Hey there Diggers!
I want to discuss a topic my cousin brought up at Thanksgiving dinner. I’ve seen this question asked frequently, and the often repeated and incorrect answer drives me nuts.
If you’re a big history buff and you’ve found your way onto an old battlefield or two, this should resonate with you.
And if you’re a firearms enthusiast like my cousin Pete, stick around for this quick science lesson.
But first things first, let me give you the answer that brought you here.
Lead bullets turn white, given enough time and exposure to the appropriate environmental conditions.
Why Do Lead Bullets Turn White?
It’s common to find bullets with a white coating or powdery exterior.
For bullets to eventually turn white, they must be made of pure lead or a lead alloy.
This white stuff found on a bullet is known as a patina, or a level of oxidation built over time.
While you might think this is more likely found on recently discovered old Civil War bullets, it can occur with modern-day ammunition too.
But here’s the popular answer I take issue with.
Everywhere I look, the white patina found on old bullets is chalked up to a case of lead oxide.
Close, but no cigar.
The white lead coating on old bullets is actually the oxidation of lead carbonate.
Am I being picky? Maybe. But there are some clear differences.
I’m no chemist, but a quick online search will tell you that lead oxide comes in many colors. Red, yellow, orange, and black, to name a few. But white isn’t typically mentioned.
However, lead carbonate always presents itself as a white corrosive substance.
How Does Lead Turn White?
The oxidation process that turns lead white, specifically on bullets, is caused by prolonged exposure to moisture and carbon dioxide.
Carbon dioxide is found just about everywhere. It’s in the oceans, in the groundwater, and in our atmosphere.
That’s why this type of oxidation occurs, with buried bullets of the past and those newer forgotten casings on storeroom shelves.
In the past, bullets were made from pure lead unless shortages arose in which other materials were used.
Pure lead is highly susceptible to oxidation, so modern bullets are usually coated with polymer or wax.
But the process of making bullets is a cautious one.
Improperly shaped casing or heavy-handed crimping can easily scrape the coating of a bullet and expose the lead to harmful elements.
How Long Does It Take Lead to Turn White?
Does this happen overnight? Absolutely not.
You can’t put a specific number on how long it takes lead to turn white because of the individual conditions of the bullet. Specifically, the portion of lead purity exposed and the environmental conditions its been subject to.
The rate at which a pure lead bullet with no protective coating turns white will differ from a bullet partially coated sitting right next to each other.
Another thought to consider is the extremities of the environmental conditions.
The more moisture or carbon dioxide affecting a lead bullet, the faster the oxidation process transpires.
If you’re like me, you hate the typical answer of ‘it depends.’
I wish I could be more precise. But I have two facts that might demonstrate just how uncertain it is.
First, ammunition manufacturers will list an expiration date of ten years after a bullet was made.
But this is more of a technicality and for the lawyers’ peace of mind.
A carefully stored bullet will last until it’s exposed to enough humidity and oxygen that the primer begins to degrade.
Second, the rate of carbon dioxide increases constantly. And as I said, the more carbon dioxide exposure, the faster lead carbonate forms on a bullet.
Currently, the percentage of CO2 in the atmosphere is hovering around 0.04%, or 419 parts per million (PPM), as of October 2022.
Doesn’t sound like a lot, does it?
While the PPM trend is rising, the atmospheric fraction it makes up is another reason it takes so long to turn a lead bullet white.
Is White Lead Dangerous?
Before we tackle the danger level of white lead on bullets, let’s define what we’re talking about.
You see, white lead can have two meanings.
The first, more common meaning for white lead is basic lead carbonate (2PbCO3·Pb(OH)2).
This chemical formula is what most people think of when discussing lead paint and lead poisoning.
Of course, basic lead carbonate, widely referred to as white lead, is extremely dangerous. In its most harrowing cases, it can lead to seizures, a coma, and even death.
But that’s not the white lead we are discussing.
The form of white lead, referred to as lead carbonate (PbCO3), is only dangerous when exposure is recurring over a long period.
The effects include blood, kidneys, and nervous system impairment.
But usually, wearing gloves while handling lead bullets that have turned white and washing hands vigorously is all that’s required to keep you from harm.
My last bit of parting advice…
If you do happen to handle an oxidized bullet, ensure you don’t touch any parts of your face before washing up.
While the exposure may not be enough to make you sick, it’s better to be safe than sorry.