How is paper made?

Summary

Brains On! Episode Summary: "How is Paper Made?"

Podcast Information:

• Title: Brains On! Science podcast for kids
• Host/Author: American Public Media
• Description: Brains On!® is a science podcast for curious kids and adults from American Public Media. Each week, a different kid co-host joins Molly Bloom to find answers to fascinating questions about the world sent in by listeners.
• Episode: How is paper made?
• Release Date: January 7, 2025

---

Guest Hosting and Introduction

In this special episode of Brains On!, Rosie Dupont takes the helm as a guest host alongside Aria from Acton, Massachusetts. Molly Bloom, the regular host, is away, but Rosie ensures that the episode remains as engaging and informative as usual.

Rosie Dupont:

"Hi, Aria. So today's episode is about how paper is made. We've gotten a lot of questions about it over the years." (02:02)

---

Understanding Paper: Materials and Sources

Aria begins the discussion by highlighting the ubiquity of paper in our daily lives.

Aria:

"There’s printer paper and pizza boxes, toilet paper, wrapping paper, sandpaper, diapers, books, wallpaper, receipts, and even money, honey." (02:33)

The conversation quickly shifts to the fundamental component of paper—cellulose.

Aria:

"It's made from plants. Cellulose, to be exact. The stuff that makes plants stiff and strong." (05:08)

Dr. Sanford Smith (Sandy), a teaching professor in forestry at Penn State University, provides an in-depth explanation of cellulose and its role in plants.

Dr. Sandy:

"And there's thousands upon thousands of them, millions of them in any stem of a tree or branch. And they're all stuck together with a special kind of glue called lignin." (07:37)

While the United States primarily uses wood from trees to produce paper, the episode explores alternative sources utilized globally due to varying availability.

Aria:

"In other parts of the world, when they don't have a lot of trees, they use the plants they do have a lot of." (15:07)

Sri Ramaswamy, a professor in bioproducts and biosystems engineering at the University of Minnesota, elaborates on these alternatives.

Sri Ramaswamy:

"Bamboo is a resource that is available in some parts of the world. So places in Asia, it is an option. The alternative are similar to bamboo. In South America, they actually use sugarcane bagasse, which is a residue after you take out the sugar from sugar cane, and that can be also used in making paper." (15:30)

Notable Quote:

"What's cool about that sugarcane paper is that it's made from materials leftover after you turn sugar cane into sugar crystals. So it's stuff that otherwise would have been trash or burned for energy, but instead it's paper." (15:55)

---

The Paper-Making Process

Dr. Sandy takes listeners through the intricate journey of turning trees into paper.

1. Cutting and Debarking:

   • Trees are cut down, and their branches are removed.
   • The trunks are loaded onto trucks heading to paper mills.
   • Aria:

     "Debarking is when you rub the bark off the tree trunk in a tumbling machine." (08:33)

2. Chipping and Digestion:

   • The trunks are chopped into wood chips and placed into a digester.
   • The digester uses chemicals and steam to soften the chips.
   • Dr. Sandy:

     "The digester has lots of chemicals in it, and it's heated up with steam to very high temperatures. And those chips break down and get very soft." (08:48)

3. Separation of Lignin:

   • Lignin is separated from cellulose during the cooking process.
   • The lignin is often burned to create energy for the mill.
   • Dr. Sandy:

     "Cells and that lignin is dissolved and taken away. And most of that lignin goes into the power plant of the mill. They burn that to create energy." (09:08)

4. Pulp Formation:

   • The remaining cellulose breaks down into fine fibers, creating a pulpy liquid.
   • Aria:

     "What you're left with is a soupy liquid called pulp, which is made of liquid and lots of little cellulose fibers." (09:31)

5. Paper Production:

   • The pulp is spread onto large screens at high speeds within paper machines.
   • The fibers are dried and pressed into flat sheets of paper.
   • Dr. Sandy:

     "At the paper mill, the magic is turning old paper into new." (20:00)

Notable Quote:

"The whole process is going so fast. And these rolls of paper come out at the end and they're huge. They're huge. They're several tons thick." (09:51)

---

Recycling: Giving Paper a New Life

The episode delves into the importance and process of recycling paper, emphasizing environmental sustainability.

Aria:

"In the US we recycle over 60% of all paper and around 90% of all cardboard." (17:02)

Dr. Sandy personifies recycled paper as "Crumplestiltskin," sharing the journey of recycled fibers.

Dr. Sandy (Crumplestiltskin):

"You see, when you drop that paper in a bin with all your other recyclables, it sets off on a journey that is both long and winding... At the paper mill, the magic is turning old paper into new." (19:20)

Recycling Process:

1. Collection:

   • Used paper is collected and taken to a materials recovery facility.
   • Dr. Sandy:

     "We get to ride this fun little conveyor belt and plastic and paper and metals all get sorted by machines." (19:01)

2. Processing:

   • Paper is shredded and mixed with water and chemicals to form pulp.
   • Contaminants like staples and plastic are removed.
   • Dr. Sandy:

     "First, we're shredded into little pieces. Then they dump water and chemicals on those pieces to turn them into soupy pulp." (20:08)

3. Reforming:

   • The clean pulp is spread into sheets, flattened, and dried to create new paper products.
   • Dr. Sandy:

     "And once you have your pulp, all you have to do is make it into a sheet, flatten it and dry it." (20:25)

Sustainability Insights: Sri Ramaswamy highlights the environmental benefits of paper compared to plastics.

Sri Ramaswamy:

"Paper is actually coming from a renewable resource and it is recyclable. It's reusable. So from that point of view, I don't think one has to feel that, oh, I'm using paper, I'm actually affecting the environment in a negative way. Right. At least in the U.S." (16:11)

Notable Quote:

"It's not that. It's just at some point, the fibers and recycled paper are just too worn out to be reused. And my fibers are old. Most paper can be recycled five to seven times." (21:06)

---

Interactive Segments and Fun Facts

Throughout the episode, Rosie and Aria engage listeners with interactive segments, including the Mystery Sound game and encouraging creative participation.

Mystery Sound Highlight:

• Rosie introduces the segment where listeners guess sounds related to the episode's theme.
• Notable Guess:

  "I think it might be someone stapling something amazing." (11:55)

Fun Fact: Rosie:

"Of course, in the United States, we recycle over 60% of all paper and around 90% of all cardboard." (17:00)

---

Conclusion and Key Takeaways

The episode wraps up with a recap of the paper-making and recycling processes, emphasizing the significance of sustainability and the versatile uses of paper.

Molly Bloom:

"We learned that paper is made out of cellulose, the stuff that makes plants stiff and strong." (14:52)

Aria:

"We turn the plants into pulp and then machines dry it and make paper." (15:01)

Final Thought:

• Molly Bloom:

  "When we recycle a piece of paper, it's turned back into pulp and made into paper again." (21:48)

Through engaging dialogue, expert insights, and interactive elements, this episode of Brains On! effectively demystifies the complex process of paper production and recycling, fostering a deeper appreciation for the materials we often take for granted.

---

Notable Quotes with Timestamps:

• Rosie Dupont:

  "How is paper made? How is paper made from trees?... " (02:09)

• Dr. Sandy:

  "The trunk of a tree is actually millions upon millions of tiny little pipelines going up to make paper." (07:46)

• Sri Ramaswamy:

  "Paper is actually coming from a renewable resource and it is recyclable." (16:11)

• Dr. Sandy (Crumplestiltskin):

  "At the paper mill, the magic is turning old paper into new." (19:20)

---

This comprehensive summary encapsulates the key discussions, insights, and educational content delivered in the "How is Paper Made?" episode of Brains On!, providing listeners with a clear understanding of paper production and recycling.

Transcript

[Molly Bloom]

You're listening to Brains on, where we're serious about being curious. Brains on is supported in part by a grant from the National Science Foundation.

[Rosie Dupont]

I love teepee. Teepee is for me.

[Aria]

Molly, do you have any toilet paper? All the bathrooms and Brains On HQ are out.

[Rosie Dupont]

Yeah, sorry about that. I needed to use all of it.

[Aria]

What? You needed to use all of the toilet paper?

[Dr. Sanford Smith]

Yes.

[Rosie Dupont]

Yeah, for my new favorite activity, going to the bathroom. Decorating toilet paper.

[Aria]

Oh, okay.

[Rosie Dupont]

It's so fun and it makes every visit to the loo a potty party.

[Aria]

I'm so happy for you. Can I have a roll? I really have to go.

[Rosie Dupont]

Sure. Pick one that feels exciting to you. I've got tie dye, camouflage, rainbow. Oh, and I do custom toilet paper portraiture.

[Aria]

Just gimme. Whatever.

[Rosie Dupont]

No, no, you have to pick. I want you to have a perfectly personalized pot.

[Aria]

Oh, fine. I'll take this one.

[Rosie Dupont]

Great choice.

[Aria]

Wait, does every sheet have Gungador's face on it? Oh, no, no, no, no, no, no. How about this one?

[Rosie Dupont]

The garden variety? Oh, that's perfect for you, Rosy Rose. There's a hand drawn flower on every sheet. And it's scented too. Give it a whiff.

[Molly Bloom]

Mmm.

[Aria]

I'll take it.

[Rosie Dupont]

Here you go.

[Aria]

Thanks.

[Rosie Dupont]

Oh, and that reminds me. I'm headed to a toilet paper crafting conference later today and I need someone to guest host an ep. Would you be up for it?

[Aria]

Oh, yeah. What episode?

[Rosie Dupont]

How is Paper Made?

[Aria]

Oh, my gosh, that's perfect. I'm obsessed with paper, origami, paper mache, maybe even toilet paper. Who knows? I can't wait to guest host Molly. But first, I just gotta try this super special Made with love toilet paper. Love it. Love you. Gotta go. You're listening to Brains on from APM Studios. I'm Rosie Dupont. Since Molly Bloom is away, I have the honor of guest hosting with Aria from Acton, Massachusetts. Hi, Aria.

[Molly Bloom]

Hi, Rosie.

[Aria]

So today's episode is about how paper is made. We've gotten a lot of questions about it over the years.

[Molly Bloom]

How is paper made? How is paper made from trees? How is paper made? How is paper made out of wood? How is paper made? And how can we prevent more trees from being cut down?

[Aria]

Big thank you to Gabe, Harriet, Faye Xiaofeng, Cassie and Ashlyn for sending in your questions. And I gotta say, it makes sense that people are curious about paper because paper is all around us.

[Molly Bloom]

There's printer paper and pizza boxes, toilet.

[Aria]

Paper and wrapping paper, sandpaper, diapers, books, wallpaper, receipts, and even money, Honey. Aria, what kinds of activities do you use paper for at school?

[Molly Bloom]

Sometimes in books, for writing stuff down.

[Aria]

Mm. Like journals?

[Molly Bloom]

Yeah.

[Aria]

Do you use it in art class?

[Molly Bloom]

Art class? Like, I like making crafts a lot.

[Aria]

Like, what kind of crafts?

[Molly Bloom]

Maybe sometimes I do origamis.

[Aria]

You can do origami?

[Molly Bloom]

Yeah.

[Aria]

Like, what does that look like?

[Molly Bloom]

It's like folded pieces of paper come to 3D sometimes.

[Aria]

That's so cool. And what kind of 3D shapes are you building?

[Molly Bloom]

I can make, like, a swan.

[Aria]

Whoa.

[Molly Bloom]

Yeah. I can do a little bit of, like, a ninja star that can make rabbits, cats, foxes.

[Aria]

That's awesome. I love that you're so crafty. And so do you count paper planes as part of origami?

[Molly Bloom]

Yes, I do, because origami's is basically when you fold paper to make an object and you fold paper to make a paper airplane. So. Yeah. Yeah.

[Aria]

That's so cool. And how far has your best paper plane flown?

[Molly Bloom]

I don't know. I did this, like, really cool trick. So it was like, my brother made one and I made one, and then you know how, like, you can open the paper airplane so we stuffed another paper airplane in it.

[Aria]

What? Wait, how does that work?

[Molly Bloom]

I don't know, but it was, like. It was really cool. So then you threw it, and they would do, like, a circle in the air, and it would just fall. It was really cool. So they would spread apart.

[Aria]

Wait, the two planes would separate from each other?

[Molly Bloom]

They would separate and then they would go and maybe wind down one circle, and then they would fall.

[Aria]

That's really, really cool.

[Molly Bloom]

Yeah.

[Aria]

You're making me want to go out and try origami.

[Molly Bloom]

Yeah.

[Aria]

So can you name for me the things that are made out of paper that you touched today?

[Molly Bloom]

Notebooks, books, like, regular pieces of paper, paper towels, tissue papers. I think that's pretty much it.

[Aria]

Yeah. I mean, that's pretty similar to me, I'd say. I also. It was definitely like, tissue, coffee, filter, pages of, like, you know, a pamphlet I got in the mail. Yeah, Yeah. A box of, like, for crackers. Because I love crackers. And I have to say, a lot of toilet paper.

[Molly Bloom]

Oh, yeah.

[Aria]

You know what? We touch it all the time, and we often don't even remember that it's paper.

[Molly Bloom]

True. So there's all this different stuff made from paper, but what's paper itself made out of?

[Aria]

It's made from plants. Cellulose, to be exact. The stuff that makes plants stiff and strong. You know how when you bite into a stick of celery, it's all stringy inside?

[Molly Bloom]

Well, that stringy Stuff is made up of cellulose.

[Aria]

And here's a fun fact. You can make paper out of celery.

[Molly Bloom]

Whoa. Cool.

[Aria]

Yeah, you can make paper out of almost any plant.

[Molly Bloom]

Seaweed. Mm, Bananas.

[Aria]

The peels. Yeah. And cotton and linen. That's what dollar bills are made of. And some toilet paper is made of bamboo. For real? Just ask Molly.

[Molly Bloom]

But today, most of the paper in the world comes from wood. And wood comes from trees.

[Aria]

Lets imagine a tree I'm picturing. It's an oak and it's super tall and it's covered in rough bark and it's got all these acorns. What kind of tree are you picturing, Aria?

[Molly Bloom]

A cherry tree.

[Aria]

What does it look like?

[Molly Bloom]

It's all pretty in spring with its pink and white flowers waiting to be bloomed into cherries.

[Aria]

Oh, it sounds so pretty. I love cherry trees. Yeah, and both of our trees are very, very strong. And unlike celery, snapping a tree trunk in half is not so easy.

[Molly Bloom]

That's because the cellulose in trees is super strong.

[Aria]

Way stronger than celery. Trees need to be tough so they don't tip over in the wind.

[Molly Bloom]

But that's not all trees.

[Sandy]

They have to grow very stiff, woody stems and branches to hold their leaves up to the sky so they can get sunlight so they can produce food for themselves.

[Aria]

That's Dr. Sanford Smith.

[Sandy]

I just go by Sandy. And I work at Penn State University where I'm a teaching professor in forestry. The art and science of tending forests.

[Molly Bloom]

Sandy knows a lot about trees and how they get turned into paper.

[Aria]

And he says inside trees there are tons of cellulose cells.

[Molly Bloom]

Cells are the teeny building blocks that make up every plant and animal.

[Aria]

And just like our muscles are made up of tiny muscle cells, tree wood is made up of tiny cellulose cells.

[Sandy]

And there's thousands upon thousands of them, millions of them in any stem of a tree or branch. And they're all stuck together with a special kind of glue called lignin.

[Aria]

And these cellulose cells are really important for the tree. They're hollow inside and they carry water and food up and down the trunk like pipes.

[Sandy]

So the trunk of a tree is actually millions upon millions of tiny little.

[Aria]

Pipelines going up to make paper. You take all these pipe shaped cellulose cells and pull them apart into tiny.

[Molly Bloom]

Fibers and then those fibers get turned into paper.

[Aria]

But how does it all work? Well, let's imagine for a minute that we're a tiny cellulose cell.

[Molly Bloom]

One minute we're helping move water up and down inside a tree. I just love being a little cellulose cell.

[Sandy]

In the next minute, the tree has been cut down and sent to a paper mill.

[Molly Bloom]

Forest floor, here I come.

[Aria]

The tree's branches get cut off and the trunk is loaded onto a truck that heads to a paper mill.

[Molly Bloom]

And then when it gets there, the trunk is debarked.

[Aria]

Debarking is when you rub the bark off the tree trunk in a tumbling machine.

[Molly Bloom]

Woo hoo.

[Aria]

What a Next, the tree is chopped into wood chips and loaded into a big tank called a digester. Here's tree expert Sandy again.

[Sandy]

The digester has lots of chemicals in it, and it's heated up with steam to very high temperatures. And those chips break down and get very soft.

[Aria]

Remember how Sandy said the cellulose cells in trees are stuck together with a natural glue called lignin? Well, when you cook the wood chips, the lignin glue separates from the cellulose.

[Sandy]

Cells and that lignin is dissolved and taken away. And most of that lignin goes into the power plant of the mill. They burn that to create energy.

[Molly Bloom]

As the wood chips cook, the cellulose cells fall apart into little strands of fiber.

[Aria]

And what you're left with is a soupy liquid called pulp, which is made of liquid and lots of little cellulose fibers.

[Molly Bloom]

The cellulose fibers and pulp are very tiny, thinner than human hair.

[Aria]

And the pulp soup, it's mostly liquid.

[Molly Bloom]

Scrub a dub dub cellulose in a tub.

[Aria]

So there's a lot of liquid to get rid of. And they do that in the paper machine. Sandy says these machines are huge.

[Sandy]

So paper machines are really a series of machines that are all joined together and they're longer than a football field. They're huge. And at the wet end of the paper machine, that's where you're putting in the wet fiber. It goes in there and it starts going across a screen, a large screen like a house screen, and it spreads.

[Molly Bloom]

Out and these big screens filled with pulp start moving fast, about 70 miles an hour. Woo hoo. Life is a highway I wanna ride it all night long.

[Aria]

They run through a bunch of different rollers and heaters. By the time the screens filled with pulp reached the other end of the paper machine, the cellulose fibers in the pulp have been dried out and pressed flat into paper.

[Sandy]

The whole process is going so fast. And these rolls of paper come out at the end and they're huge. They're huge. They're several tons thickness.

[Aria]

These rolls of paper get cut up or shipped out to Be turned into other paper products.

[Molly Bloom]

And that little cellulose fiber is off on a new adventure. Ta ta friedle. I hope I become an envelope full of surprises. Or maybe a paper doll with a kill. I want to be a paper snowflake.

[Aria]

Have fun, fiber friend. There are so many ways to play with paper that I haven't even thought of yet. Listeners, we asked you to send us pictures of paper creations you've made, and you sent us a ton of amazing things. We've posted pictures of your work on our brains on universe social media channels. Ask your parents to show you. Okay, we're going to talk more about paper in a bit, but first it's time for the.

[Molly Bloom]

Mystery sound.

[Aria]

All right, Aria, are you ready for the mystery sound?

[Molly Bloom]

Yes.

[Aria]

Great. Okay, great. Here it is. Okay, Aria, what do you think it is?

[Molly Bloom]

I think it might be someone stapling something amazing.

[Aria]

Do you want to hear it one more time?

[Molly Bloom]

Yes, please. Hmm.

[Aria]

Has your answer changed or is it the same?

[Molly Bloom]

No, I think it's the same.

[Aria]

Okay, so stapling paper.

[Molly Bloom]

Yeah.

[Aria]

Okay, great. Well, we will hear the answer after the credits. At the end of the show, we're making an episode all about Jupiter, the biggest planet in our solar system. And it got us wondering, if planets had personalities, what would they be like and what would their nicknames be? Maybe Jupiter would be super tough and go by Jupiter. Or Mercury would be tiny and spunky and go by mini Merc. If you could give a nickname to any planet in our solar system, what would it be and why? What do you think, Aria?

[Molly Bloom]

Hmm, Maybe I would name Saturn.

[Aria]

Mm.

[Molly Bloom]

Mm. The diamond ring planet, because Saturn already has a ring around it. And why not add a diamond?

[Aria]

That's so cute. I love it. That's such a good nickname.

[Molly Bloom]

Thank you.

[Aria]

Well, listeners, record your planet nickname and send it to [e-mail] contact. While you're there, send us your mystery sounds, drawings, and questions like this one.

[Molly Bloom]

What happens in your body when you get sick?

[Aria]

You can find answers to questions like these on the moment of podcast, a short dose of facts and fun every weekday. Find moment of and [e-mail] so keep listening. Brains on Universe is a family of podcasts for kids and their adults. Since you're a fan of Brains on, we know you'll love the other shows in our universe. Come on, let's explore.

[Molly Bloom]

Brains On. I'm their biggest fan. I'd also love Forever ago, a fun history podcast for the whole family. Listen, I will play you forever Ago. Now you will love.

[Rosie Dupont]

Homing pigeons were a speedy way to deliver messages to military bases. Some pigeons could fly hundreds of miles in a single day, zipping through the air as fast as 60 miles per hour.

[Molly Bloom]

That's so fast for such a tiny bird.

[Rosie Dupont]

These pigeons delivered life saving messages throughout the war.

[Aria]

Zorp.

[Molly Bloom]

Where did the signal go? Must find Forever Ago.

[Aria]

Now listen to Forever Ago wherever you get your podcasts.

[Molly Bloom]

Rain Song Dawn. You're listening to Brains on. I'm Aria.

[Aria]

And I'm Rosie. And today we're talking about paper and how it's made.

[Molly Bloom]

We learned that paper is made out of cellulose, the stuff that makes plants stiff and strong.

[Aria]

In the United States, most paper is made out of trees.

[Molly Bloom]

But in other parts of the world, they don't have as many trees. So what do they do?

[Aria]

We spoke with Sri Ramaswamy. He's a professor in bioproducts and biosystems engineering at the University of Minnesota. He knows all about things made from renewable resources. These are things in nature that can be replaced if we use them like trees.

[Molly Bloom]

He says in other parts of the world, when they don't have a lot of trees, they use the plants they do have a lot of.

[Sri Ramaswamy]

Bamboo is a resource that is available in some parts of the world. So places in Asia, it is an option. The alternative are similar to bamboo. In South America, they actually use sugarcane bagasse, which is a residue after you take out the sugar from sugar cane, and that can be also used in making paper.

[Molly Bloom]

Whoa, sugar cane paper. Sweet.

[Aria]

And what's cool about that sugarcane paper is that it's made from materials leftover after you turn sugar cane into sugar crystals. So it's stuff that otherwise would have been trash or burned for energy, but instead it's paper.

[Molly Bloom]

Very earth friendly.

[Aria]

Exactly. But even in the United States, the paper industry is good about replanting new trees after they cut old ones down.

[Molly Bloom]

And Sri says paper that isn't recycled can easily break down and become part of nature again, unlike many other materials.

[Sri Ramaswamy]

That we use, many of the plastic that we use, for example, paper is actually is coming from a renewable resource and it is recyclable. It's reusable. So from that point of view, I don't think one has to feel that, oh, I'm using papers, I'm actually affecting the environment in a negative way. Right. At least in the U.S.

[Molly Bloom]

Rosie, want to hear a cool fact?

[Aria]

Is kale an excellent source of dietary fiber?

[Molly Bloom]

Of course, in the United States, we recycle over 60% of all paper and around 90% of all cardboard.

[Aria]

Go us.

[Molly Bloom]

We rock.

[Dr. Sanford Smith]

Ah. I remember the first time I was recycled like it was yesterday.

[Aria]

Who said that?

[Molly Bloom]

I think it was that old birthday party hat on the ground.

[Dr. Sanford Smith]

Party hat. Construction paper postcard from beautiful downtown Boise, Idaho. I've been a lot of different things, but at the end of the day, it's all the same. I'm paper. My name is Crumplestiltskin. Crumple for short. Unlike my life, which has been so, so long.

[Aria]

Oh, so you've been recycled. We'd love to hear about it.

[Molly Bloom]

Yeah, I've recycled paper all my life, but I've never gotten to hear what happens from a piece of paper's point of view. This is neat.

[Aria]

Neat?

[Dr. Sanford Smith]

You think being turned into an endless array of papers and paper related products, including one time, a postcard for Boise, AKA the City of Trees, is neat?

[Molly Bloom]

Yeah.

[Dr. Sanford Smith]

Great, because it is neat. Very neat. I'm truly blessed.

[Aria]

Truly. So how does it work?

[Dr. Sanford Smith]

Well, Rosie, you ever make chocolate chip cookies from scratch on a cold winter day?

[Aria]

Yeah. Is recycling paper like that?

[Dr. Sanford Smith]

Not at all. You see, when you drop that paper in a bin with all your other recyclables, it sets off on a journey that is both long and winding. Not unlike the Boise river, from which scenic Boise gets its name. By the way, did I mention I was once recycled into a postcard for beautiful Boise, Idaho?

[Molly Bloom]

Yes, you did. Several times.

[Dr. Sanford Smith]

You never forget your first recycle. Anyway, it all starts when the used paper is taken to a place called a materials recovery facility. Ah, I get giddy just thinking about it. We get to ride this fun little conveyor belt and plastic and paper and metals all get sorted by machines. Sometimes workers pick out all the small stuff that shouldn't be in there. One time I saw a toilet seat in the mix.

[Crumplestiltskin]

That's definitely not a recyclable.

[Dr. Sanford Smith]

I know. So why.

[Aria]

So after everything is sorted, then what happens?

[Dr. Sanford Smith]

Well, Rosie, us paper pieces are weighed and packed and shipped off to our next destination. Another paper mill. Can you believe it? You probably can, because it's very believable. It is the paper mill. Oh boy. As people from Boise would say, this is where the magic happens. At the paper mill. I mean, not Boise. The magic happens there too, but it's much more of a community built feeling of belonging. At the paper mill, the magic is turning old paper into new.

[Aria]

That's pretty impressive too. Tell me, Crumple, how exactly do they take all those different kinds of paper with different colors and inks and make them new again?

[Dr. Sanford Smith]

First, we're shredded into little pieces. Then they dump water and chemicals on those pieces to turn them into soupy pulp. Stuff like staples and paper clips and tapey tape gets filtered out. Then more chemicals and air bubbles. They help get rid of all the inks.

[Molly Bloom]

So basically, the old used paper gets turned back into a pulp. Just like how trees are turned into a pulp to make new paper.

[Dr. Sanford Smith]

Yeppies. And once you have your pulp, all you have to do is make it into a sheet, flatten it and dry it. Then it's ready to be something new. Like a carrier for coffee cups, a pamphlet, or if you're lucky, a postcard showing off the many scenic forest surroundings the city of Boise has to offer. It's what every scrap of paper dreams of. But I'm afraid my recycling days are almost over.

[Molly Bloom]

Don't worry, Mr. Old Paper Guy. We'll still be sure to recycle you after this.

[Dr. Sanford Smith]

It's not that. It's just at some point, the fibers and recycled paper are just too worn out to be reused. And my fibers are old. Most paper can be recycled five to seven times. And this birthday hat is my seventh recycle. I'm not sure if I've got an eighth one in me, but you know what? You said you believe in me.

[Aria]

Uh, we did.

[Dr. Sanford Smith]

That's good enough for me. I'll give it a shot. Throw me in that recycling bin. Let's see if ol Crumple has one more life left in him. This one's for Boise.

[Aria]

Paper is made from something found in plants called cellulose.

[Molly Bloom]

In the US we use trees to make paper, but other countries use things like bamboo.

[Aria]

We turn the plants into pulp and then machines dry it and make paper.

[Molly Bloom]

When we recycle a piece of paper, it's turned back into pulp and made into paper again.

[Aria]

And that's it for this episode of Brains On.

[Molly Bloom]

This episode was written by Rosie Dupont and Sandon Totten.

[Aria]

It was edited by Shayla Farzon. Engineering help from Gary O'Keefe and Jim Sullivan, with sound design by Rachel Breese and fact checking by Jess Miller. Original theme music by Mark Sanchez.

[Molly Bloom]

We had production help from the rest of the Brains On Universe team.

[Rosie Dupont]

Molly Blue, Anna Goldfield, Nico Gonzalez Whistler, Ruby Guthrie, Lauren Humphryt, Joshua Wright, Mark.

[Aria]

Sanchez, Charlotte Traver, Anna Wegel and Aron Woldeselassi. Beth Pearlman is our executive producer and executives in charge of APM Studios are Chandra Kavati and Joanne Griffith. Special thanks to Sandipan Sarma and Urchana Upadiy.

[Molly Bloom]

Brains on is A non profit public radio program.

[Aria]

There are. There are lots of ways to support the show. Subscribe to Brains on universe on YouTube, where you can watch animated versions of some of your favorite episodes. Or head to brainson.org while you're there.

[Molly Bloom]

You can send us mystery sounds, drawings, and questions.

[Aria]

Okay, Aria, are you ready to listen to the mystery sound again?

[Molly Bloom]

Yep.

[Aria]

All right, here it is. Okay. So you said it was stapling paper before. Is that still your same guess?

[Molly Bloom]

No. Cause now I kind of feel like people. It's like footsteps kind of walking. Oh, I just really don't know.

[Aria]

Do you want to hear it one last time?

[Molly Bloom]

Yes, please.

[Aria]

Yes. Mm. Here comes.

[Molly Bloom]

No, it's definitely stapling paper. I can hear the paper getting stapled together and I can hear them moving it.

[Aria]

Okay, fantastic guess. Let's hear the reveal.

[Molly Bloom]

Okay. My name is Ellie and I live in Monroe, Louisiana. And that was the sound of me cutting paper.

[Aria]

Cutting paper so close. Stapling paper is like, almost like cutting paper because you're still punching holes in paper. Yeah, I think you get. You definitely get partial credit.

[Molly Bloom]

Okay.

[Aria]

Cutting paper.

[Molly Bloom]

It must be with one of those, like, zig style scissors. Like, they have like. Like, designs on them. And when you cut paper with them, it makes, like, that kind of sound. Mm.

[Aria]

They almost look like the scissors themselves look like alligators. Yeah, yeah, yeah, yeah, those are cool. Now it's time for the Brains honor roll. These are the incredible kids who keep the show going with their questions, ideas, mystery sounds, drawings, and high fives.

[Crumplestiltskin]

Mike, Ethan and Abby from Jackson Heights, New York. Benny from Dublin, Ohio. Lilith from Lexington, Kentucky. Lucas from London, England. Judah from Columbia, Maryland. Colt from Olath, Kansas. Elon from Sydney, Australia. Michaela from Oak Park, Illinois. Declan from Wisconsin. Henry and Arlo from Littleton, Colorado. Iggy From Del Mar, N.Y. jing Yi from Oakville, Ontario. Oliver from Gifu, Japan. Felix from Las Vegas. Dom from Langhorne, Pennsylvania. Allen from Grand Rapids, Michigan. Val from San Diego, California. Alexandra from Cambridge, Massachusetts. Isla from Toronto. Chinmaya from San Carlos, California. Martha Lucia from San Leandro, California. Josh from Elk Mound, Wisconsin. Harlow from South Bronx, New York. Cakes from Wellington, New Zealand. Noah from New Mexico. Aria from Sydney, Australia. Benny from Montclair, New Jersey. Charles from la, Canada. Flintridge, California. Riley from Bedford, Massachusetts. Jacob and Owen from Denver. Elliot and Theo from Calgary, Alberta. Aziz and Rafiq from West Hartford, Connecticut. Mana from Toronto, Hudson from Merrick, New York. Emily from Three Rivera, Michigan. Sophie from Winnipeg, Manitoba. Darcy from Butterham, Australia. Anais and Amaya from Waterloo, Ontario, Olive and Ellie from Austin, Texas Holly from Phoenix, Arizona Talia and Asher from Austin, Texas Jensen and Etta from Coon Rapids, Minnesota Eleanor and Luke from Dallas, Texas Will from Neenah, Wisconsin Ian and Leonie from Charlotte, North Carolina, ZJ from Champaign, Illinois, Erin from Vancouver, Marshall from Virginia Beach, Sariah from Bedford, New Hampshire Eliza from Hershey, Pennsylvania Jeram and Jolie from Eden Prairie, Minnesota Abigail and Josephine from Amherst, New York Oakland from Sandy, Utah Lucci from Upton, Massachusetts Robert from Murrieta, California Jonah from Edmond, Oklahoma Kevin and Amy from Fullerton, California Clover from Freeport, Maine Teddy from Los Angeles and Wallace from Calgary, Al.

[Aria]

We'Ll be back next week with an episode all about down syndrome.

[Molly Bloom]

Thanks for listening.