Life Nomadic: How Airport Metal Detectors Work

I’m a bit fanatical about shaving. Most of my possessions are pared down to the bare minimum, but my shaving stuff is the one big exception. I use a Merkur travel safety razor with Merkur platinum coated blades, a Dovo silver tip shaving brush, and Truefitt and Hill shaving cream.

Excessive, I know.

The blades that the razor uses are standard “safety razor” blades. They’re thin pieces of metal with a blade on each side. That sounds like something that the TSA would possibly prohibit, but in fact they don’t. They mention them specifically in their rules.

They prohibit “Razor-Type Blades – such as box cutters, utility knives, razor blades not in a cartridge, but excluding safety razors.”

Clearly, safety razors are permitted. This is consistent with my experience, too. I’m almost invariably selected for further screening. TSA agents see my razor blades and move on.

And somehow I’ve managed to resist any temptation to hijack a plane with them so far.

In New York a few weeks ago, things were different. The TSA agent didn’t like my razor blades. I insisted that the TSA rules permitted the blades. Things got escalated to the supervisor, an icy woman named Gohel.

“I specifically checked the TSA site and saw that these are allowed. Can we please look over the rules together?”

Gohel told me in clear language that the blades would not be allowed on the plane, and that, no, I could not look at the TSA rules with her. No amount of friendly yet firm pleading would change her mind.

The blades were taken.

I anticipated that this might happen, so I came up with a way to pass small metal objects through the metal detector. I doubt any serious weapon could possibly make it through, but it’s great insurance for those worried that poorly trained TSA agents will confiscate items you’re legally permitted to carry on.
Metal detectors work on a simple principle. One of the walls of the arch you walk through sends pulses of radio waves to the other wall which bounces them back. Their return is timed, and if they come back too soon then they’ve hit metal.

However, they don’t pick up every bit of metal. If they did, then people with metal fillings, metal rivets on their jeans, and metal rings would be unnecessarily detained. The sensitivity is always turned down a little bit.

Because the radio pulses are coming from side to side, if a metal item is aimed so that its thinnest profile is facing the walls of the arches, it is less likely to be detected. I keep a spare blade in my wallet, and it has never set off a metal detector.

There’s no way to know exactly how much metal can pass through a metal detector undetected. I’m sure that the higher ups at the TSA have metal detectors calibrated to catch anything big enough to pose a serious threat.

I have successfully passed safety razor blades as well as small pairs of scissors with no problem. The TSA rules clearly allow scissors under 4″, but agents sometimes have problems with those as well.

Trying to get anything seriously dangerous past the metal detectors would be a very bad idea. I’ve been randomly patted down before, and I wouldn’t want to be caught with something that isn’t clearly allowed by the TSA.

But if you’re sick of being subject to poorly trained TSA agents’ whims and opinions, consider keeping your razors and scissors away from them and their metal detectors.