Tate Williams
Tate Williams

What Exactly is Christmas Tree Flocking?

Tate Williams
Tate Williams

Of the many curious holiday traditions (figgy pudding? wassailing?), one of the oddest has to be spraying down small trees with a mixture of adhesive and cellulose fibers to satisfy our longing for a white Christmas.

That’s what’s happening when you adorn a tree with artificial snow, otherwise known as flocking. And yet, when decorated and lit up, there’s something beautiful and warmly nostalgic about a well-flocked Christmas tree. Here’s how professionals manufacture this Christmas miracle.  


We’ve been trying to get that snowy look on Christmas trees for longer than you might think, dating back to the 1800s using substances like flour or cotton. A 1929 issue of Popular Mechanics recommends varnish, corn starch, and flakes of the silicate mineral mica. 

But tree flocking as we know it really caught on in the late 1950s and 1960s, along with aluminum trees and other glitzy, if not natural-looking decor of the post-war boom. General Mills marketed Sno-Flok home kits, to be applied using a gun that attached to a vacuum cleaner.

Such home kits are not so popular these days, says Tom Leonard, owner of Peak Seasons tree lot supplier. Flocking itself, however, has retained a level of appeal. “Sunbelt states use a lot of it because there’s no snow there,” he says. “It’s tremendously popular. The West Coast, the South, and the Southeast, the vast majority of it is sold in those zones.”


davitydave, Flickr // CC BY 2.0

So what exactly is flocking? At its core, flocking means attaching tiny fibers to a surface to create texture (the process is also used in fashion, home decor, and crafts). The Peak Seasons recipe includes paper pulp as fiber, corn starch as adhesive, and boron as a flame retardant—there’s a safety benefit to flocking.

And the company makes a lot of it. Leonard says they're the largest manufacturer of flock in the United States and Europe. “I don’t want to share [how much], but we sell lots of flock. I mean truckloads and truckloads.” 

Based in sunny Riverside, California, Peak Seasons starts with paper and a grinder. “It’s like a big roll of toilet paper and it weighs a ton and you feed it into a machine and it comes out a powder.” The exception is certain bright colors—flock comes in white, black, pink, ice blue, royal blue, red, green, gold, and purple—which require cotton fibers instead of paper to hold the dye. The final product is almost like baby powder, shipped all over the country in large, cement-bag-sized bags. 

From there you need to affix the stuff in a nice even coat, which is where flock machines like the Mighty Sno-Blower come in. They’re basically big tanks that hold varying amounts of flock depending on the model, plus a mechanism at the bottom to fluff up the powder. The machine then pumps the powder through a hose, and a gun at the end mixes it with a mist of water.

And that’s how flock is born.


You don’t have to go with a professional flocker, or even use manufactured flock. There are all sorts of DIY recipes that include things like soap flakes or even desiccated coconut flakes. But if you do go pro, you want to be in the hands of someone like Paul Iantosca of Exotic Flowers in Boston. Iantosca has been flocking trees every winter for about 20 years.

Flocking one tree in bright purple (white is still most popular), Iantosca first sprays it down with water. Then, in an area of the lot closed off with plastic sheeting, he fires up the blower and blasts the tree evenly with what looks like a purple fog. The stuff gets everywhere. He wears a mask to keep it out of his nose, but some high-volume flockers wear full protective coveralls. 

The tricky part to flocking is that you can’t tell if you got it right until it dries. When it goes on, it’s cold and wet like paste. But as it dries, the Christmas magic kicks in and it puffs up, turning into fluffy white (or, in this case, purple) fuzz firmly affixed to the needles.

There are pitfalls. Not enough water, and the flocking falls off and makes a huge mess. A flocked tree can’t get wet a second time. “It won’t dry again. It’s disgusting actually,” Iantosca says. Also, when you flock a tree, the color highlights its flaws. A janky tree turns into a weird, uneven shrub.

But if you get it right and string it up with lights, you’ve got a real stunner on your hands. Iantosca’s had flocked trees for his own home for the past 10 years and his kids won’t let him go back.

“When you plug that thing in, it absolutely glows inside. It’s unbelievable.”

Big Questions
Why Do Onions Make You Cry?

The onion has been traced back as far as the Bronze Age and was worshipped by the Ancient Egyptians (and eaten by the Israelites during their bondage in Egypt). Onions were rubbed over the muscles of Roman gladiators, used to pay rent in the Middle Ages, and eventually brought to the Americas, where today we fry, caramelize, pickle, grill, and generally enjoy them.

Many of us burst into tears when we cut into one, too. It's the price we pay for onion-y goodness. Here's a play-by-play breakdown of how we go from grabbing a knife to crying like a baby:

1. When you cut into an onion, its ruptured cells release all sorts of goodies, like allinase enzymes and amino acid sulfoxides. The former breaks the latter down into sulfenic acids.

2. The sulfenic acids, unstable bunch that they are, spontaneously rearrange into thiosulfinates, which produce a pungent odor and at one time got the blame for our tears. The acids are also converted by the LF-synthase enzyme into a gas called syn-propanethial-S-oxide, also known as the lachrymatory factor (or the crying factor).

3. Syn-propanethial-S-oxide moves through the air and reaches our eyes. The first part of the eye it meets, the cornea, is populated by autonomic motor fibers that lead to the lachrymal glands. When syn-propanethial-S-oxide is detected, all the fibers in the cornea start firing and tell the lachrymal glands to wash the irritant away.

4. Our eyes automatically start blinking and producing tears, which flushes the irritant away. Of course, our reaction to burning eyes is often to rub them, which only makes things worse since our hands also have some syn-propanethial-S-oxide on them.

It only takes about 30 seconds to start crying after you make the first cut; that's the time needed for syn-propanethial-S-oxide formation to peak.


The onion's relatives, like green onions, shallots, leeks and garlic, also produce sulfenic acids when cut, but they generally have fewer (or no) LF-synthase enzymes and don't produce syn-propanethial-S-oxide.


Since I usually go through a good deal of onions while cooking at home, I've been road testing some of the different methods the internet suggests for reducing or avoiding the effects of the lachrymatory factor. Here's what I tried:

Method #1: Chill or slightly freeze the onions before cutting, the idea being that this will change the chemical reactions and reduce the gas that is released.
Result: The onion from the fridge has me crying just as quickly as room temperature ones. The one that was in a freezer for 30 minutes leaves me dry-eyed for a bit, but by the time I'm done dicing my eyes start to burn a little.

Method #2: Cut fast! Get the chopping over with before the gas reaches your eyes.
Result: Just hacking away at the onion, I get in the frying pan without so much as a sting in my eyes. The onion looks awful, though. Doing a proper dice, I take a little too long and start tearing up. If you don't mind a mangled onion, this is the way to go.

Method #3: Put a slice of bread in your mouth, and cut the onion with most of the bread sticking out to "catch" the fumes.
Result: It seems the loaf of bread I have has gone stale. I stop the experiment and put bread on my shopping list.

Method #4: Chew gum while chopping. It keeps you breathing through your mouth, which keeps the fumes away from your eyes.
Result: This seems to work pretty well as long as you hold your head in the right position. Leaning toward the cutting board or looking right down at the onion puts your eyes right in the line of fire again.

Method #5: Cut the onions under running water. This prevents the gas from traveling up into the eyes.
Result: An onion in the sink is a hard onion to cut. I think Confucius said that. My leaky Brita filter is spraying me in the face and I'm terrified I'm going to cut myself, but I'm certainly not crying.

Method #6: Wear goggles.
Result: In an effort to maintain my dignity, I try my eyeglasses and sunglasses first. Neither do me any good. The ol' chemistry lab safety glasses make me look silly, but help a little more. I imagine swim goggles would really do the trick, but I don't have any.

Method #7: Change your onion. "Tear free" onions have been developed in the UK via special breeding and in New Zealand via "gene silencing" techniques.
Result: My nearest grocery store, Whole Foods, doesn't sell genetically modified produce or onions from England. Tonight, we eat leeks!

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

Big Questions
What is Mercury in Retrograde, and Why Do We Blame Things On It?

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding for the first time this year on Friday, March 23. But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

"We don't know of any physical mechanism that would cause things like power outages or personality changes in people," Dr. Mark Hammergren, an astronomer at Chicago's Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?


Mercury retrograde—as it's technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an "ill omen" also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

"Don’t start anything when Mercury is retrograde," an April 1979 issue of The Baltimore Sun instructed its readers. "A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication." The power attributed to the event has become so overblown that today it's blamed for everything from digestive problems to broken washing machines.


Though hysteria around Mercury retrograde is stronger than ever, there's still zero evidence that it's something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. "A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does," Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the Sun is retrograde, it appears to move "backwards" (east to west rather than west to east) across the sky. This apparent reversal in Mercury's orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the Sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the Sun, Mercury looks like it's moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it's just a trick of perspective. "Same thing if you were passing a car on a highway, maybe going a little bit faster than they are," he says. "They're not really going backwards, they just appear to be going backwards relative to your motion."

Embedded from GIFY

Earth's orbit isn't identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the Sun than Earth have even more noticeable retrograde patterns because they're visible at night. But thanks to astrology, it's Mercury's retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: "[Believers] will say, 'Aha! See, there's a shake-up in my workplace because Mercury's retrograde.'" He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They'll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn't retrograde, "we don't get that hashtag. It's called Monday."

This story originally ran in 2017.


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