Skincare & Ingredient Expert

What the evidence supports. And what is marketing in a lab coat.

Independent skincare and ingredient guidance. I read the studies behind the claims on the front of the bottle and tell you how strong they really are — including when the honest answer is “thinly supported”.

  • Everything in writing, with named sources
  • One product at a time, twelve weeks before a verdict
  • No diagnosis, no promised results, no affiliate links
Jessica Hartwell in a white lab coat in a bright consultation room
Testing rule Forearm patch first. One active at a time. Four weeks minimum.

Who she is

I say “that is thinly supported” more often than I say “this is a gamechanger”. That is the whole job.

Jessica Hartwell reading from her notebook at the window

I have worked with skin for years, and I spend a slightly unreasonable amount of my own time reading the actual papers behind the claims on the packaging. Most of what I do is not recommending products. It is sorting out which claims have data underneath them, how strong that data is, and which ones are a texture being described in scientific language.

I test one product at a time, for at least four weeks, starting on a patch on my forearm. Every test goes into a notebook by hand, because “I think it is a bit better?” is not data and my memory is not either.

What I will not do: tell you a ninety-dollar cream replaces a procedure, call anything a miracle, diagnose anything, or pretend that the routine which suits my skin will suit yours.

More about how she works

Services

Four ways to work together

All of it is guidance and evidence, in writing, that you keep. None of it is diagnosis or treatment.

Routine Review

We go through everything you currently own. What stays, what goes, what order it belongs in — with a reason attached to every line, not just a verdict.

  • How it runsYou send a short questionnaire and photos of the products. You get a written assessment back.
  • Turnaround3–5 working days

Not: not a diagnosis, and not a judgement on your skin — only on what is in the bottles.

Ingredient Check

One product, or one list. What the evidence actually supports, how strong it is, and which part of the claim is doing the marketing.

  • How it runsSend a link or the ingredient list. You get a short written assessment with named sources.
  • Turnaround48 hours

Not: not a safety clearance and not a recommendation to buy.

1:1 Consultation

A conversation. You bring the questions, we work out what matters first and what can wait a year.

  • How it runs50 minutes online, followed by a written summary so you are not relying on your notes.
  • Turnaround50 minutes

Not: not a medical appointment. If something needs examining, you need someone who can examine it.

Twelve Weeks

My testing rule as an accompanied format: one product at a time, forearm patch first, everything written down. Most “this does not work” is really “I did not give it a chance”.

  • How it runsOpening call, a protocol template, two check-ins, a closing call.
  • Turnaround12 weeks

Not: not a promise of a result. It is a method for finding out honestly whether there was one.

See what each one covers

Jessica Hartwell explaining a product to a client across her consulting table
In the room Products and evidence on the table. No diagnosis, no treatment.
How a session looks

You bring the bottles. She brings the papers.

Most of a session is spent on two questions: what does this product actually contain, and what does the evidence behind that claim actually say. Those are different questions, and the gap between them is where most skincare money goes.

Nothing is applied to your face and nothing is examined. You get a written record of what stays, what goes, and the reasoning for each line — so you can check it later, or take it to someone else.

See what each service covers

Areas

What people bring her

The subjects that come up most often. She works on the products and the evidence behind them — the skin itself stays with the people qualified to examine it.

A barrier that stopped coping

Tight, stinging, reactive skin after too many actives at once. Usually a subtraction problem, not an addition one.

Actives and how to combine them

Retinoids, acids, vitamin C, niacinamide — what genuinely conflicts, and which warnings are formulation folklore.

Sun protection that actually protects

Which filter, and far more importantly how much of it, how often, and where everyone misses.

Pigmentation and uneven tone

What topicals can realistically shift, over what timescale, and where the honest ceiling of a cream sits.

Ageing claims, sorted by evidence

Retinoids and sunscreen have the data. Most of the rest is a texture described in scientific language.

Reading a label properly

INCI order, concentration claims, “clinically proven”, and what a percentage on the front does and does not tell you.

Too many products

The most common finding: eleven products, three doing the work, two cancelling each other out.

A study someone quoted at you

What it measured, on whom, for how long, and how much of the claim survives the reading.

None of this is diagnosis or treatment. Where something needs examining, she says so and stops there — that is the actual limit of the work, not a disclaimer bolted on.

Method

How she tests anything

It is deliberately boring. That is why it works, and why it is a hard sell.

  1. 01

    Forearm patch first

    Everything goes on the same patch of forearm before it goes anywhere near a face. It costs three days and saves the occasional fortnight.

  2. 02

    One product at a time

    Two new things at once means that when something happens, you have learned nothing. One change, then wait.

  3. 03

    At least four weeks, twelve before a verdict

    Skin turns over on its own schedule and does not care about the launch calendar. Anything faster than four weeks is describing a texture, not an effect.

  4. 04

    Written down by hand

    Date, product, what the skin did. Memory rewrites itself to match what you hoped for. The notebook does not.

Journal

What the evidence says this week

Ingredient explainers, routine mistakes, and the occasional myth taken apart. Sources named, no before-and-afters.

All entries

Case notes

How the thinking looks in practice

Anonymised, and deliberately without results. What is interesting is the reasoning, not a photograph.

Routine Review

Eleven products, three doing the work

Four of them were the same active in different packaging, two were cancelling each other out on the same evenings, and the sunscreen was being used at about a third of the amount it was tested at. We removed six and changed nothing else for eight weeks.

Ingredient Check

A strong ingredient, quoted from the wrong study

The formula was reasonable. The evidence being quoted for it had been collected on an injected version in a clinical setting — a different product in a different context. Worth buying, on completely different grounds than the ones on the box.

Twelve Weeks

The retinoid that “did not work”

It had been abandoned twice in week three, both times during the phase where it looks like it is going badly. Third attempt, lower frequency, everything else stripped back. The point was not the product. It was finishing the test.

Clients

What people say afterwards

She talked me out of two things I was about to buy and did not replace them with anything. I did not expect that.
Routine Review
The first person who answered “is this worth it” with an actual number instead of an adjective.
Ingredient Check
I stopped changing things every fortnight. That was the entire advice, and it was the right one.
Twelve Weeks
A row of unlabelled glass bottles and jars on a shelf in daylight
Enquiries

Tell her what you are trying to sort out

A sentence or two about what you are using now and what is bothering you is enough to start.

Usually within two working days. No diagnosis and no treatment — see what each service actually covers.