How to Test Platinum With Hydrogen Peroxide

What if I told you there was a non-destructive, safe test that you can do at home to test a piece for being platinum? Sounds like a load, but it’s actually true in this case. Hydrogen peroxide testing is easy, quick, and very accurate.

So, how does it work? Read on and I’ll show you!

Can You Really Identify Platinum With Hydrogen Peroxide?

Yes, testing with hydrogen peroxide is very accurate. It’s also non-destructive and doesn’t require any chemical expertise, all you need to do is watch for the reaction!

Platinum is used as a catalyst for a number of different reactions. A catalyst is a chemical or compound that interacts with a reaction to speed it up, but the compound itself is neither consumed nor changed during the reaction.

The most common use that most people are familiar with is catalytic converters. If you’ve ever lived in a high-crime area you know that these parts are highly sought-after by thieves, and it’s due to the platinum or palladium catalyst they contain.

Platinum’s reaction with the H₂O₂ is pretty simple: it causes rapid decomposition into H₂O and O₂. This causes a rapid formation of bubbles on the surface of the metal, which is stronger with a higher concentration H₂O₂ solution.

This same reaction has its uses in rockets as well, but that’s a whole different rabbit hole that starts with understanding monopropellant rockets.

The reaction is also used to test possible platinum ores in addition to identifying metals that have been processed. It’s a very strong reaction.

The exact chemical properties of platinum that cause it to work as a catalyst are beyond the scope of this article. For now, all you need to remember is that this reaction is catalytic and converts H₂O₂ into water and oxygen gas.

The H202 Test for Platinum

Gather the following items:

Hydrogen Peroxide (2-3% H₂O₂ from a pharmacy works fine)
A glass, jar, or any other liquid container (preferably glass or ceramic)
Your piece of possible platinum

You should use proper PPE when doing any chemical reaction, but considering most of us have scrubbed open cuts with hydrogen peroxide at some point… well, it’s really unnecessary.

Fill the glass to a level that’s higher than your piece of possible platinum. Then… drop your piece in.

Platinum will react immediately upon entering the solution and begin producing bubbles. You may not get anything as dramatic as you see in Youtube videos since they use higher concentration H₂O₂ in many cases, but it should be immediate or within a second or two.

If you think the metal may be silver, I recommend letting the solution sit for a while. It can take some time for silver to react since it’s not as strong of a catalyst as platinum.

Don’t use higher concentration hydrogen peroxide. Seriously, while the 2-3% solution most of us are familiar with is safe enough to use, once you hit 10% or so the stuff gets nasty. I’ve seen 35% concentrations used to demonstrate catalysis this way and I don’t even think there’s a safe way to do that at home for most people.

The only real safety precaution is to not ignite the oxygen. At a 2-3% concentration that basically means not setting the jar on an active stove burner, but it’s still a possible risk in enclosed areas. If you’re worried about it, just do it outdoors.

When you’ve observed the reaction you can simply rinse off the piece. It shouldn’t have any effect on the surface finish of your metal, and none of it is dissolved in the solution. You can then dispose of the H₂O₂ in a normal fashion.

How To Learn Silversmithing On Your Own!

Other Indications and Tests

Platinum isn’t as common as gold and silver, but this test is a good way to differentiate platinum from white gold.

Jewelry markings give another hint, and most of us don’t come across them often. Anything labeled “pt” or “plat” with no other markings is at least 95% platinum. You’ll also occasionally see a stamp that simply says “platinum.”

You can also torch a suspected bit of platinum, so long as it doesn’t contain stones. Platinum should remain the same color and won’t melt easily. Silver melts at 1,640°F and oxidizes black rapidly when heated past a certain point without any precautions. White gold melts at a slightly higher temperature, with 14k melting at 1736°F for nickel alloys and 1968° for palladium-based white gold.

Meanwhile, platinum is just a bit higher at 3,215°F. Platinum work is a specialized skill all its own due to the high temperatures required. Working silver seems cold by comparison.

This sort of testing can be destructive on some materials and shouldn’t be your go-to. Metal identification is best done with acid tests.

You can also test the density of the material if you have a graduated cylinder or another precise way to measure liquid volume. This is another non-destructive way to check the metal of a piece but you need some precise measurements.

Fill the container up to the volume, drop in your piece, mark down how much the water level changed. Then you’ll weigh the piece. The equation for density/specific gravity is just mass divided by volume.

The densities for these materials is:

Platinum – 21.45g/cm³
14k White Gold (Palladium) -16.5g/cm³
14k White Gold(Nickle) – 14.5g/cm³
Fine Silver – 10.49g/cm³
Sterling Silver – 10.36g/cm³

This isn’t possible if there are stones in the piece tested, which will change the calculations. Hydrogen peroxide shouldn’t damage most stones or at least not those valuable enough to set in precious metals.

But the hydrogen peroxide test is simple, safe, and doesn’t require any special expertise.

Can Hydrogen Peroxide Identify Other Metals?

Silver is similar enough to platinum that it also causes rapid degradation of hydrogen peroxide, but it’ll be a slower process than when you add platinum.

Silver will begin to react after a minute or so. Unlike the steady stream of bubbles provided by platinum, you’ll instead see “pearling” on the silver, which is just a bunch of tiny bubbles forming on the surface.

Silver’s reaction is pretty minor overall, and you’re always best off working with an acid test for silver since you’ll also want to know the purity most of the time.