The Science Behind Brow Bomber

Before we talk about what Brow Bomber does, it’s important to understand what a brow hair actually is.

Each brow hair is a highly organised keratin-based fibre, built in layers and held together by internal bonds that determine its strength, elasticity, and natural shape. At the centre is the medulla (often absent in fine facial hair), surrounded by the cortex — the main structural body of the hair. The cortex contains long chains of keratin proteins and melanin pigment, and it’s where the hair’s strength, flexibility, colour, and ability to change shape come from. Around this sits the cuticle, made of overlapping, scale-like cells that protect the cortex and regulate how moisture and chemicals move in and out of the hair.

What gives brow hair its natural direction, curl, and rigidity are the disulfide bonds inside the cortex. These bonds act like internal bridges between keratin chains, locking the hair into its natural form. The density, thickness, porosity, and processing history of the brow determine how many of these bonds are present and how resistant they are to change.

Every brow hair is therefore a balance of:

• structure (keratin proteins)

• protection (cuticle layers)

• and internal bonds (especially disulfide bonds)

Brow lamination doesn’t work on the surface — it works by temporarily restructuring these internal bonds, allowing the artist to redirect the hair before stabilising it again.

Step 1 – Lift 1

Lift 1 is the stage where Brow Bomber begins working inside the hair fibre.

At the centre of every brow hair are keratin proteins, stabilised by disulfide bonds. These bonds form between sulphur atoms and act as internal anchors — giving the hair its natural rigidity, direction, and resistance to change.

The active ingredient in Lift 1 is ammonium thioglycolate, a proven professional reducing agent. When applied, it diffuses through the cuticle and into the cortex, where it donates electrons to disulfide bonds. This reduces them into sulphydryl (–SH) groups, breaking the internal links that lock the hair into its original form.

This is known as the reduction phase.

To allow this process to happen evenly and predictably, Lift 1 uses ammonia to raise the pH. This gently swells the hair fibre and lifts the cuticle scales, allowing controlled penetration of the reducing agents into the cortex.

As these bonds are reduced, the keratin network becomes temporarily flexible. The hair is no longer fixed — it becomes responsive, mouldable, and able to be redirected by the artist.

At the same time, Brow Bomber’s formulation supports the fibre and skin during chemical change:

• Glycerin helps maintain moisture balance

• Fatty alcohols support cream structure, slip, and even distribution

• Tocopheryl acetate (vitamin E) contributes to skin comfort

• EDTA stabilises the system and improves performance reliability

Lift 1 does not create the final result.

It creates the conditions for change — softening internal structure while preserving fibre control, so the brow can be reshaped before bonds are reformed in Step 2.

This is why timing, placement, saturation, and continuous brow checks are essential.

The goal is not maximum breakdown — it is controlled structural softening.

Step 2 – Lock 2

The oxidation phase: where structure is re-formed and the new shape is stabilised

Lock 2 is the phase where the brow hair is not just “set” — it is chemically restructured into its new form.

After Lift 1, many of the disulfide bonds inside the cortex have been reduced into sulphydryl (–SH) groups. The keratin network is softened and flexible, allowing the hair to be repositioned — but at this stage, the hair is also structurally unstable.

Lock 2 introduces hydrogen peroxide, an oxidising agent. When it penetrates the cortex, it removes electrons from the sulphydryl groups, allowing them to re-oxidise and reform disulfide bonds.

This is known as the oxidation phase.

As these new disulfide bonds form, they reconnect keratin chains in the new physical arrangement created by the artist. This is what stabilises the brow into its lifted, redirected shape.

At the same time, Lock 2’s acidic pH (2.5–3.5) helps to contract the hair fibre and smooth the cuticle layers, supporting structural consolidation and surface refinement after the alkaline swelling of Step 1.

The emulsifier system ensures even distribution and controlled action, while etidronic acid stabilises the hydrogen peroxide, improving consistency and reliability throughout processing.

Lock 2 does not “freeze” the hair.

It rebuilds the internal architecture.

This step determines:

• strength of the new shape

• longevity of the result

• and long-term fibre stability

Which is why processing time, hair positioning, and thorough yet gentle removal are critical.

In the InLei® Brow Bomber system, Step 2 is not a pause between steps.

It is the moment where cosmetic change becomes structural change.

InLei® Tint + Developer

Where cosmetic colour becomes structural colour

Tinting in a Brow Bomber service is not simply a surface stain. When performed at the correct point in the system and with the correct chemistry, it creates a true oxidative colour change inside the hair fibre.

After Lock 2, the hair has undergone reduction and re-oxidation. New disulfide bonds have been formed, stabilising the brow in its new direction. The cuticle has largely re-contracted, but the hair fibre remains in a controlled, receptive state — not fully sealed, not overly swollen.

This is the ideal moment for oxidative tinting.

InLei® tints are oxidative hair dyes. When mixed with InLei® Developer (1.5% hydrogen peroxide), small colour precursor molecules penetrate through the cuticle into the cortex. Inside the hair, hydrogen peroxide oxidises these precursors, allowing them to bind together into larger, coloured dye molecules.

Once these molecules increase in size, they become trapped within the cortex.

This is why InLei® describes its tint as making a permanent change to the hair: the colour remains for the entire lifespan of that hair fibre, fading only as the hair naturally sheds.

InLei® tints are formulated to support this process while respecting brow integrity:

• Monoethanolamine (MEA) is used instead of ammonia to gently adjust pH and support penetration with less volatility and odour.

• Plant-derived waxes help deliver pigment evenly into the fibre.

• Argania spinosa (argan oil) supports lipid balance, helping to reduce dryness, brittleness, and surface roughness after chemical processing.

• The 1.5% developer provides sufficient oxidation to develop colour without aggressively degrading keratin.

This is also why InLei® tints must be mixed immediately before application. Oxidation must occur inside the hair. If tint is pre-mixed and left to stand, oxidation begins in the bowl. Colour molecules enlarge before entering the cortex, reducing penetration, vibrance, depth, and longevity.

Tinting is not colouring over hair.

It is building colour within it.

Step 3 – Brow Bomber 3

The lipid restoration phase: where structure is supported and surface integrity is rebuilt

Brow Bomber 3 is not designed to “fix damage.”

Its role is to stabilise, lubricate, and protect the hair fibre after chemical restructuring.

After Lift 1 and Lock 2, the brow hair has undergone controlled reduction and oxidation. Disulfide bonds have been broken and reformed, the keratin matrix has shifted, and the cuticle has been raised and re-contracted. Although the internal structure is now stabilised, the fibre’s lipid layer has been disrupted.

This lipid layer is essential.

It controls:

• flexibility

• light reflection

• moisture regulation

• resistance to brittleness

• and surface smoothness

Brow Bomber 3 is a pure, anhydrous oil-based formulation, designed specifically to replenish this lipid system without introducing unnecessary water, preservatives, or swelling agents.

Its blend of sweet almond oil, macadamia oil, argan oil, and sunflower oil delivers fatty acids that integrate into the hair’s surface and intercellular spaces, improving fibre lubrication, reducing friction between cuticle scales, and restoring pliability after chemical change.

Macadamia and argan oils are particularly rich in oleic and linoleic acids, which support hair softness, elasticity, and break resistance. These oils do not “repair” keratin bonds — instead, they optimise the environment around them, helping the restructured hair maintain flexibility and visual integrity over time.

Because Brow Bomber 3 contains no added water, it does not reswell the fibre. Instead, it creates a protective lipid veil that supports shine, smoothness, and barrier function.

At the skin level, calendula and chamomile extracts provide soothing, anti-inflammatory support, helping calm the peri-brow area after chemical processing.

Brow Bomber 3 does not change the shape of the brow.

It supports the hair that now holds that shape.

This is where chemical restructuring becomes long-term cosmetic quality.

Brow Bomber is not a trend-driven service. It is a controlled chemical process that reshapes, stabilises, colours, and supports brow hair at a structural level. Every phase — reduction, oxidation, tinting, and lipid restoration — plays a distinct role in determining not only how brows look on the day, but how they behave, feel, and grow over time. When these steps are understood, not just followed, the artist gains the ability to work with intention: adjusting technique, timing, and application based on real hair behaviour rather than habit. This is the foundation of the InLei® Method — education before assumption, science before shortcuts, and results built on understanding rather than chance.