5.4 Matching Texture Products to Hair Type, Prior Chemistry & Smoothing Systems
Key Takeaways
- Hydroxide and thio chemistry are mutually incompatible, so a hydroxide relaxer must never be applied over thio-processed hair or the reverse — the strand is destroyed.
- Virginia devotes 135 curriculum hours and 60 minimum performances to permanent waving and chemical relaxing for all hair types, including textured hair.
- A retouch relaxer is applied only to new growth, and overlapping onto previously relaxed hair is the single most common cause of mid-shaft breakage.
- Curl reduction and keratin smoothing systems are not relaxers: they typically use aldehyde or amino-acid chemistry sealed with heat rather than breaking disulfide bonds permanently.
- Formaldehyde and formaldehyde-donor smoothing systems are an occupational inhalation hazard requiring genuine local exhaust under 18VAC41-20-270 C 7, not an open window.
5.4 Matching Texture Products to Hair Type, Prior Chemistry & Smoothing Systems
The NIC blueprint closes its chemical-services sub-topic with a requirement that is easy to skim and heavily tested: "understand the chemical products used for the various hair texture types." Selection, not application, is where most chemical texture disasters start.
Step 1: read the hair before you read the label
| Property | How to assess | What it changes |
|---|---|---|
| Curl pattern | Visual — straight, wavy, curly, coily; note that pattern often varies by zone on one head | Determines system type and, for perms, rod size and wrapping pattern |
| Texture (diameter) | Roll a single strand between fingers: coarse, medium, fine | Coarse resists and needs more processing; fine processes fast and damages fast |
| Density | Strands per square inch | Affects sectioning size and product quantity |
| Porosity | Slide fingers up the strand toward the scalp; rough = porous | High porosity absorbs fast and unevenly — reduce strength and watch timing |
| Elasticity | Stretch a wet strand: healthy hair stretches to about 50% and returns | Low elasticity contraindicates the service |
| Scalp condition | Examine before every hydroxide service | Abrasions, irritation or open lesions mean postpone |
| Chemical history | Ask, then verify with a strand test | Determines what may safely be layered |
Fine, porous, previously lightened hair and coarse, resistant, virgin hair sit at opposite ends of every one of these axes and cannot take the same formula.
Step 2: match the chemistry
| System | Active chemistry | Approximate pH | Best suited to | Cannot be layered with |
|---|---|---|---|---|
| Sodium hydroxide (lye) relaxer | Sodium hydroxide; lanthionisation | 12.5–13.5 | Coarse, resistant, virgin textured hair; maximum straightening | Any thio service; lightened or badly damaged hair |
| "No-lye" guanidine hydroxide relaxer | Calcium hydroxide activated by guanidine carbonate | ~13 | Sensitive scalps; still a hydroxide | Any thio service |
| Lithium hydroxide / potassium hydroxide relaxer | Hydroxide family | ~13 | Alternative no-mix hydroxide options | Any thio service |
| Thio relaxer | Ammonium thioglycolate, higher concentration than a perm | ~10 | Clients who may later want a thio perm; softer results | Any hydroxide service |
| Alkaline (cold wave) perm | Ammonium thioglycolate | 9.0–9.6 | Coarse, resistant, non-porous hair; firm curl | Hydroxide-relaxed hair |
| Acid-balanced / true acid perm | Glyceryl monothioglycolate | 7.8–8.2 | Fine, porous, colour-treated hair; softer curl | Hydroxide-relaxed hair |
| Curl reduction / keratin smoothing | Aldehyde or amino-acid chemistry sealed with heat | Acidic to near-neutral | Frizz control while retaining some curl | Layering over recent hydroxide work without a strand test |
The one rule you cannot break: hydroxide and thio are mutually destructive. Hydroxide relaxers permanently convert about a third of the disulfide bonds into lanthionine bonds by removing sulfur; a thio product applied over that hair attacks a structure that can no longer respond normally, and the reverse is equally destructive. Result: severe, often total breakage. When a client's history is unknown or self-reported, a strand test is mandatory, and where metallic home products are suspected, run the 1-20 metallic salt test first.
Step 3: virgin application versus retouch
Virgin relaxer application — the hair has never been chemically straightened.
- Section into four quadrants and apply protective base cream to the hairline, ears and nape (mandatory for a base relaxer; a "no-base" formula contains its own protective agent but the hairline is still protected).
- Begin in the most resistant area, usually the back, and apply ¼ to ½ inch away from the scalp — body heat accelerates processing at the scalp.
- Work in thin partings, applying to the mid-shaft and ends first, then returning to apply to the scalp area last.
- Smooth rather than comb. Time from the first application, not the last.
- Rinse thoroughly with warm water for the full manufacturer time, then use the acidic neutralising shampoo — hydroxide relaxers are neutralised by lowering pH, not by an oxidiser.
Retouch application — new growth only.
- Apply only to the new growth. The single greatest cause of mid-shaft breakage is overlapping onto previously relaxed hair, which re-processes hair that has no bonds left to give.
- Keep the product off the scalp until the final smoothing pass.
- Do not exceed the manufacturer's maximum processing time in pursuit of a straighter result.
- Consider a protective cream on the previously relaxed lengths as a physical barrier.
The Virginia practical exam requires a virgin hair relaxer (no base) application with coloured simulated product in 15 minutes, so the sectioning and application sequence is examined directly.
Step 4: understand what smoothing systems really are
"Keratin treatment," "Brazilian blowout," "curl reduction" and "smoothing system" are marketing categories, not a single chemistry. Most fall into one of two groups:
- Aldehyde-based systems (formaldehyde, or donors such as methylene glycol, glyoxylic acid derivatives, or DMDM hydantoin) — the product is applied, the hair is blown dry and then flat-ironed at high temperature, which drives the reaction and locks the hair into a smoothed configuration. Effects are semi-permanent, fading over weeks to months.
- Amino-acid or "keratin protein" systems — deposit hydrolysed protein and film-formers; largely a conditioning and smoothing effect rather than a bond-altering one.
Neither category is a relaxer. They do not permanently convert disulfide bonds the way a hydroxide relaxer does, and they generally do not deliver the same degree of straightening on tightly coiled hair.
Two safety points that carry real weight:
- Inhalation exposure is the hazard. Flat-ironing an aldehyde system releases vapour into the stylist's breathing zone repeatedly, all day. 18VAC41-20-270 C 7 requires the salon area to be sufficiently ventilated to exhaust hazardous or objectionable airborne chemicals — for these systems that means real local exhaust at the station, not a propped door. The SDS binder required in the immediate working area by 270 E 1 will state the exposure controls the manufacturer expects.
- Label claims are not always accurate. Products marketed as "formaldehyde-free" have repeatedly been found to release formaldehyde during the heat step. Read section 8 of the SDS and treat the product according to what it actually contains. Using a product in a manner the FDA disapproves is separately reachable under 18VAC41-20-270 F 5.
Step 5: aftercare and rebooking
- Wait at least 7 to 14 days between a chemical texture service and any other chemical service, and always strand test before the second one.
- Relaxer retouches are typically scheduled every 8 to 12 weeks, dictated by new growth, not the calendar.
- Recommend acid-balanced, protein-and-moisture-balanced home care; over-proteinising already-brittle relaxed hair causes its own breakage.
- Record every service. Chapter 5.3 covers the record card; the formula, strength, timing, result and any client-reported sensation should be captured so the next visit starts from data rather than memory.
A new client says she had a "keratin treatment" six months ago but is unsure what her stylist used before that. She wants a sodium hydroxide relaxer today. What is the correct action?
What is the most common cause of mid-shaft breakage in a relaxer retouch?
Which statement about aldehyde-based smoothing systems is accurate?