13.1 Permanent Wave Chemistry & Hair Analysis

How a Permanent Wave Actually Works

Permanent-wave and relaxer chemistry and procedures belong to the current Chemical Services domain, and perm chemistry is the foundation. The exam expects you to explain the process, not just name products, so learn the mechanism.

Hair's strength and curl pattern come from side bonds that link the polypeptide chains of the keratin protein. There are three types:

• Hydrogen bonds — weak physical bonds broken by water or heat and re-formed as the hair dries (the basis of wet sets and thermal styling).
• Salt bonds — weak physical bonds affected by changes in pH.
• Disulfide bonds — strong chemical bonds formed between sulfur atoms of two cystine amino acids. Only a chemical service can break these, which is why perms and relaxers are called permanent.

A permanent wave takes place in two phases:

1. Physical phase — the hair is wrapped on rods. The size and shape of the rod determines the size and shape of the new curl.
2. Chemical phase — two reactions happen in sequence:
   • Reduction: the waving lotion, built on a thio compound, breaks the disulfide bonds. A hydrogen atom attaches to one half of each sulfur-sulfur link, so the bond can no longer hold the chain in its old position. The hair softens and can take the shape of the rod.
   • Oxidation (neutralization): after rinsing, the neutralizer — usually hydrogen peroxide — is applied. It removes the added hydrogen and rebuilds the disulfide bonds in their new positions around the rod, locking in the curl.

A classic exam trap: the neutralizer does NOT soften hair and the waving lotion does NOT harden it. Lotion breaks bonds (reduction, softening); neutralizer rebuilds bonds (oxidation, hardening/fixing). Keep reduction and oxidation straight and several perm questions answer themselves.

Waving Lotion Chemistries

Alkaline waves (cold waves) use ammonium thioglycolate (ATG) as the active ingredient at a pH of about 9.0-9.6. Because they process at room temperature using only the client's body heat, they are called cold waves. They process relatively quickly and produce a firm, strong curl — good for normal to resistant hair, but potentially too aggressive for fragile or porous hair.

Acid waves use glyceryl monothioglycolate (GMTG) as the main active ingredient and work at a lower pH, so the cuticle swells less and the process is slower and gentler.

• True acid waves have a pH of about 4.5-7.0 and require added heat to process.
• Acid-balanced waves fall in between, around pH 7.8-8.2, and process at room temperature.

You will also see perms classified by their heat source:

• Exothermic waves are self-heating: an additive mixed with the lotion creates a chemical reaction that releases heat.
• Endothermic waves are activated by an outside heat source, usually a hood-type dryer, and will not process properly without it.

Hair Analysis Before Perming

Every chemical service starts with analysis, and the exam tests the five factors by name:

• Texture — the diameter of the strand (coarse, medium, fine). Coarse/resistant hair may need an alkaline wave; fine or fragile hair needs a gentler acid wave.
• Porosity — the hair's ability to absorb liquid. Overly porous hair absorbs solution too fast and can overprocess; resistant (low-porosity) hair may need a stronger lotion or longer processing.
• Elasticity — the ability to stretch and return. Normal wet hair stretches about 50 percent; poor elasticity signals weak disulfide structure and high breakage risk.
• Density — hairs per square inch; it affects section and rod sizing, not chemistry.
• Previous chemical history — prior color, bleach, henna/metallic salts, relaxers, or perms. Metallic salts can react violently with peroxide, and overlapping chemistries can destroy the hair.

When analysis raises any doubt, perform a strand test: apply solution to a few strands, process, neutralize, and evaluate the curl and condition. Strand tests are mandatory on questionable hair — exam scenarios describing bleached, relaxed, or damaged hair almost always have strand test as the correct next step.

Finally, know the incompatibility rule: thio perms and hydroxide relaxers must never be used on the same hair. Their chemistries are antagonistic, and hair that has been relaxed with a hydroxide product cannot safely be permed. A client who wants curl back after hydroxide relaxing is a consultation, not a service booking.

Why this matters on the exam

Expect scenario stems like: a client with highlighted, porous hair requests a perm. The distractors offer stronger lotion or longer processing; the correct answer is the gentler acid wave — or declining until a strand test is done. If you can map hair condition to perm type using the table above, you will handle most of this content area.