is magnetic, it’s not food-safe. That’s totally wrong. The magnetism has nothing to do with whether the can meets food-grade standards. Our mild steel cans go through the exact same testing as our stainless steel ones—we test for lead, BPA, corrosion, all that stuff required by the FDA (and other regulatory bodies around the world). The magnet is just a cheap way to test what kind of steel you’re dealing with, not a test for food safety. I had a customer last year who refused to buy our mild steel cans because a magnet stuck, thinking they were toxic. We sent them samples of both types, did a quick test for them, and they ended up reordering twice as much because the mild steel cans are cheaper and perfect for their product.
So let’s recap, super simple, no fancy science terms:
- Regular tin cans (the kind for soup, beans, pet food) are magnetic because they’re made of mild steel, a cheap, easy-to-form metal that’s naturally magnetic.
- Some specialty tin cans (stainless steel ones) are non-magnetic, usually because they’re made of a specific type of stainless steel called austenitic.
- Sometimes stainless steel cans will stick to a magnet temporarily, just because we shape them into cans— that’s work hardening, not a defect.
- The thin tin coating on all cans doesn’t affect magnetism at all.
- Magnetism doesn’t mean a can is broken or not food-safe.
Now, why does this matter for you? If you’re a restaurant owner buying bulk cans to prep food, a small business owner making craft goods (like candles or homemade jam) that use tin cans, a warehouse manager storing canned goods, or even a crafter using cans for DIY projects, knowing this helps you pick the right can for your needs. If you need cans that won’t stick to magnets (like for a display rack that uses magnets, or for a project where magnetic cans would get in the way), go for our austenitic stainless steel cans. If you don’t care about magnetism, want a cheaper option that’s perfect for bulk food storage, our mild steel cans are the way to go. And if you do get a batch of stainless steel cans that have a little temporary magnetism, just wipe them down or stack them gently—they’ll lose most of it over time, or it’s never going to affect what you use them for.
I get that when something doesn’t work the way you expect, it’s frustrating. Our team here knows that, which is why we always include a little info sheet with every order explaining this whole magnetism thing, just in case someone notices and panics. We’ve had customers tell us that sheet saved them from returning a whole pallet of cans, which is why we make a point to be transparent about this stuff.
If you’re shopping for tin cans, whether you’re ordering 100 for a small business or 100,000 for a large operation, we’ve got you covered. We make all sizes: 4oz sample cans, 12oz standard food cans, 1-gallon large cans, whatever you need. We test every batch to make sure they meet all safety standards, and our team is always here to answer questions—whether it’s about magnetism, coating types, printing options, whatever.
If you’re tired of dealing with unreliable tin can suppliers, hit us up to talk about your needs. We’ll send you free samples, help you figure out exactly which can is right for your product, and give you a fair price that doesn’t cut corners on quality. Don’t waste time with suppliers who don’t explain the basics, and definitely don’t stress if you notice your cans sticking to a magnet—now you know it’s totally normal, and not a red flag.
Thanks for sticking around to read this, guys. Next time you grab a can from the pantry and test it with a magnet, you’ll know exactly why it sticks (or doesn’t). If you have more questions, drop a comment below or reach out—happy to help. Now go stock up on whatever you need, and remember: magnetic or not, our tin cans get the job done right.
Combination Machine References
- Metals, Minerals & Materials Society. Ferromagnetism in Alloyed Steels.
- International Stainless Steel Forum. Austenitic Stainless Steel Properties.
- U.S. Food and Drug Administration. Food Contact Substances: Metal Packaging.
Xiamen Uniteam Sourcing Co., Ltd.
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