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How Does Scratch and Sniff Work?

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Scratch and sniff was born of the noble endeavor of making copies. In the dark ages before word processors, inkjet printers, and the Xerox machine, copies of documents were made by placing carbon paper between the sheet you were typing on and the sheet that would become the copy. In the early 1960s, an organic chemist at 3M named Gale Matson developed a way to make ink copies without carbon paper, using a process called microencapsulation.

The Matson process uses two sheets of paper "“ one for the original document and one for the copy "“ on top of one another. The top sheet of paper is coated with microcapsules of colorless ink. When someone writes or types on the paper, the capsules break and release their ink, which mixes with a developer chemical on the second sheet to create a copy.

Not wanting Matson's technology to be a one trick pony, 3M began to search for alternate uses for micro-encapsulation and found that it could be applied to scented oils as well as ink. Scratch 'N Sniff debuted in 1965 and is found in various forms, from stickers to pull-apart perfume sample strips and beyond.

How It Works

1. Scented oil is mixed with a solution of water and water-soluble (capable of being dissolved in water) polymer (3M uses polyoxymethylene urea) in a large vat called a reactor.

2. The mixture is blended at a high speed by a rotary blade. As the oil and polymer solution mix, the oil breaks into very small droplets. After about 12 hours of blending, the droplets are about 20 to 30 microns in size, invisible to the naked eye.

3. When the droplets are the right size, the blending is stopped and a chemical catalyst is added. The catalyst causes the molecular weight of the polymer to increase and become water insoluble. The polymer precipitates out of the water and forms a shell around, or encapsulates, each individual droplet of oil.

4. The reactor is stopped, and the microcapsules are collected and washed to remove any unreacted or unencapsulated materials.

5. The capsules are placed in a tank and mixed with a water base and an adhesive, forming a thick slurry.

6. The slurry is ready to be applied to paper, and there are four basic methods for doing this: silk-screening, web offset printing, flexo-graphic printing (this is what is used for scratch and sniff stickers) and extrusion (a fairly complex printing method used for making perfume and cologne sample strips).

Smelling the finished product is just like smelling anything else. When we scratch the surface of the paper, the microcapsules break and the scented oil travels to our nasal cavity, where the molecules are detected by the olfactory sensory neurons in the olfactory epithelium. A signal is sent to the brain, which translates it, and then we say, "Oooh, banana!"

Click & Sniff

We've come a long way since the birth of Scratch 'N Sniff, and now we don't need micro-encapsulation to smell exotic scents whenever we want. Heck, we don't even need to scratch. Here are some more recent developments in digital scent technology.

DigiScents Inc. in Oakland, California, created the iSmell scent synthesizer. You insert a scent cartridge into the iSmell, which is connected to a computer or video game console, and it releases the scent in short bursts at appropriate times, i.e. when you're playing a first person shooter and get into a firefight, you'll actually get whiffs of gunpowder as you fire rounds. Before you get too excited, PC World named the iSmell one of the 25 Worst Tech Products of All-Time.
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ScenTeck Technologies' Scratch-N-Sniff Pro software and System Scent Card replace the standard vibrating sound waves coming from computer speakers with unique vibrating tones that the brain recognizes not as a sound, but a scent.
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Unleashed, an album by Savannah, Georgia-based musician Zan, is the world's first scent-enabled CD. A gadget called a Scent-Dome plugged into your computer reads code embedded in the CD and releases different scents as the songs play.

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Big Questions
Why Do Cats Freak Out After Pooping?
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Cats often exhibit some very peculiar behavior, from getting into deadly combat situations with their own tail to pouncing on unsuspecting humans. Among their most curious habits: running from their litter box like a greyhound after moving their bowels. Are they running from their own fecal matter? Has waste elimination prompted a sense of euphoria?

Experts—if anyone is said to qualify as an expert in post-poop moods—aren’t exactly sure, but they’ve presented a number of entertaining theories. From a biological standpoint, some animal behaviorists suspect that a cat bolting after a deposit might stem from fears that a predator could track them based on the smell of their waste. But researchers are quick to note that they haven’t observed cats run from their BMs in the wild.

Biology also has a little bit to do with another theory, which postulates that cats used to getting their rear ends licked by their mother after defecating as kittens are showing off their independence by sprinting away, their butts having taken on self-cleaning properties in adulthood.

Not convinced? You might find another idea more plausible: Both humans and cats have a vagus nerve running from their brain stem. In both species, the nerve can be stimulated by defecation, leading to a pleasurable sensation and what some have labeled “poo-phoria,” or post-poop elation. In running, the cat may simply be working off excess energy brought on by stimulation of the nerve.

Less interesting is the notion that notoriously hygienic cats may simply want to shake off excess litter or fecal matter by running a 100-meter dash, or that a digestive problem has led to some discomfort they’re attempting to flee from. The fact is, so little research has been done in the field of pooping cat mania that there’s no universally accepted answer. Like so much of what makes cats tick, a definitive motivation will have to remain a mystery.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
Why Do Baseball Managers Wear Uniforms?
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Basketball and hockey coaches wear business suits on the sidelines. Football coaches wear team-branded shirts and jackets and often ill-fitting pleated khakis. Why are baseball managers the only guys who wear the same outfit as their players?

According to John Thorn, the official historian of Major League Baseball since 2011, it goes back to the earliest days of the game. Back then, the person known as the manager was the business manager: the guy who kept the books in order and the road trips on schedule. Meanwhile, the guy we call the manager today, the one who arranges the roster and decides when to pull a pitcher, was known as the captain. In addition to managing the team on the field, he was usually also on the team as a player. For many years, the “manager” wore a player’s uniform simply because he was a player. There were also a few captains who didn’t play for the team and stuck to making decisions in the dugout, and they usually wore suits.

With the passing of time, it became less common for the captain to play, and on most teams they took on strictly managerial roles. Instead of suits proliferating throughout America’s dugouts, though, non-playing captains largely hung on to the tradition of wearing a player's uniform. By the early to mid 20th century, wearing the uniform was the norm for managers, with a few notable exceptions. The Philadelphia Athletics’s Connie Mack and the Brooklyn Dodgers’s Burt Shotton continued to wear suits and ties to games long after it fell out of favor (though Shotton sometimes liked to layer a team jacket on top of his street clothes). Once those two retired, it’s been uniforms as far as the eye can see.

The adherence to the uniform among managers in the second half of the 20th century leads some people to think that MLB mandates it, but a look through the official major league rules [PDF] doesn’t turn up much on a manager’s dress. Rule 1.11(a) (1) says that “All players on a team shall wear uniforms identical in color, trim and style, and all players’ uniforms shall include minimal six-inch numbers on their backs" and rule 2.00 states that a coach is a "team member in uniform appointed by the manager to perform such duties as the manager may designate, such as but not limited to acting as base coach."

While Rule 2.00 gives a rundown of the manager’s role and some rules that apply to them, it doesn’t specify that they’re uniformed. Further down, Rule 3.15 says that "No person shall be allowed on the playing field during a game except players and coaches in uniform, managers, news photographers authorized by the home team, umpires, officers of the law in uniform and watchmen or other employees of the home club." Again, nothing about the managers being uniformed.

All that said, Rule 2.00 defines the bench or dugout as “the seating facilities reserved for players, substitutes and other team members in uniform when they are not actively engaged on the playing field," and makes no exceptions for managers or anyone else. While the managers’ duds are never addressed anywhere else, this definition does seem to necessitate, in a roundabout way, that managers wear a uniform—at least if they want to have access to the dugout. And, really, where else would they sit?

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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