You went looking for an actual pre-poo oil formula: how much penetrating oil, how much sealing oil, how long to leave it in. What you probably found instead was another explainer on what "penetrating" and "sealing" mean, with a vague nudge to try both. That's not an oversight on our part either. Nobody has actually sourced a mixing ratio for this, and we're not going to invent one. What we can give you is more useful: which of our four oils genuinely earns the penetrating role, which one fits your own hair's porosity, and how to apply it so it actually works before wash day.
What penetrating and sealing actually mean, and why a pre-poo needs to pick one
A penetrating oil absorbs into the hair fiber itself. Applied before you wash, it reduces what hair blogger Lade at Rehairducation calls "hydral fatigue," the cuticle damage that happens when hair over-swells during washing. A sealing oil works differently. It sits on the surface and forms a coat rather than soaking in, which is genuinely useful for locking moisture in after you've already applied it, but it's not the job a pre-poo needs done.
Science-y Hair Blog built a chart ranking oils by how much they actually penetrate: coconut, palm kernel, and sunflower oil sit at the top; olive, avocado, argan, grapeseed, and castor land in a middle "some penetration" tier; mineral oil and jojoba barely penetrate at all. Two laboratory studies on real hair fibers, not clinical trials on people, but controlled measurements of how oil behaves on hair strands, back up the underlying mechanism. Coconut oil was the only one of three oils tested (coconut, sunflower, mineral) that reduced protein loss from combing damage in a 2003 hair-fiber study, credited to its molecular structure being small enough to actually get inside the hair shaft. A 2005 follow-up study measured oil-film thinning over time as a sign of absorption, and mineral oil never thinned at all, in either study, by either measure. That agreement matters: penetration is real chemistry tied to an oil's molecular structure, not marketing language.
Where our four oils actually fall
We checked our own four oils against this framework, ingredient by ingredient, instead of repeating the usual generic coconut-and-castor example list.
| Product | Lead ingredients | Role | Evidence |
|---|---|---|---|
| Wild Growth Hair Oil | Coconut oil, olive oil | Penetrating | Coconut oil: two peer-reviewed hair-fiber studies. Olive oil: one, showing it as a partial penetrator |
| Bask & Lather Scalp Stimulator | Grapeseed oil, hemp seed oil | Sealing-leaning | Brand's own ingredient list; no peer-reviewed penetration study |
| She Is Bomb Growth Oil (currently out of stock) | Castor oil, argan oil, almond oil, grapeseed oil | Sealing-leaning | Brand's own ingredient list; no peer-reviewed penetration study |
| Organic Extract Batana Oil | Batana oil, Jamaican black castor oil, black cumin seed oil, sunflower oil | Unclassified | Batana oil's own composition is disputed; see the open question below |
None of these four products were tested directly by the research above. We're reasoning from their actual named ingredients out to what the published science says about those same ingredients, the same standard we'd want applied to anything on our own shelf.
Wild Growth Hair Oil is the only one of the four with a peer-reviewed penetration study behind its actual lead ingredients, not a generic claim borrowed from somewhere else. That makes it the one we'd point you to first for the penetrating role in a pre-poo.
The Bask & Lather Scalp Stimulator and She Is Bomb Growth Oil aren't disqualified from anything, they're doing a different job well. Their ingredient lists lean toward oils without a documented penetration profile, which suits their own purpose better: a lighter, leave-in-style scalp product rather than a soak-in pre-wash treatment. (She Is Bomb Growth Oil is currently out of stock in our store, so it's here for the ingredient picture, not as something to add to your cart today.)
The Organic Extract Batana Oil blend is the honest exception. Batana oil's own fatty-acid makeup is genuinely disputed among the sources that write about it, so we're not going to force it into either bucket. More on why in the next section.
Match your base oil to your own porosity
Which oil fits you best depends on your own hair as much as the oil itself. Science-y Hair Blog puts it plainly: dry, porous, rough-feeling, or coarse hair tends to do well with a straight penetrating oil, while lower-porosity hair often does better with a blend, or with less penetrating oil overall.
| Your hair | What to reach for | Why |
|---|---|---|
| Visibly porous, coarse, or chemically treated | Wild Growth Hair Oil, used alone as a true pre-poo soak | The most penetration-capable option we carry, and porous hair benefits most from that |
| Lower porosity | Bask & Lather Scalp Stimulator, She Is Bomb Growth Oil once it's back in stock, or a smaller amount of Wild Growth blended in | A heavy straight-penetrating-oil treatment tends to sit heavier than lower-porosity hair actually needs |
Apply it alone, and give it enough time
Here's the part nobody puts on the label: skip the ratio. There isn't a sourced mixing ratio between a penetrating oil and a sealing oil anywhere we could find, so we're not handing you a fake one. What actually matters is applying the penetrating oil by itself, before you wash, and giving it real time to work.
Rehairducation's own guidance is to give it at least "an hour or two." Science-y Hair Blog gives a wider window, "2-12 or more hours," and notes that longer generally means more oil actually works its way in. If you can plan your pre-poo the night before wash day instead of squeezing it in an hour beforehand, you're giving the oil more room to do its job.
An open question worth knowing: does sunflower oil actually penetrate?
This is a real conflict in the peer-reviewed literature itself, not an argument between two bloggers. The 2003 study found sunflower oil gave no favorable result on protein loss, behaving more like a non-penetrating oil by that measure. The 2005 study measured something different, oil-film thinning over time, and found sunflower oil's film did thin, more so with heat, which reads as evidence of absorption.
Two research teams measured two different things and landed on two different conclusions. We're not going to pick a side the science itself hasn't settled. This matters directly for the Organic Extract Batana Oil blend above, since sunflower oil is one of its named ingredients; that's part of why we're not filing that product under either "penetrating" or "sealing."
What the growth claims actually hold up to
Castor oil and argan oil show up in two of our four oils (both in the Batana Oil blend, and argan alongside castor in She Is Bomb Growth Oil), and both get marketed around hair growth. A 2022 systematic review of the published research, the strongest evidence source in this whole article, found no strong evidence that castor oil actually grows hair, and only weaker evidence for it improving hair quality or shine. Argan oil came out with no significant supporting evidence at all for growth or hair quality.
That's not a strike against either product. It means the claim worth leaning on is moisture, lubrication, and scalp comfort, the benefits the evidence can actually back, rather than a growth promise the current research doesn't support for these specific ingredients.
Quick answers
Is Wild Growth Hair Oil really the best pre-poo base?
For porous, coarse, or chemically treated hair specifically, yes. It's the one of our four oils with peer-reviewed backing on its actual lead ingredients. If your hair is lower porosity, a lighter option is usually the better fit; see the porosity table above.Can I buy She Is Bomb Growth Oil right now?
Not at the moment. It's currently out of stock in our store, so it's included here for the ingredient comparison, not as something to add to your cart today.Does sunflower oil penetrate hair or not?
Genuinely unresolved. Two peer-reviewed studies measured it two different ways and reached two different conclusions. See the section above for both.How long should I leave the oil in before washing?
At least an hour or two, and up to 2-12 or more hours if you can plan ahead. Longer generally means more of it actually absorbs.Do these oils actually help hair grow?
The current research doesn't back a growth claim for castor oil or argan oil specifically. Lean on what it does support instead: moisture, lubrication, and scalp comfort.So here's the actual rundown: match your base oil to your own porosity, apply it alone, give it real time before wash day, and skip the ratio nobody has sourced. If your hair leans porous or coarse, Wild Growth Hair Oil is where we'd point you first.
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