Haircoloring Principles: Practice Questions & Explanations

A patch (predisposition) test is recommended before applying haircolors that can cause allergic reactions (such as many permanent colors containing certain dyes) to check whether the client is sensitive or allergic to the product. A small amount is applied to the skin (often behind the ear or inner elbow) in advance, and the area is checked for a reaction. If a reaction occurs, the service should not be performed. The patch test protects the client from a potentially serious allergic reaction and is an important safety step.

In haircoloring, the level system measures the lightness or darkness of a hair color, typically on a numbered scale from darkest to lightest (for example, low numbers for dark shades up to high numbers for the lightest blondes). Level describes depth only, separate from tone (the warmth or coolness of the color). Understanding level — and distinguishing it from tone — helps cosmetologists analyze natural color and formulate or choose target shades. The level concept is a standard part of haircoloring theory on the exam.

Tone refers to the warmth or coolness of a hair color — for example, golden, copper, and red are warm tones, while ash and blue-based shades are cool tones. Tone is distinct from level, which describes lightness or darkness. Both level and tone are needed to describe a color accurately and to formulate results. Understanding tone (and how complementary tones can neutralize unwanted ones) is part of color theory tested on the exam, though detailed formulation is learned through training and practice.

Permanent haircolor works mainly within the cortex of the hair. The product (typically with a developer) raises the cuticle so the color can penetrate into the cortex, where it develops and becomes trapped, producing long-lasting color. This is why permanent color is a chemical change and grows out rather than washing away quickly. Temporary and some semi-permanent colors deposit more on the surface/cuticle. Connecting where color works (the cortex) to the structure of the hair shaft is standard color theory on the exam.

If a patch (predisposition) test produces a positive reaction — such as redness, itching, burning, or swelling at the test site — the cosmetologist must not perform the haircolor service with that product, because the client is showing a sensitivity or allergy that could cause a serious reaction if the product were fully applied. The service should be declined and the client advised accordingly. Respecting a positive patch test is a critical client-safety rule, and the exam expects candidates to know never to proceed after one.

Developer, commonly hydrogen peroxide at various strengths (volumes), is mixed with permanent haircolor to activate and develop the color and, depending on its strength, to lift (lighten) the hair's natural pigment so the new color can deposit. Higher-volume developers lift more. Developer must be used at the strength and in the proportions the manufacturer specifies. Understanding the basic role of developer in permanent color — develop and lift — is part of color theory, while precise formulation is learned through training.

Demi-permanent and semi-permanent colors are generally less long-lasting than permanent color: they deposit color and fade gradually over a number of shampoos, and they typically do little or no lifting (lightening) of the natural pigment, since they use little or no developer (or a low-strength one). Permanent color, by contrast, can lift and lasts until it grows out. Knowing the broad differences among temporary, semi-, demi-, and permanent color (longevity and lift) is standard color theory, with specifics learned through training.

Color, and especially lightener (bleach), must be applied carefully and processed only for the time the manufacturer and strand testing indicate, because over-processing — particularly with strong lighteners — can seriously dry out, weaken, and break the hair. Lightening is one of the more damaging services when done carelessly. Monitoring, strand testing, and respecting timing protect the hair's integrity. The principle that more processing is not better, and that lighteners demand particular caution, is reinforced in the coloring content of the exam.