Nails Ch5 – Química de las uñas


  • A force of nature that makes two surfaces stick together.
  • Results when the molecules on one surface are attracted to the molecules on another surface.
  • Oils, waxes, and soil will contaminate a surface and block adhesion.


  • A chemical that causes two surfaces to stick together.
  • Adhesives allow incompatible surfaces to be joined.
  • There are many types of adhesives.
  • Different adhesives are compatible with different surfaces.

Nail Primer

  • A substance that improves adhesion.
  • There are three basic types: acid-based, nonacid, and acid-free.
  • Some create physical bonds between the nail plate and the nail enhancement.
  • Newer types chemically bond the enhancement and the nail plate.

Acid-based Nail Primers

  • Common misconception: nail primers eat or etch the nail.
  • They must be used with caution as some are very corrosive to soft tissue and eyes.
  • They must never touch the skin.
  • Must be kept in containers with child-resistant caps.
  • Gloves and safety glasses are recommended when these products are in use.
  • Can burn the nail bed tissue if nail plate is improperly filed.
  • Use sparingly — one very thin coat is enough for most clients.
  • If you find you rely on two coats to prevent lifting, check your nail preparation and application procedure for problems.

Non acid or Acid-free — not all primers are corrosive to skin.

  • Do not contain methacrylic acid.
  • Nonacid primers may contain other types of acidic substances.
  • Acid-free primers contain no acids and have a neutral pH.
  • Must be used with caution and skin contact must be avoided.
  • Prolonged and repeated contact can lead to an allergic reaction.

Avoid Over-Filing

  • Myth: nail enhancements and tips do not stick unless you rough up the nail.
  • Avoid using heavy-grit abrasives, heavy-handed filing (too much downward pressure), and improper use of electric files.
  • Thinner nail plates create a weaker foundation for nail enhancements.
  • Excessively roughing up the nail plate may cause:
  • The nail plate to lift and separate from the nail bed
  • Clients to be more susceptible to infections
  • Nail enhancement service breakdown and lifting
  • Breaking
  • Free-edge chipping
  • Free-edge product separation or curling
  • Allergic reactions Painful friction burns to soft tissue of nail bed

Monomers and Polymers

  • Durable and long-lasting coatings or nail enhancements are all created by chemical reactions.
  • All monomer liquid and polymer powder nail enhancements, UV gels, wraps, and adhesives are examples of chemical reactions.
  • The molecules in the product join in extremely long chains, with each chain containing millions of molecules.


  • Gigantic chains of molecules.
  • Polymers can be liquids, but are usually solid.
  • Polymerization: chemical reaction that makes polymers.
  • Terms cure, curing, or hardening are used.
  • Types: Teflon, nylon, hair, wood, proteins.
  • Nail plates are made of many proteins, including keratin, so nail plates and hair are made from polymers.


  • Individual molecules that join to make the polymer.
  • Example: amino acids (monomers) join together to make keratin (polymer).

Understanding Polymerization

  • Each type of nail product is made from a different but closely related monomer.
  • Special ingredient called an initiator triggers polymerization of the monomers.

Process of polymerization:

  • Initiator molecules carry extra energy and gives monomers that energy.
  • Monomer molecule attaches to another monomer to pass the energy along.
  • Second monomer does the same as the first.
  • Reaction continues and the chain of monomers gets longer.
  • Monomer chains become tangled; this is why the product starts to thicken.
  • Chains are too long and crowded to freely move; surface is hard enough to file.
  • It is several days before the chains reach ultimate lengths, which explains why all nail enhancements become stronger during the first 48 hours.

Initiators get the extra energy they pass on from either heat or light.

Thermal initiators: heat of the room or hand; used by liquid and powder systems

Photo initiators: exposed to UV; used by UV curing products

Catalyst: Speeds up a chemical reaction; makes initiators work more efficiently or by helping chemical reactions happen more easily.

  • Found in every type of nail enhancement product; the reason why they harden quickly.

Oligomer: Short chain of monomers; growth halted before it became a polymer.

  • Useful as they can be joined quickly and easily into long chains to create polymers.
  • Ingredients in UV gels and are what give the gels their sticky consistency.

Simple Polymer Chains: a long chain of monomers attached head to tail.

  • Wraps and tip adhesives form this type of polymer.
  • Tangled chains are easily unraveled by solvents.
  • Can also be unraveled by force.
  • Easily damaged by sharp impacts or heavy stresses.
  • Dyes and stains can also get lodged between the tangled chains— nail polishes, marker ink, foods, etc.

Cross-Linker: a monomer that joins different polymer chains together.

  • Used by UV gels and monomer liquid and polymer powder nail enhancements.
  • Create strong net-like polymers resulting in a single three-dimensional structure of great strength and flexibility known as a nail enhancement.
  • More resistant to staining.
  • More resistant to solvents, including water and acetone.