10.1 Product Ingredients and Purposes

10.1 Product Ingredients and Purposes

NIC Theory Domain 3, Chemistry of Nail Products, is about 10% of the scored written exam. That slice is not a brand-name quiz. It is whether you can say what an ingredient is for, how it behaves on a Washington nail plate, and why the wrong bottle in a Seattle dappen dish produces lifting, burns, or a product that never sets. WAC 308-20-080(4) already requires manicurist training in the safety of chemicals. Domain 3 adds the chemistry underneath those safety habits: adhesion, primers, monomers, polymers, initiators, solvents, and the film that becomes polish.

Adhesion versus cohesion

Two forces keep an enhancement on a finger, and NIC will treat them as different words.

Adhesion is attraction between unlike molecules or surfaces. Product-to-nail-plate is adhesion. Primer-to-keratin is adhesion. A gel overlay sticking to a properly prepared natural nail is adhesion. When adhesion fails, the enhancement lifts at the cuticle line, sidewall, or free edge even if the overlay is still one solid piece in your hand.

Cohesion is attraction between like molecules. Acrylic sticking to acrylic, gel sticking to gel of the same system, wrap resin locking fibers to themselves — that is cohesion. A well-polymerized enhancement can be internally cohesive (it does not crumble) and still fail if it never adhered to the plate.

Prep is mostly an adhesion problem. Mix ratio and cure are mostly cohesion and polymerization problems. A Tacoma client whose overlay pops off as a whole shell had cohesion success and adhesion failure. A brittle overlay that cracks down the center had a cohesion problem even if the perimeter still stuck. Adding more primer will not repair a crumbly dry bead, and extra powder will not repair oil left on the plate.

Dehydrators: oil and water off the plate

A dehydrator (nail prep) removes surface oils and residual moisture from the nail plate so adhesive products can contact keratin. Many dehydrators are alcohol-based. They are not glue. They do not polymerize. They do not replace primer. They make the plate a drier, cleaner surface so adhesion has a chance.

Put dehydrator on the plate after gentle surface buffing and before primer or base product, following the manufacturer. Do not flood it onto living eponychium. Do not apply cuticle oil and then wonder why the dehydrator failed — oil is the opposite job. In a Bellevue suite, if you oil the nails and immediately apply acrylic, you sabotaged adhesion with an emollient. Dehydrate, then prime, then product. Oil belongs at the end of the visit, on skin, not as a secret first step.

Primers: methacrylic acid versus acid-free

Primer is a bonding aid between plate and enhancement. Two families show up on every NIC-style roster.

Acid primer commonly contains methacrylic acid. It chemically prepares the plate, can create a microscopically more receptive surface, and can chemically burn living skin if it runs into the eponychium, lateral folds, or hyponychium. Use a tiny amount on the nail plate only. Never paint it around the proximal fold because a Kirkland client wanted extra stick. Acid primer is not a dehydrator. It is not EMA monomer. The sting on living skin is not proof that adhesion is working; it is a burn path Section 10.3 returns to.

Acid-free primer (often called non-acid primer) is a bonding agent without that methacrylic-acid etch. It is typically a dual-sided adhesive: one face toward keratin, one face toward the acrylic or gel. Acid-free does not mean harmless. It can still irritate. It still belongs on the plate, not on living skin. It still requires the SDS in the immediate working area under WAC 308-20-110(4)(b).

Match primer to the system the manufacturer wrote. Do not assume every gel needs methacrylic acid. Do not skip dehydrator because you used primer. They are different jobs: one cleans and dries the surface, the other helps unlike surfaces hold.

Monomers, polymers, and benzoyl peroxide

Liquid-and-powder acrylic is a two-part chemical system.

The monomer is the liquid. In professional systems the common liquid is ethyl methacrylate (EMA) — small molecules that can link into long chains. EMA is not the banned methyl methacrylate (MMA) 100% liquid monomer named in WAC 308-20-110(15). Section 10.3 covers why MMA is prohibited. For Domain 3, know this pairing: EMA liquid is the working monomer you were trained to use; the powder is not that liquid.

The polymer is the powder. Those beads are already polymerized (typically a methacrylate polymer). They are not just color. They are the solid scaffold the liquid wets. Pigment in a pink powder is a colorant riding on that scaffold. It does not replace the chemistry of the bead.

Nail textbooks often pair the words catalyst and initiator. The ingredient you must place correctly is benzoyl peroxide in the polymer powder. Benzoyl peroxide is the initiator that starts polymerization when monomer wets the powder. Some liquids also contain a catalyst (an amine accelerator) that helps that initiator decompose. Do not hunt for benzoyl peroxide in the EMA bottle; look in the powder. When the bead is mixed, initiator plus monomer produce chain growth: small EMA molecules link around the polymer beads and the mix hardens into a new solid. Without an initiator, you have wet slurry that does not become a serviceable nail. The initiator is not a pigment and not a dehydrator. Do not scoop powder from a contaminated, unlabeled jar and expect a predictable cure.

UV photoinitiators in gels

Gel systems are not air-dry polish. They contain acrylate or methacrylate oligomers and monomers plus photoinitiators. A photoinitiator absorbs energy from a UV or LED lamp of the correct wavelength and starts polymerization. If the lamp is the wrong spectrum, underpowered, dirty, or used for the wrong time, the photoinitiator does not finish its job. The gel can feel sticky, smear, or remain a sensitizing uncured film on skin.

Gels are not just thicker polish. Polish forms a film when solvent evaporates, a physical change taught in Section 10.2. Gel becomes a polymer when light triggers the photoinitiator, a chemical change. Keep lids closed. Do not treat leftover gel on a Bellevue client's eponychium as extra shine — uncured acrylate on living skin is a sensitization route. The lamp is part of the ingredient system. A ceiling fixture in Tacoma is not the photoinitiator's lamp.

Cyanoacrylate: tips, wraps, and many dip resins

Cyanoacrylate is the family behind nail glue, many wrap resins, and many powder-dip resins. It is an instant adhesive that polymerizes in the presence of moisture, including moisture on the plate and in the air. That is why glue can grab a tip in seconds, why it can bond skin to skin, and why a drop in the eye is an emergency, not a rinse-later joke.

Use cyanoacrylate to attach tips, to saturate silk, linen, or fiberglass wraps, and, in dip systems, as the resin that locks powder coats. It is not EMA monomer. It is not gel photoinitiator chemistry. Do not thin it with acetone and call it acrylic liquid. Do not pour it into a dappen as if it were EMA. Follow the SDS if skin is bonded; do not rip. A wrap fiber without resin is just fabric. Dip powder without the matching cyanoacrylate-type resin is just loose polymer dust.

Solvents: acetone versus non-acetone

A solvent dissolves or thins another substance. On a manicure table, solvents carry polish ingredients in the bottle and later take the film back off.

Acetone is a fast, flammable solvent that removes nitrocellulose polish films and is the usual soak-off solvent for many acrylics, wraps, and soft gels. Keep it in a closed, labeled container, away from ignition, per WAC 308-20-110(4)(c). Acetone is not a dehydrator you casually substitute for manufacturer prep, and it is not an air freshener.

Non-acetone removers often use other esters such as ethyl acetate. They are typically slower on polish and gentler on some enhancement surfaces, which is why a client with a wrap or certain overlays may be told to use non-acetone on the polish only so the overlay is not softened with every home removal. Non-acetone is not safe acetone. It is still a solvent. It still needs a label and an SDS. It will not magically soak a hard gel the way acetone soaks a wrap.

Do not soak living skin as if the eponychium were product. Do not leave an open acetone bowl beside a space heater. Solvent choice is an ingredient-purpose question: fast strip versus gentler polish removal around an enhancement that is supposed to stay on.

Plasticizers, pigments, and film formers

Nail polish is a solution that becomes a film.

A film former — conceptually nitrocellulose in many lacquers — is the ingredient that remains as the hard, glossy or matte coating after the solvent evaporates. Without a film former you have colored solvent that never becomes a coat. Nitrocellulose is not a gel photoinitiator. It does not need a lamp. It needs the solvent to leave.

A plasticizer keeps that film flexible. A film that is only hard will crack when the natural nail flexes. Plasticizers are why polish can bend a little instead of shattering at the free edge. Historically dibutyl phthalate (DBP) was a common plasticizer; Section 10.3 treats it as part of the toxic-trio discussion. Modern formulas may use other plasticizers. The job is flexibility, not hue and not disinfection.

Pigments and colorants provide hue. They are not the film. A heavily pigmented polish still needs film former and solvent. In acrylic and gel, pigments tint the polymer; they do not replace benzoyl peroxide or a photoinitiator. White pigment is not primer. Glitter is not an initiator.

Cuticle oils are emollients

Cuticle oil is an emollient (and often an occlusive blend of oils) used to soften and condition living skin and remaining cuticle. That is aftercare and skin comfort, not adhesion chemistry. Oil on the plate before an enhancement is contamination. Oil after polish or after a finished, sealed enhancement is client care.

Do not use oil as primer. Do not use oil as dehydrator. Do not mix a drop into monomer for healthy nails. In a Spokane finish, oil the folds and the skin, not the unsealed underside of a lifting overlay. Emollient means it leaves a lubricating, softening film. That is the opposite of what a dehydrator is for.

Ingredient map for a Washington table

Salon scenario — Seattle adhesion complaint. A Seattle fill lifts at day four. The overlay is still one piece, so cohesion held. The plate had oil on it, so adhesion never had a clean surface. Dehydrate; do not just flood more primer.

Salon scenario — Tacoma primer burn. A Tacoma student floods methacrylic acid primer into the proximal fold. That is living eponychium, not plate. Stop, follow SDS first aid, and do not continue product on burned tissue.

Salon scenario — Olympia glue versus liquid. An Olympia receptionist grabs cyanoacrylate to thin the acrylic. Glue is not EMA. The set will not behave like liquid-and-powder chemistry, and skin can bond in seconds.

Salon scenario — Vancouver, WA polish science. A client asks why polish dries in air but gel needs a lamp. Polish: solvent evaporates, a nitrocellulose-type film remains. Gel: a photoinitiator needs the correct lamp. Different ingredients, different jobs.

Domain 3 will name the job, not the brand. If you can say adhesion versus cohesion, dehydrator versus primer, EMA versus polymer powder, benzoyl peroxide versus photoinitiator, cyanoacrylate, acetone versus non-acetone, film former, plasticizer, pigment, and emollient oil, you can answer purpose-and-effect items and still keep Washington product rules in view.