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

← 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/