How to Tell 201 from 304 Stainless Steel Locker — 5-Second Quick Test Without Tools

Canvas Test — Can You Tell Them Apart?

If you put a 201 locker and a 304 locker side by side, can you tell which is which?

Most buyers say yes. Most are wrong.

They look identical. Same silver shine. Same brushed finish. Same weight in some sizes. Even some suppliers can't tell without testing.

Why does this matter? Because the price difference is 40-50%. If you order 201 but pay for 304, you lose money. If you order 304 but get 201, your locker might start rusting in 18 months.

Here's how to tell them apart. No tools needed for the first test.

Method #1: The Magnet Test (Free, Takes 5 Seconds)

How to do it: Take a small magnet (a fridge magnet works) and stick it to the locker surface.

What happens:

• 201 stainless steel is slightly magnetic — the magnet will hold weakly

• 304 stainless steel is non-magnetic — the magnet won't hold

Why this works: 201 has higher manganese content and a different crystal structure. This makes it slightly magnetic. 304's austenitic structure makes it nearly non-magnetic.

Warning — this test is not 100% reliable:

• Some 201 grades are also non-magnetic

• Cold-rolled 304 can become slightly magnetic (the rolling process changes the crystal structure)

• A magnetic test only gives you a hint, not a guarantee

Use this as a quick initial check. Never rely on it alone.

Method #2: The Stainless Steel Test Solution ($10, Takes 30 Seconds)

What you need: A bottle of PM stainless steel test solution. Costs about $10 on Amazon or Alibaba. One bottle lasts for hundreds of tests.

How to do it:

1. Clean a small spot on the locker surface

2. Scrape lightly to remove the protective layer

3. Drop one drop of test solution

4. Wait 30 seconds

5. Wipe off and check the color

What happens:

• The drop turns red or pink within 15-30 seconds = 201

• The drop stays clear or very light yellow = 304

Why this is the gold standard: The solution contains sulfuric acid and other reagents that react with nickel. 304's higher nickel content (8-10%) resists the acid. 201's lower nickel content (3-5%) can't resist it — the reaction creates a red color.

This is what most inspection companies use. If you're buying from a new supplier, ask for a video test. Most legitimate suppliers will do this on camera without hesitation.

Method #3: The Visual & Weight Check (Quick but Less Reliable)

Look at the finish:

• 304 typically has a cleaner, more uniform brushed finish

• 201 often has slight color variations — a tiny bit more gray or yellowish

But: This depends on the factory's polishing and passivation process. A good 201 finish can look better than a bad 304 finish. Don't judge by looks alone.

Weigh it (for the same model):

• 304 is slightly denser (7.9 g/cm³ vs 7.8 g/cm³)

• For a standard 3-door locker, the difference is about 1-2 kg

But: Different models, door configurations, and back panel thickness affect weight more than the material difference. Only compare identical models from the same production line.

Method #4: Request a Material Test Certificate (MTC)

This is the most reliable method.

What to ask for: A Material Test Certificate (MTC) from the steel mill that produced the raw material. This certifies the exact chemical composition — what percentage of nickel, chromium, manganese, etc.

What a legitimate MTC shows:

• 201: Ni 3.5-5.5%, Cr 16-18%, Mn 5.5-7.5%

• 304: Ni 8-10.5%, Cr 18-20%, Mn <2%

Pro tip: A supplier who provides MTCs without being asked is usually trustworthy. A supplier who hesitates or makes excuses is worth a second look.

Quick Reference Table

What We Do at Our Factory

Every batch of lockers we ship gets a material test before production starts. We use PM test solution on every production batch:

1. Incoming steel coil → tested against the MTC

2. First unit off the line → tested at the weld point

3. Random samples during production → spot-checked

We share these test results with buyers on request. No excuses, no delays.

If we test our own materials in front of you, why wouldn't you test ours?

FAQ

Q: Can you really tell 201 from 304 with a fridge magnet?

It's a quick hint, not a guarantee. 201 is slightly magnetic. 304 is not. But cold-rolled 304 can become slightly magnetic from the rolling process. Don't rely on this alone.

Q: Where can I buy stainless steel test solution?

Amazon, Alibaba, or any lab supply store. Search "PM stainless steel test solution." About $10 per bottle.

Q: Will the test solution damage the locker?

A tiny drop on the surface leaves a mark about 2mm wide. It's barely visible. If you test in a hidden area (inside the door, back panel), nobody will notice.

Q: I tested my locker and it showed 201, but the supplier said it's 304. What do I do?

Ask for the MTC. If they can't provide it, or the MTC doesn't match, you have a case. Most suppliers will replace the units if the material specification is wrong.

Q: Can I inspect during production? I want to see the material test.

Yes. Most suppliers allow video inspection during production. We do. If you're ordering a large quantity (100+ units), an on-site inspection is worth the trip.

Q: What's your MOQ?

Standard models: 10 units minimum. Sample orders welcome — 1 unit for quality check and testing.

Q: Do you provide MTC with every order?

Yes. Standard with every shipment. We source from certified steel mills and can provide the mill's MTC.

Q: Do you ship 201 and 304 in the same order? Can I tell them apart after installation?

Yes, we can split an order. But once installed, you won't be able to tell them apart without testing. We recommend keeping a simple record — which locker areas got 201, which got 304.

Q: Lead time?

15-20 days for standard. 25-30 for custom.

Q: Warranty?

Cabinet body: 1 year. Locks: 6 months.

The Bottom Line

201 and 304 look the same. That's the whole problem.

The magnet test is quick but not reliable. The test solution is cheap and reliable. The MTC is the gold standard.

If a supplier hesitates to test their material in front of you, that's a sign. Most legitimate suppliers will do it on video without being asked.

Questions about material testing? We'll show you the test on camera — before you order. Quotes within 24 hours.