LAB NOTES

← Entry #4: S-7 Development Notes #4 | The Salon Intuition Science Couldn’t Explain

The last chapter already had its sequel waiting inside it. Two things had come into focus — the lather, and the way hair felt after washing. The formula was starting to become an actual shape, not just an experiment.

Then, in late July 2025, I made a 1000g batch for the first time.

A 200g beaker became 1000g. Reduce it to a number, and that’s all it is. But for me, it felt like crossing a real line. 200g is an “experiment” amount — I try it on my own hair, and if it doesn’t work, I wash it down the drain and move on. 1000g is a different kind of amount. It’s enough to sit on a shampoo station in a working salon. From this version on, S-7 stopped being a liquid that only touched my own hair, and became one that might touch a client’s.

What turning it back down taught me

Actually, in the batch right before this one, I’d lowered the ratio of an ingredient that had been carrying the lather’s body. Everything was being pulled toward a milder, everyday-use direction, and that ingredient was part of the adjustment.

My hands caught it immediately.

The lather wasn’t thick enough anymore.

It still cleaned fine. Nothing was technically wrong. But it wasn’t the lather my hands remembered. If you’ve been reading this diary, you can probably already guess where this is going — yes, another one of those hand-feel stories. Ha.

So for the 1000g batch, I put the ratio back. But “putting it back” wasn’t a step backward. It was only by lowering it first that I understood exactly what that ingredient had been doing for the lather’s texture. If I hadn’t lowered it, I don’t think I’d ever have gotten that certainty.

“Eighty percent there”

I brought the finished 1000g batch into the salon and started using it.

I still have the note I wrote at the time:

“Feeling pretty good! The lather’s got its bounce back. Eighty percent of the way there for using on clients — though if the scalp’s really dirty, you need a lot more product. But it feels gentle on the hands.”

from my notes at the time

Eighty percent. That was the honest read back then. Not perfect. On hair with a lot of oil or styling product built up, the lather would disappear fast and you’d need more of it — a clear weak point that came with leaning mild.

Even so, I put it to work. I could have kept it in the lab a little longer — which, let’s be honest, was just a corner of the same salon — until it was flawless. But there’s so much you only find out by using something every single day at work. And the feel while washing isn’t the whole story anyway. Rinse-out, how conditioner sits on top of it, how easy it is to dry, what the hair feels like once it’s dry — lay all of that out, and it’s not eighty percent at all. More like forty. Ha, I’m laughing writing this, but there really was a sense of solid progress in the feel of it.

Turns out, it’s gentle on hands too

And here’s the real step forward — the thing I’d been hoping for the most.

The last line of that note: “But it feels gentle on the hands.” Honestly — and I feel a little sheepish admitting this — that mattered to me because, in a way, this shampoo is for me too.

A hairdresser washes hair many times a day. A client might shampoo once a day; we do it for person after person, every single day. Rough, cracked hands are practically an occupational hazard in this job — back when I was an assistant, I watched more than a few people quit because their hands gave out.

So the idea that I could use it every day and my hands wouldn’t scream back mattered to me as much as the lather’s texture. Honestly, if anything, it mattered more.

Think about it: a shampoo puts a hairdresser’s hands and a client’s scalp in the exact same position. The same liquid touches the washing hand and the washed scalp for the same stretch of time. The point of leaning mild wasn’t something I first understood from a formulation notebook — my own hands taught it to me before anything else did.

That “gentle on the hands” feeling from this batch went on to become something like the backbone of S-7.

Not asking one bottle to do everything

So what about the weak point — the lather not being quite strong enough?

The note from back then kept going: “If I split duty with something stronger, this might actually work for the salon floor.”

Don’t ask one product to do everything. On a day when the scalp really needs it, reach for something stronger. For most everyday washes, this milder one is enough. If anything, because it’s made for daily use, it should lean gentle rather than strong.

The “7” in S-7 is the seven days of the week. That idea had already been sitting in my head since back when all I had was a book and no name for any of this.

The test batch made it to the salon floor

A 200g experiment turned into 1000g, and made it onto the salon floor.

From here, it’s a long trip of adding, removing, and adding again. Ingredients I put in with good intentions ended up coming back out; some that disappeared once found their way back in. Next time, I want to write about that — the ingredients I tried, and chose not to use.

Deciding to leave something out is, I think, harder than deciding to add it. Against an industry that keeps piling more and more into every bottle, I went in ready to go head-to-head with simplicity and gentleness instead.

🇯🇵 日本語版（オリジナル）→ https://masashitt.com/2026/08/10/the-first-1000g-batch/

I’ll share S-7’s launch news first with the people who’ve joined the launch list.

← Entry #3: S-7 Development Notes #3 | Same Foam, So Different

The foam was, little by little, starting to do what I wanted.

Like I wrote last time, once I’d learned each surfactant’s foam by hand — once “design the combination” became my way of thinking — every test batch brought a little more progress. Foaming agent A (the one I fell for last time, the “maybe this is all I need” one) was still the front-runner. Build around A and I couldn’t go wrong. That’s what I believed, as I kept dialing in foam, slip, and viscosity.

And honestly, the in-shower feel had gotten pretty good. The lather, the texture of the foam, the clean feeling at rinse. Batches that made me go “oh, this is nice” were starting to show up.

But once it dried… it was just “fine”

The problem was what came after.

Rinse, towel-dry, blow-dry. I’m a hairdresser; this sequence is muscle memory. And the moment I ran my fingers through the dried hair, I thought the same thing every single time.

…It’s just fine, isn’t it.

So good while washing — and then, once dry, a finish you could get anywhere. Not bad. But not “this is it” either. If I’m making my own shampoo and the finish is indistinguishable from anything off a shelf, what exactly is the point…

That was the moment the problem changed. The foam, I could design now. Next up was the finish — the way the hair feels after it dries.

Tweaking the cleansing agents couldn’t reach it

At first I tried to solve it with the surfactants. Change the ratios, swap the types, shift the character of the foam.

But no matter how many times I tried, the after-dry texture barely moved. The in-shower feel would change; the post-dry feel wouldn’t.

I went back to the book — that English textbook again. Reading it only multiplied the questions. Apparently, some things never change.

So the washing process and the after-dry texture are decided in different places. Probably. Then… where?

And then I remembered that ingredient “on hold”

Here, something came back to me.

Sodium Lactate. The ingredient from entry #2 of this diary. The book called it an excellent humectant — and then added that since shampoo gets rinsed out, there isn’t much point putting it in. I’d snapped “then why even bring it up!” at the book, written “don’t get it — on hold” in my notes, and bought it anyway, oddly unable to let it go.

For no reason. (That’s literally what I wrote at the time.)

But now, something connected. The book said “pointless” because “it rinses away, so it doesn’t stay.” Fine — so where was my complaint? After drying.

Maybe the logic didn’t quite line up. But trying it costs nothing. Well, except the ingredient I’d already paid for.

So I tried it

I was skeptical. The book did say “pointless,” after all.

I added it to the formula anyway, made the batch as usual, washed as usual. While washing — honestly, no big difference. Figures, I thought, and rinsed, and dried.

The first time I thought, “this is it”

Drying done. Fingers through the hair.

…Wait. What?

Silky. Genuinely, surprisingly silky.

My fingers just slid through. That “it’s just fine” was gone. The complaint that had never once budged — the finish — finally moved. I touched my hair over and over to make sure. No mistake. Clearly different from every batch before it.

It was the first time since starting this project that I thought, “this is it.”

Not a dramatic, fall-to-your-knees kind of moment. Quiet. But certain. My hands were saying: found it.

The salon intuition science couldn’t explain

Thinking about it calmly, it’s a strange story.

The book said “it rinses out, so it’s pointless.” As logic goes, that’s probably right. It was written by someone who knows far more chemistry than I ever will.

But my hands clearly felt the difference.

It doesn’t show up in numbers or spec sheets. On paper, it’s “pointless.” And yet hands that have washed, cut, and dried people’s hair every day picked up the difference instantly. Looking back, maybe buying that ingredient “for no reason” was the same hand-instinct at work. No — that’s not true. I’d never even touched the stuff. Call it intuition. Honestly, call it a fluke.

“For no reason,” I wrote back then. But as it turned out, it led me to a wonderful ingredient.

I don’t mean to knock science. Without the fundamentals, you can’t build a formula at all. But between the textbook and the salon floor, there’s a gap the numbers don’t capture — and maybe the ones who can fill that gap are the people who’ve spent years working with their hands. Don’t you think?

Touching hair at the salon, every day — that’s all it is. I never imagined, before starting this, that it would turn out to be my biggest weapon in development.

Right after “this is it”

That ingredient “on hold” is still in S-7 today. It’s in the formula we’re fine-tuning for launch, of course.

I finally had my two pillars: foaming agent A for the foam, and this discovery for the finish. Refine these two and the goal was close — back then, I truly believed that.

…And if you’ve been reading along, you might remember. That front-runner, A, is going to disappear later, in a way I never saw coming.

But that’s for another time.

🇯🇵 日本語版（オリジナル）→ https://masashitt.com/2026/06/10/the-intuition-science-couldnt-explain/

← Entry #1: The Shampoo I Made for Myself, Not in a Boardroom

The first thing I did after deciding to make it

Last time, I wrote about how I decided to make a shampoo for myself.

Put that way, it might sound like the very next day I lined up beakers and breezily started mixing prototypes. But it wasn’t like that at all.

I’d decided, sure — but I genuinely had no idea where to even start. The one thing I knew at that point was: “Even I can buy raw materials.” That was it. (lol)

First, I read a book

So the first thing I did was read. I bought an ebook covering the basics of making shampoo. In English, of course…

As you probably know, I’m not a chemist. I’m not a formulation pro, and I never studied cosmetics at university. I’m just a hairdresser who has washed, cut, and dried people’s hair every single day.

So all I could do was read the basic books and materials, build my own “this is probably how it works” hypotheses, and check them against my own hands and hair. Having absolutely no one to ask was harder than I’d imagined…

And the moment I started reading, one thing became clear right away.

The more I read, the more — instead of feeling like I understood — the questions piled up. And because it was in English, the reading took an absurd amount of time…

So… now what? Early signs of giving up, already. lol

Sodium Lactate tripped me up right away

The first thing that snagged me was a humectant called Sodium Lactate.

According to the book, it’s an excellent moisturizer that can stand in for glycerin or aloe. “Huh, interesting,” I thought — and then read on, where it also said: since shampoo gets rinsed off in the end, adding this doesn’t really mean much.

…Wait, which is it?! If it’s a great moisturizer I want it in, but if it just rinses away there’s no point. So should I swap it for something else? Aloe, glycerin, panthenol? And honestly — if it “doesn’t really mean much,” then why even bring it up in the book?!

Looking back at my notes now, I agonized over this one single ingredient for a surprisingly long time. Normally it’s “if it rinses off, leave it out,” and you’re done. But something about it nagged at me. No reason. lol

But I suppose this is what people call intuition. That small snag would end up meaning something later. I’ll write about that a few entries down the line, though.

All I could do at the time was jot down “don’t know — on hold.” And yet, for some reason, I bought it. This ingredient.

No reason. lol (round two)

Isn’t there a bit too much surfactant?

There was one more thing that bothered me when I built my first formula by copying the book.

This recipe — isn’t the surfactant ratio pretty high? The version I mixed exactly as written felt like the cleansing agents were pushed too far forward.

Of course, at this point it was only a “felt like.” I had no real conviction. But the sense in my hands — hands that have washed people’s heads every day — was quietly saying, “this is on the strong side.”

I jotted that feeling down — the one I couldn’t put into words yet — just in case.

I’m not a scientist, so rather than rolling it around in my head, it’s faster to just move my hands. So — let’s just make one, whatever happens. That’s what I thought.

The very first prototype was…

Lather it, rinse it, dry it. The whole time, I kept my attention on how it felt against my hands, my scalp, my hair.

The foam was better than I’d expected. Honestly, a little surprising.

But the viscosity was just too thick. It wouldn’t spread in my palm, and it even took some force to squeeze out of the bottle. I’d made it exactly as the book said, and yet my hands were telling me, “this is wrong.”

The slip, too — it didn’t catch, exactly, but the way my fingers moved through was one step short of smooth.

The good and the not-good were living together inside a single bottle.

I couldn’t tell whether it had worked

Honestly, I couldn’t land on “this works” or “this is no good” either.

The foam is good. But the viscosity is thick. The slip is one step short. So where do I adjust next? — I had absolutely no idea.

For starters, I still hadn’t grasped how the “texture” of foam and slip differs from one surfactant to another. I couldn’t tell by hand which one was doing what.

What I did understand was: “I don’t have a yardstick to judge by yet.” Or, to flip it around — building that yardstick by hand is exactly what’s about to begin. So that’s how it is. Endless!!!

What was left in my hands after rinsing wasn’t success or failure — just a few complaints.

It’s exhausting. And yet, somehow, it’s fun.

But the homework, at least, was clear

Foam. Slip. Viscosity.

After washing with that first bottle, these three were the things that became clear. I didn’t know what the right answer was. But there was no longer any doubt that these were the three things my hands cared about.

Too light a foam feels lacking; too heavy and washing gets tiring. Too little slip and it catches; too much and it feels like something’s left behind. The viscosity — this bottle was clearly too thick.

These three, I would check one by one, by hand.

At this point there was still no name “S-7,” no fragrance, no finished formula — none of it.

What I had were the questions that had piled up from reading, and three complaints: foam, slip, viscosity.

I needed to pull these complaints apart and figure out which ingredient was behind each one. Endless!!! (round two)

Next time, I’ll start with the very first of the three I ran into — foam — checking it one surfactant at a time, by hand.

I share S-7’s launch news first with the people who’ve joined the launch list.

🇯🇵 日本語版（オリジナル）→

← Entry #2: The More I Read, the More Questions I Had

I used to think foam was foam.

To be honest, I barely thought about it at all. As long as it lathered, that was enough. I figured a shampoo lived or died on the “results” — how the hair felt afterward, how it held — and that the foam itself didn’t really have a personality. Right up until I started making my own, I never once questioned that.

Then I started blending it by hand, and that assumption fell apart pretty fast.

The kind of thing only your hands can tell you — and maybe only a hairdresser’s hands

There was a question I’d been carrying since last time. I wanted to really get a feel for the “slip” inside the foam. I’d started to understand, vaguely, that surfactants each have their own character. But what that actually meant, in my hands, I still couldn’t say.

Books didn’t help. Spec sheets didn’t help, no matter how long I stared at them. “Slip,” “that springy, cushiony feel” — none of it turns into numbers. It’s honestly hard to even put into words.

So there was no way around it: I had to check with my own hands, on my own hair.

And once I did, it became obvious. Even the single word “foam” covers so much — dense foam, springy foam, clean foam, heavy-slick foam — and even the way it rinses away under warm water feels different every time. The same white foam, but the way it sits in your hands is completely different.

So how do you actually design it?

So I decided to compare three surfactants, each as close to “on its own” as I could manage. It made me groan a little — this was going to take time — but there was no other way. Let’s call the three foaming agents A, B, and C.

The key here is keeping the conditions even. Match the amounts, and keep one of them in every sample as a shared base. Otherwise you never figure out what’s actually causing the difference.

It’s tedious work. But cut corners here, and you redo everything later. Put another way: get this part right, and you can actually trust the differences you see.

The same foam — so why are they this different?

When I finally lathered them up in my hands, I was genuinely surprised.

A, on its own, already had a beautiful foam. Fine, tight bubbles, great slip. Honestly, I caught myself thinking, “maybe this is all I need.” The hair felt great after rinsing, too. It would need some fine-tuning, sure — but it was clearly going to be a main ingredient.

B was underwhelming on every front — lather, slip, volume. …But there was a distinct “squeak” to the hair afterward, which left me wondering whether its cleansing power might actually be the strongest of the three. And that moderate, clean feeling seemed like it could take a foam that’s too heavy and make it lighter, without giving up the cleansing.

C was the shared base in every sample, quietly holding up the texture of the whole thing from underneath. Just adding it made the foam feel instantly richer.

I’d been lumping all of this under one word: “foam.” But the quality, the slip, the volume — they were this different.

Foam isn’t something you make. It’s something you design.

That realization became the starting point for everything, I think.

“Which foam, combined how.” That’s what making a shampoo actually is — and it finally clicked for me right here. I’d assumed foam was more or less foam. It isn’t. Foam is something you design, precisely.

So before adding anything else, I decided my first goal was to get this foam as close to my ideal as I possibly could. Fragrance, finish — all of that comes later. First, the foam.

At this point, A was still the front-runner

I’ll be honest: back then, I was pretty smitten with A.

The foam, the way the hair felt after washing — both were genuinely good. I was just happy I’d found a great ingredient without much of a struggle. Build around this, I thought, and it’ll surely turn into something good. I didn’t doubt it for a second.

…Well. This A is going to disappear later, in a way I didn’t see coming.

But that’s for another time.

🇯🇵 日本語版（オリジナル）→

I wanted a shampoo built for people who wash their hair every day

Working in a salon, I wash other people’s hair many times a day. And I wash my own hair every day too. For me — and for most people in Japan — washing every single day is simply normal.

Over the last few years, my hands had gotten pretty rough. A hairdresser’s hands dry out and get worn down; that’s not hard for anyone to imagine. I’ve always had sensitive skin, and lately the dryness was bad enough that my hands were in a genuinely tough state.

A hairdresser’s hands get washed many times a day. Easily more than twice. On average, somewhere around ten times.

Separately, some of my clients are the kind of people who want to shampoo every day. Maybe fewer than in Japan, but the people who work out daily, who sweat at the gym, who use styling products — I get asked about it a lot as their stylist: “Is it really okay to shampoo every day?”

And it hit me: these two people need the same shampoo. Something gentle enough that washing every day doesn’t wear down your hair or your body. Something gentle enough that a hairdresser can wash head after head all day without paying for it with their hands.

A shampoo for hairdressers would also be a shampoo for our clients. That was where all of this started.

What I could see precisely because I’m a hairdresser

Honestly, I’m an amateur when it comes to product development. I’m not a chemist, and I’m not a researcher at some manufacturer.

But I am someone who has watched hair and scalp as closely as it’s possible to watch them. For nearly 29 years, every day, I’ve had my hands in all kinds of people’s hair — drying it, cutting it, washing it, reading by hand what state it’s in right now.

If anything, that sense in my hands is the one piece of real expertise I have.

A slightly reckless idea: “make it myself”

Let me try making the shampoo for my own work, myself.

When the thought first came to me, I had no real basis for believing I could. If anything, there were mountains of reasons I couldn’t. But I figured it would be faster to actually make one than to keep turning it over in my head.

Not writing a proposal in a boardroom, but building it on the salon floor, checking it against my own hands and hair. That was the whole starting point.

About a year of trying, fixing, and trying again

That’s where it got long. Honestly, I made it long myself — my standards were too high.

The first prototype was, to put it kindly, not a success. The lather, the way it rinsed, how it dried. I’d given up on fragrance from the start, because I was sure it would be too hard; early on it was meant to be unscented. And yet none of it quite closed that “one more step” gap. I’d adjust a little and make another, adjust again and make another. Before I knew it, I’d been repeating that for over a year.

When I counted, there were more than twenty prototypes that never saw the light of day. The ones that didn’t work far outnumbered the ones that did.

But the time I spent checking, by hand, each reason something hadn’t worked — that turned out to be the most valuable thing I got out of it. In this development diary, I want to write about those detours honestly, without hiding them.

And it became one shampoo: “S-7”

What I arrived at, after all of that, is S-7 Daily Shampoo. You wash every day — that’s seven times a week. So, “7.”

It’s a shampoo designed for people who wash often, every day. It’s built around hydrolyzed silk protein, with a soft, silky lather, and I aimed for a finish that feels light, clean, and balanced.

Even the fragrance I’d avoided at first — because I was sure it would be too hard — eventually became something I couldn’t skip, and after a lot of trial and error I finished a scent of our own. It’s called “MATSUYAMA,” named after Matsuyama in Ehime, Japan. It’s a bright, clean scent that brings to mind Japanese citrus and the forests around a hot-spring town. I drew inspiration from a trip to Ehime, and from development through to the finish, I completed all of it in San Francisco.

I’m not going to get into the fine details of ingredients or formulation here. That will come, little by little, in the entries ahead.

Right now, I’m in the final stretch

S-7 is in the final stage of its label and packaging right now. The inside is essentially settled; what’s left is working out how it gets into your hands.

I’m not going to make some big launch-date announcement here. It will take a little more time. But the feeling that something I’ve lived with for a long time is finally taking shape — that much, I can say for sure.

This development diary is the record of it. Not an introduction to a finished, polished product, but the process itself — one hairdresser building a single shampoo with his own hands. I’d like to leave that here, bit by bit, as I go.

I’ll share S-7’s launch news first with the people who’ve joined the launch list.

🇯🇵 日本語版（オリジナル）→