4 science tricks to scare up a better Halloween costume

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Halloween is coming, which means the race for the most awesome costume is on. Fortunately, a little science can add some serious fright to your get-up. These tricks only require a little advance preparation, but your friends will remember the result for years to come.

Apply makeup that only appears under ultraviolet LEDs

Want to play Dr. Jekyll and Mr. Hyde? You can paint your skin with glowing scars, creepy eye makeup, and veiny hands… that only appear under ultraviolet light. Add some UV LEDs to your costume, and you’ll be able to turn this makeup on and off with a switch. Alternatively, amp up your vampire look with similar UV-reactive makeup that’s visible under normal light but produces fluorescence in the presence of a blacklight.

To put this look together, you’ll need specially-formulated face paint that reacts to ultraviolet light. Brands like Moon Glow and Midnight Glo specialize in this type of UV-reactive makeup. For hair products that glow, look for gel or dye from Manic Panic.

Once you have your face paint, you’ll need some wearable LEDs. Look for UV-emitting strip lights, sometimes called “blacklight” strips, which are widely available at hardware stores and online. Choose lights that you can cut and that come wired to a connector, preferably a DC receptacle. If you can’t find a strip with a DC power source, get one with a solderless connector, buy a separate DC receptacle at an electric supply store, and connect the two in seconds—no tools required. In the long haul, this setup is not the sturdiest, but you only need it for a night.

For power, you have a couple options. A battery holder with a DC plug can attach directly to your light strip. Or grab a power bank like the one you use to charge your phone, attach it to a USB-to-DC converter, and connect that to your LEDs. However, before you plug in the power bank, check its maximum instantaneous amperage limit, usually found in the user’s manual. Compare that to the overall amperage the LED strip will pull, which you’ll find in the specifications sheet. If the light strip draws more amps than the battery can provide, the power will drain too quickly, potentially destroying the power bank.

Now that you have your materials in hand, use fabric glue or pins to attach the light strip to your clothing. Put on your UV-enabled costume, apply your UV-reactive makeup, and test the range of the lights in total darkness. This should show you how the effect is working and whether you need to tweak the setup.

Use makeup glue to mimic puncture effects

If you’re planning to dress as a zombie, a heavily memed Skyrim guard, or pretty much anything with punctured skin, add a little interactive element to your costume by inserting a few blood-spattered rods, sticks, or arrow shafts into your body, then letting people pull on them. Of course, you’re not really going to stab yourself with pointy objects—but some stage blood and makeup glue will give people the illusion that you did.

A quick warning: If you’re allergic to latex, check the makeup glue ingredients carefully. Many of them use latex, and anaphylactic shock is not a fun costume trick!

First, find a spot on your body where your skin is relatively loose. To test it, lay the stick or rod flat on the surface and pinch two ridges of flesh together around the object.

[Related: A stork impaled by a 30-inch spear flew thousands of miles to make it home]

Once you’ve picked a good spot, apply the makeup glue to that area, put your prop in the middle, and pinch your skin together lightly, just enough to cover the middle of the pin and keep it in place. To ensure that nobody notices you’ve glued your skin together, you might want to fill in the pinched area with a little foundation. Complete the effect with a bit of fake gore.

Pretend to pull a scarf through your neck

Want to really sell your ghost costume? Have somebody grab your tie or scarf, give it a tug, and watch them gape in shock as it seems to slide through your incorporeal neck. What you’re really doing is creating a loose knot that easily pops off (and isn’t visible from the front). For this trick, you’ll need a scarf or tie about 4 or 5 feet long, and some time to practice and really get the hang of the knot.

Here’s how it works: Put the scarf around your neck, take the ends in your hands, and pull gently until the left-hand side hangs longer than the right. Cross your arms, right over left, with your right hand holding the scarf a little higher than your left. Pull your right hand across, forming a u-bend. Wrap the part of your scarf held by your left hand around your neck, over the bend, and follow with your right, gently resting the loop on the back of your neck. This is a little tough to visualize, so check out the video below for more details.

Finally, ask someone to tug on the left-hand end, and the scarf will seem to fall “through” your body. Once you’ve got the knot down, you can re-tie your neck gear and endlessly repeat the performance.

Play undead with no pulse and endless guts

If you’re going to be one of the legion of Halloween zombies, you should give your costume a couple touches that make it stand out.

The first trick just requires a rubber ball. Hide it in your armpit, ask someone to take your pulse from your wrist, and then squeeze the ball. This will temporarily block your radial artery, which delivers pulsing blood to your wrist. Search as they might, your friend won’t detect the tell-tale sign of life.

[Related: How William Harvey discovered blood circulation]

If that’s too subtle, try a new take on the old endless hanky gag. Get some red “silks,” available at magic shops (you can also make your own with bolts of fabric), and knot them together end to end with a simple square knot. Then fold your ties to form a stack and twist them until they fit in something small and portable, like a cardboard tube.

Stick the tube in your shirt, leaving the end sticking out, and ask somebody to play pull-the-intestine. For bonus points, tie something gross, like a rubber heart, to the last tie. This is particularly great if you really ham it up; shriek, make gagging sounds, or hide a handy fake blood capsule so it creates a grotesque mess.

This story has been updated. It was originally published in 2018.