Brynn MacLennan: Co-Founder & CEO of Slate Flosser

Episode 867

On today’s episode, we welcome Brynn MacLennan, Co-Founder and CEO of Slate Flosser — a women-led oral care company on a mission to transform flossing from an overlooked chore into one of the most important habits in preventive health. A product designer, entrepreneur, and mother of five, Brynn built Slate after recognizing that flossing wasn’t a motivation problem—it was a design problem. What started as a Kickstarter project evolved into a seven-figure company and the #1 dentist-recommended electric flosser on the market.
In this episode, Brynn shares how purchasing a dental practice opened her eyes to the connection between oral health and overall health, and why she believes the mouth is one of the most overlooked gateways to longevity. We discuss the three-year journey of developing Slate’s patented 3-in-1 electric flosser, the challenges of disrupting a stagnant category, and how thoughtful product design can change consumer behavior. Brynn also opens up about scaling from a garage invention to a nationally recognized brand, building a women-led company culture, balancing entrepreneurship with raising five children, and why a simple 60-second daily habit can have a meaningful impact on long-term health outcomes.
A must-listen for founders, product innovators, health enthusiasts, and anyone interested in prevention, behavior change, and building a brand that solves a real-world problem.

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Transcript

Kara Goldin 0:00
I am unwilling to give up. That I will start over from scratch as many times as it takes to get where I want to be. I want to be. We just want to make sure you will get knocked down, but just make sure you don’t get knocked out. Knocked out. So your only choice should be go focus on what you can control. Control. Control. Hi everyone, and welcome to the Kara Goldin Show. Join me each week for inspiring conversations with some of the world’s greatest leaders. We’ll talk with founders, entrepreneurs, CEOs, and really some of the most interesting people of our time. Can’t wait to get started. Let’s go. Let’s go. Have you ever wondered why flossing is still the habit so many people skip, even though we all know it matters? Our next guest saw that problem differently. To her, flossing wasn’t just a motivation issue; it was a design issue, and of course, one of health. So today, I’m excited to be joined by Brynn MacLennan, who is the co-founder and CEO of Slate Flosser, a female-led oral care company rethinking one of the most overlooked habits in preventive health. After purchasing a dental practice, Brynn saw firsthand how much of our mouth brushing alone doesn’t reach, and how oral health is connected to much more than teeth. With a background in product design, she spent years developing a patented dentist invented three-in-one electric flosser designed to make flossing easier, more effective, and something people actually want to do. I cannot wait to get into the story of Slate Flosser. Have read all about the Kickstarter, and obviously got to try the products, and am a huge, huge fan. So I’m excited to dig into.

Brynn MacLennan 2:02
Thank you. You’re welcome.

Kara Goldin 2:04
So I’m excited to dig into Bryn’s journey from product to CEO to how Slate is continuing to grow in a crazy world that we live in today. So Bryn, welcome to the Kara Goldin Show, so excited to have you here!

Brynn MacLennan 2:23
I’m so glad to be here and have the opportunity to talk on your show. So thank you,

Kara Goldin 2:28
very excited. So, so for listeners just discovering Slate Flosser, also known as Slate, how do you describe the brand and what makes it different from maybe traditional oral care products.

Brynn MacLennan 2:41
Yeah, so our product. My co-founder was a dentist, and we knew that people knew they needed to floss, but they didn’t do it. And so for me, I was like, one, it’s hard, and two, it’s because people don’t really understand why they need to floss. So we have like two missions at site: one’s to educate people so that they’re like, wait, this is connected to dementia. I’m gonna floss, or this is connected to erectile dysfunction. I’m gonna floss, you know. And so once we have the knowledge, that’s gonna help us change. But what we’d notice was the biggest factor was the design issue. And so as a product designer teaming up with the dentist, we were like, “Let’s make this so it removes the bacteria that we’re all missing. So that’s our goal at Slate is to disrupt the whole mouth, and that’s why it’s actually called Slate, is because we want your mouth to be a clean slate.

Kara Goldin 3:33
Oh, I love it! I was going to ask you that how you came up with the name. I absolutely love that. So take us back to the beginning. So you had been a product designer. Obviously, your co-founder is the dentist. But it’s one thing to have this idea. It’s another thing to actually go and develop a product and a company, and you know, go and get into incredible partnerships as you have with Target, etc. But take us back to the beginning. What what were the initial steps that you took, and why did you believe that this had to be you?

Brynn MacLennan 4:12
So so many things. One is is at the dental office when we had patients come in, we had educated, wealthy patients. So there’s literally no reason why they shouldn’t be flossing. They had the funds to buy whatever products they needed, and I was like, they’re not doing it. So I saw the patient interaction, and I actually had a patient that had raging gum disease, and his choice was to like get his teeth extracted and get dentures or to floss, and I was like, floss. It’s not hard. So, with like my background in product design, Doctor Schneider was like, what if we made a product that made flossing so easy? And so, we were like, what are the multiples of products that we want people to use in the dental office? So we want people to. Scrape. We want them to stimulate their gums. We want them to floss. Everyone understands the toothbrushing part, but our product does all three of those things, and so it not only goes between the teeth, but it stimulates the gums with our gum sweeps and then tongue scrapes on the back.

Kara Goldin 5:15
What is it about flossing that you think has kept people from doing it. Obviously, it’s like just another step. I mean, people want to brush their teeth, but you would think that they would want to floss them as well. But it’s ironic, really, that some people just don’t do that.

Brynn MacLennan 5:35
Well, it was interesting because I grew up in a house where I flossed my teeth every single day, and so like I didn’t get why people weren’t flossing, but what I realized is when people have inflamed gums, and 50% of Americans do, it’s like a negative, sometimes a negative tactile experience when they use string floss because they jam their gums, then they see blood, then it hurts, their gums are sore. So we’re like, what if we made it so it was a positive tactile sensation, so that it’s like after you brush your teeth, you know you feel your teeth and they feel clean, and that’s like what if after you’re flossed, you also had a positive interaction, and so our sonic vibrations paired with our our gum sweeps go in and they give people a positive positive feedback, so they’re not jamming their gums anymore, and it feels feels so clean. Like you just went to the hygienist.

Kara Goldin 6:26
How long did it take you from the time you had this idea to actually launch Slate Flosser?

Brynn MacLennan 6:33
Well, almost took three years. So we started thinking about it in 2019. In 2020, we applied for our patent. In 2021, we did our Kickstarter, and then we had product to sell by the end of 2022.

Kara Goldin 6:45
That’s amazing. So let’s talk about the Kickstarter because I know many people think, okay, I don’t have the money to actually go and launch a company. Can you talk about your experience and how did you get that idea as well?

Brynn MacLennan 6:59
Yeah. So in the product design world, a lot of people use Kickstarter. It’s funny if I actually went back, I probably wouldn’t have done this. But I think it’s because I’ve learned so much. I think you need to the, but the it was really cool. We were in the top 5% of all Kickstarters. So the the reason I like the Kickstarter is is it proved the proof of concept. We knew people liked brushing their teeth, but for years and years, no one’s been flossing. So I was like, we may care about flossing because we’re in the dental industry, but how do we make sure the consumer cares? And so doing the Kickstarter did show a really good proof of concept. We were able to make about $200,000 doing our Kickstarter, so it was really great feedback we had. And then the great thing about Kickstarters is you have an engaged group of people that want you to succeed, and so you can ask them questions. And so there are a lot of positives about Kickstarter. A few things that we learned in the Kickstarter that was negative was you have to price your product right, and we hadn’t really figured out how much shipping was going to cost, and so we had we had just made it so our margins were really tight with our Kickstarter.

Kara Goldin 8:15
So you launched with one product, and how has that changed over over the last four years.

Brynn MacLennan 8:23
Yeah, so we launched with just one product. It was our battery powered Fosser, and had a button on the bottom. We learned so much. We got a lot of feedback from people. It was a really good price point. It was 7999 for our battery one, and then people were like, “We want it to be rechargeable. And what we’ve learned about like our consumers is, is we have different types of consumers, and because of that, we launched our rechargeable. But then we learned people really wanted a more affordable price point too. So we now have three different products: a mini, an origin, and a pro, and then we also have five different floss heads. So we’ve had a lot of product expansion, and it’s been really exciting.

Kara Goldin 9:11
So can you talk about the different products? So you launch with one, and then you just mentioned the pro as well as the mini, so can you talk about the different ones and maybe what are the differences between all of them?

Brynn MacLennan 9:26
Yeah, so let me start with our floss heads because the cool thing about them is they’re compatible across our whole product line, and so what we realized was the reason flossing maybe didn’t work for people using floss picks is because they flossing is technique sensitive. They’re supposed to do a C shape

Kara Goldin 9:44
if

Brynn MacLennan 9:45
you’re using string floss, but the the average person wasn’t doing the C shape, so they could use a floss pick and go to their dentist, and their dentist would be like, “Are you flossing? You’re like, “I floss every day. You’re like, “Well, I can’t tell, and. So our product and the little gum sweeps are meant to mimic that C shape. So they go into where your gums and teeth touch, and they’re going to pull out the plaque and bacteria with the little bristles and ridges that they have. So our floss heads are super cool that way. But we have three different kinds and different colors. So we have a braces head for people in wired braces. Then we have our standard head, which is designed to act like a glide floss, but we didn’t want any chemicals on our floss, so we didn’t want PTFEs or PFAS. So our floss is a woven floss, but is laid out in a way for it to go between your teeth really easily, and then our third kind of floss is our nano hydroxyapatite floss. So, we our consumers are really focused on longevity and wellness and health, and and they said, how do we get something in there? And so, at Slate, you know, fluoride is also a good remineralizing agent, but people are our average consumers sometimes doesn’t like fluoride, so we we offer nano hydroxyapatite infused into the floss in our blue and green floss heads. So once you have our floss head, that’s like our magic is the floss heads. Then you have the three different options: our origin, which is our battery, has one speed. It’s powered by a AA, which means you can take it all over the world with you, and you don’t have to think about charging it or different things like that. And the battery lasts a really long time, so you know you can use it for a few months, and then you’ll need a new battery. Our pro is you know three different settings for three different types of people. You know, some people. Our favorite setting is the middle. It’s 1200 sonic vibrations. It’s about the third of a toothbrush. But what we saw is some people don’t like intense vibrations. So we have a lower setting at 8000 And then for people who have really tight contacts, we don’t want them to have a negative experience of jamming their gums, so we have a higher setting at 14,000 sonic vibrations, and we don’t want it to be much higher than that because we don’t want to hurt our gums. You know, our gums are sensitive, and people sometimes can be aggressive with their gums. So we made it so that the floss is great; it’s really tight, but the sonic vibrations travel all the way to the floss, and because of that, we stop it at 1400 And the the actual floss

Kara Goldin 12:30
pieces now are those you dispose of those every day, whatever you’re flossing, or

Brynn MacLennan 12:37
so 52 of our heads is equivalent to 736 floss picks, so you replace it once a week.

Kara Goldin 12:43
Amazing!

Brynn MacLennan 12:44
So just like your toothbrush, you’re going to rinse it off and let it air dry. It’s crazy. Like four football fields worth of string floss is the same as 52 of our heads. So we’re really trying to also reduce waste. We’re from the Pacific Northwest. We love being outdoors, and anything we can do to reduce waste is great.

Kara Goldin 13:06
Yeah, no, that’s what I absolutely loved loved about it. So after you developed the the product, I guess you were you spent a few years actually developing it. When did you know that the Slate Flosser was not just a product, but a real business. Right, that you would scale, and that this wasn’t just a Kickstarter campaign anymore. When did you know that you had you had it?

Brynn MacLennan 13:37
I think there’s two things that matter to me. We’ve seen in the oral health industry that there’s been a few companies that have amazing marketing, and the consumer gets behind it, but the dentist doesn’t. And so we cared about both. We wanted the consumer to be excited about us and the dentist. So we sent our product to 500 hygienists and 200 dentists and said, “What do you think of this? 70-4% of them said it was better than any tool that existed on the market at massaging and stimulating the gums. So that moment was like, okay, we got the dentist and hygienist to back us. But our first year in business, we did over a million dollars in sales, and that was like by word of mouth and different things, and so I was just like, okay, people do want to floss; they want an easier way, and we just made it easy. So I think the first year we had sent our product to a dentist called Ask the Dentist. He he’s on Instagram. He’s a well well known, and he posted organically about our product, and just said like, I tried this and I loved it, and I was just like, this is so exciting. And then we were lucky enough to be on the How I Built This episode with Guy Raz, and Guy Raz had tried our product, and he said on the podcast. I love this product, so I just think it’s really easy for people to use. It’s under they understand why they’re using it, and then they’re like, “Oh, and there’s a tongue scraper on the back. So it’s just like it’s just fun, kind of have like some surprise and delights, and we’re really excited to be part of people’s wellness journey.

Kara Goldin 15:20
I love it. Well, I felt really happy about it because I loved. I’ve always felt like all the string that you have to take out and and floss with, and you know what is happening to that product. Yeah, in you know once you throw it away, the waste that comes from it. So I loved that there’s less waste here, and plus the experience of it. I thought it was just absolutely terrific. So when you’re developing any product, you first of all, it takes more time, right, than you ever thought. So

Brynn MacLennan 15:59
much time. We thought we’d have it by the beginning of 2022, and we were wrong.

Kara Goldin 16:04
Yeah, and was there a pivot involved? I hate to say failure. There are like learnings that maybe surprises when you were developing the product that you saw that really kind of forced you to kind of think maybe what you originally thought.

Brynn MacLennan 16:25
Yeah, I think there’s definitely a lot of grit involved in a startup, especially when you’re developing a product. We decided to start our product in the Philippines, and I loved our factory, but you know, like there were so many things we didn’t realize. Like, okay, our plastic’s going to come on a boat to the Philippines, but sometimes people in the government at the Philippines would hold it there until they were given money behind the table, you know, to get it off the port. And I was just like, “Oh, this is a little bit crazy. So I think that we had a lot of failures, and I think it’s really good for actually people to sometimes even address them as failures because the companies that are successful are the ones that fail and then get back up and figure it out because it’s gonna happen all the time. Like tariffs were a big failure for us; they had to make us pivot. Even this, the oil the oil issue is a new problem that we’re dealing with now, and so I think it’s the companies that problem solve their failures and learn from them that that end up succeeding.

Kara Goldin 17:35
So besides doing away with bad breath, you mentioned some of the other health benefits that you get just from flossing. Can you talk a little bit about the education side of Slate Flosser and and how does the 62nd habit really outsize the impact of the hassle? I guess factor that you get from it.

Brynn MacLennan 18:00
Well, what I didn’t realize till I was working at the dental office is that 50% of Americans have gum disease after the age of 30. Like you, you think, oh, maybe it’s when they’re older, but then once you’re 60 years old, it’s 70% And so, what happens is I didn’t realize that when your gums bleed, that means the blood-brain barrier is broken. So within 30 seconds, the germs from your mouth are now going to your brain, and to your heart, and to your gut, and so you’re like, okay, there’s this germ called Porphyromonas gingivalis that is found in the brains of people with Alzheimer’s, and they know that if you have gum disease for more than five years, which is a lot of the population, you have a 70% increase of getting dementia. I’m like, whoa, okay. Now that I know that, I’m going to floss. Something also that was really interesting for me is is I flossed my whole life, and then I had pregnancy gingivitis, which is really, really common. So, 70-5% of women, according to the CDC, have pregnancy gingivitis, and this leads to low birth weight and preterm labor. And if you like know that, you’re like, oh, well, I’m going to floss something that also like blew my mind that I learned was men with gum disease are two to three times more likely to experience erectile dysfunction, and I was like, crazy! All you have to do is floss for 60 seconds, and it’s not even 60 seconds if you just do your whole mouth. And sometimes people don’t realize. So I always like to say your gums are kind of like a turtleneck sweater. So when they’re healthy, they’re like tight, but when they get less healthy, they get loose, and then the bacteria sits inside your turtleneck, and that bacteria. Actually, like, sends warning signals to your brain. They’re called osteoclasts, and those are told to eat away the bone. And so, people like just don’t realize, like, okay, my body’s way of trying to clean out the bacteria is to send in these osteoclasts, and these osteoclasts are then going to eat my bone, and once the bone is gone, it cannot get get better. But your gums can bounce back. So I always tell people, like we are flossing, so our bone can hold our teeth in.

Kara Goldin 20:33
So education obviously is a key factor, I guess, in your company. But how much of that is kind of forward facing, right, to the consumer? How much does the consumer want to hear that, and what does that cause? You’ve you’ve grown the brand in Amazon and DTC. Like I think it’s always this challenge, right, internally because do you want to focus on the education side of it, even though it’s like incredibly important, or is it just super fun to be able to floss and do what you’re able to accomplish with the Slate Flosser?

Brynn MacLennan 21:14
Yeah. So there’s actually this is actually something I struggle with because I’m like a data wellness person. So like naturally, intrinsically to me, I want to tell everyone about the science of why they should be healthier. But what I learned is, is not everyone cares about that. So we have different, you know, personas in our company. We have a huge group of people who do really care about the wellness, the longevity side. But then there’s other people that are like, I just want it to be easy. So I think for our brand to really grow, we need both. But more realistically, the consumer just wants it to be easy, and so I think that’s why we are our early adopters of our company. Though are typically the wellness longevity focused people, like who also care about sustainability and things like that.

Kara Goldin 22:02
What about the kids market? I’m curious how much that, because obviously it’d be so much better if you get them starting early, right? But how much of a focus has that been for your company?

Brynn MacLennan 22:16
I think that it’s really, really great. So you know, this is something I focused on because the amount of children I have, I was like, I have to get them to floss when they’re little, and so the mini is actually one of the reasons we made the mini was for kids to be able to take it, which is meant to replace floss picks, so it doesn’t have the sonic vibrations, but they can put it in their backpack and now they can floss at school. My little five-year-old, he just you know can floss his teeth all by himself, and so I think it’s almost I relate this to like making your bed. It’s like if you make your bed as a little kid, you’re gonna make your bed your whole life. So if you floss as a little kid, you’re gonna floss your whole life. Are you gonna do a perfect job as a little kid, no, your bed’s not going to be fully tight and perfect and have no. But I just think it’s great when we can have habits that we can form as a younger person, so that they can be carried through our whole life. I think that we see it was actually like one of my biggest, proudest moment as a mom is I have a 13-year-old, and one of her friends asked for a slate for her birthday, and I was like, “Oh my gosh, the 13-year-olds are wanting to floss now. My life is made. So I don’t know. We’ll see how it goes.

Kara Goldin 23:34
I love it. So, have you raised money beyond beyond the Kickstarter campaign?

Brynn MacLennan 23:40
Yeah. So we’ve raised about $3 million so far. We did a series seed, a very beginning one in 2022 and we raised about $800,000 then. And and then when we got into Target, we were like, okay, we need to do another raise. So we raised just about $2 million to do that.

Kara Goldin 24:01
That’s incredible. So, when you think about the hardest part of actually launching and growing a company, what would you say?

Brynn MacLennan 24:13
So, customer adoption is not cheap. So, making sure that you get people organically to know about your brand. I think is the hardest part because you can pay for ads and people can learn about your company that way. But if you can get them to learn about it through community and organic reach is the best. I think for me, the beginning of the company was really hard making sure we had the product coming. I just I remember one night I was laying in my bed and I was just like I don’t know if this is gonna work. Like I don’t know if I can make this be successful, but it was be it was it was just like I just had to get the product. There were there were issues with like leaving the fill. Teams and getting here, and it just like sometimes that cash flow can feel so intense to a business owner.

Kara Goldin 25:08
Yeah, for sure. Looking back, like knowing what you know now, is there anything that you would change along the way? You had mentioned the Kickstarter. You know that there were pieces like that? Do you think that you would not do certain things or go a different direction?

Brynn MacLennan 25:26
I think it’s so hard because every time you fail, you learn something, and so I probably wouldn’t do the Kickstarter again. But I was like, but that also gave us proof of concept. I probably would have started manufacturing in China instead of going into the Philippines, but you know, I didn’t want my because it’s like a brand new invention. I didn’t want to get knocked off. We had a problem on Amazon where we got reported as a product, and it really messed up our our Amazon for a little while. I like wish that wouldn’t have happened. I was like, what could I have put in place? But I think something that I wish I would do better as a CEO is realize how far I’ve come. Because anytime I do something, I’m just like, “Okay, let’s move on and be bigger and better for the next thing. But I remember I went with a group of female founders, and at that time, I was like, I just want to make like a half a million dollars. It was at the very beginning, and I sometimes don’t realize those steps. Like, all I wanted at that point was to do a half a million dollars, and now I’m like, okay, now I want to make exponential, exponentially more, and so sometimes realizing where you’ve come in such a short time is something I wish I did more as a as a CEO.

Kara Goldin 26:51
Yeah, I love that so much. Well, Brynn, thank you so much for joining me today. For everyone listening, be sure to check out Slate Flosser. We’ll have the info in the show notes. But you are doing such an incredible job of growing this company. The product, the products are awesome. So I love the tongue cleaner. Like you said, that was like a surprise and delight for me. I was like, oh wow, this this is awesome! So I absolutely love it, and also follow Brynn on social and her team and see what they’re building. So thank you again, Bryn. Really appreciate it, and thank you everyone for listening. Bryn McLenon, co-founder and CEO of Slate Flosser.

Brynn MacLennan 27:41
Thank you so much. And if someone is super data driven, they can listen to my TED talk that gives you all the data on the different benefits of flossing.

Kara Goldin 27:50
I love it. All right, great. Thank you again. Thanks again for listening to the Kara Goldin Show. If you would, please give us a review and feel free to share this podcast with others who would benefit, and of course, feel free to subscribe so you don’t miss a single episode of our podcast. Just a reminder that I can be found on all platforms at Kara Goldin. I would love to hear from you too, so feel free to DM me. And if you want to hear more about my journey, I hope you will have a listen or pick up a copy of my Wall Street Journal best-selling book, Undaunted, where I share more about my journey, including founding and building. Hint: We are here every Monday, Wednesday, and Friday. Thanks for listening, and goodbye for now.

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