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1. On the pH scale, which value represents a neutral solution at room temperature?

The pH scale runs from 0 to 14. A value of 7 is neutral (the pH of pure water). Below 7 is acidic; above 7 is alkaline.

2. What is the approximate natural pH range of healthy hair and skin?

Healthy hair and skin sit in a slightly acidic range of about 4.5 to 5.5. This is often called the acid mantle and helps protect against bacteria and moisture loss.

3. A change from pH 5 to pH 7 represents how much of a change in hydrogen ion concentration?

The pH scale is logarithmic, so each whole number is a tenfold change. Two units (pH 5 to pH 7) means the solution is 10 x 10 = 100 times less acidic.

4. Sodium hydroxide hair relaxers (commonly called 'lye relaxers') typically have a pH of approximately:

Sodium hydroxide relaxers are very alkaline, with a pH of about 12 to 14. The high pH swells and breaks disulfide bonds quickly, so processing must be timed carefully to avoid scalp burns.

5. Which statement best describes a 'no-lye' relaxer compared to a 'lye' relaxer?

No-lye relaxers most commonly use guanidine hydroxide (mixed on site from calcium hydroxide and guanidine carbonate). They are generally less irritating to the scalp but can leave more mineral deposits, making hair feel drier.

6. Which chemical bond is broken when hair is permanently waved or relaxed?

Permanent waving and chemical relaxing both break and reform the disulfide bonds in keratin. Hydrogen and salt bonds are only temporarily broken by water or heat styling.

7. In a cold permanent wave, which chemical acts as the reducing agent that breaks disulfide bonds?

Cold waves use ammonium thioglycolate (ATG) as the waving lotion. It is a reducing agent that breaks disulfide bonds at room temperature. The neutralizer (usually hydrogen peroxide or sodium bromate) then re-forms the bonds in the new shape.

8. The neutralizer applied after the waving lotion in a permanent wave is an example of what type of chemical reaction?

The neutralizer (typically hydrogen peroxide) oxidizes the broken disulfide bonds, allowing them to re-form in the curled shape. Even though the product is called a 'neutralizer,' the chemistry is an oxidation reaction.

9. Which category of hair color coats the outside of the hair shaft and washes out in one to two shampoos?

Temporary colors (rinses, color sprays, gels) coat only the cuticle and rinse out in one to two shampoos. They do not penetrate the cortex.

10. Which type of hair color penetrates into the cortex and chemically lightens natural pigment while depositing new color?

Permanent (oxidative) color is mixed with a developer (hydrogen peroxide). It penetrates the cortex, lightens existing melanin, and deposits new color molecules that are too large to wash out.

11. A client wants to deposit color only, with no lift, and have it gradually fade over 4 to 6 weeks. Which product is most appropriate?

Demi-permanent (deposit-only) color uses a low-volume developer (typically 5 to 10 volume). It deposits color, gives slight conditioning, and fades gradually with no significant lift.

12. What does the 'volume' rating on hydrogen peroxide developer indicate?

Developer volume refers to the volume of oxygen gas released per volume of peroxide. 10 volume means each unit of peroxide releases 10 units of oxygen. Higher volume = more lift.

13. Which developer volume is typically used for deposit-only color and toners with no lift?

10 volume developer (about 3% hydrogen peroxide) deposits color and tones without lifting. 20 vol gives one to two levels of lift; 30 vol gives two to three; 40 vol gives the maximum lift used for high-lift color.

14. 20 volume developer is approximately what percentage of hydrogen peroxide by weight?

20 volume developer is approximately 6% hydrogen peroxide. 10 vol is about 3%, 30 vol about 9%, and 40 vol about 12%.

15. A formula calls for a 1:2 mixing ratio of color to developer. If you use 2 ounces of color, how much developer should you add?

A 1:2 ratio means two parts developer for every one part color. 2 oz color x 2 = 4 oz developer.

16. What is the primary cleansing ingredient in shampoo?

Shampoos clean using surfactants (surface-active agents). One end of the molecule attracts water (hydrophilic) and the other attracts oil and dirt (lipophilic), allowing soils to be rinsed away.

17. A 'pH-balanced' shampoo is formulated to a pH of approximately:

pH-balanced shampoos are formulated to roughly match the natural pH of hair and skin (about 4.5 to 5.5). This helps the cuticle lie flat and reduces dryness and irritation.

18. Which type of shampoo is best for removing mineral and product buildup before a chemical service?

Clarifying shampoos contain stronger surfactants or chelating agents that remove hard-water minerals, chlorine, and styling product residue. They are useful before chemical services but can be drying with frequent use.

19. Alpha hydroxy acids (AHAs) such as glycolic and lactic acid act primarily on the skin by:

AHAs are water-soluble acids that loosen the bonds between dead surface skin cells (corneocytes), promoting gentle exfoliation. They work on the surface of the stratum corneum, not in the dermis.

20. Salicylic acid (a beta hydroxy acid) is especially useful for which type of skin?

Salicylic acid (BHA) is oil-soluble, so it can penetrate through sebum into pores. This makes it useful for oily and acne-prone skin to clear clogged follicles.

21. Retinoids (vitamin A derivatives) are used in skin care primarily to:

Retinoids speed up cell turnover and stimulate collagen and elastin production, making them popular for anti-aging and acne treatment. They can cause dryness and increased sun sensitivity.

22. What does the 'SPF' number on a sunscreen primarily measure?

SPF (Sun Protection Factor) measures protection against UVB rays, which cause sunburn. For UVA protection (which causes aging), look for 'broad-spectrum' on the label.

23. Under Cal/OSHA's Hazard Communication Standard, a salon must keep a Safety Data Sheet (SDS) for:

8 CCR §5194 requires employers to maintain an SDS for each hazardous chemical present in the workplace and to make them readily accessible to employees during their shift.

24. How many sections does a Safety Data Sheet contain under the current Globally Harmonized System (GHS) format?

GHS-formatted SDSs have 16 standardized sections, ranging from product identification (Section 1) to other information (Section 16), including first aid, handling, and toxicology.

25. Methyl methacrylate (MMA) liquid monomer is:

Business and Professions Code §7315 prohibits the use of MMA liquid monomer on clients in California. Ethyl methacrylate (EMA) is the legal alternative for acrylic nail systems.

26. Hair with low porosity tends to:

Low-porosity hair has tightly packed cuticle scales that resist absorbing water and chemicals. It may require longer processing or a presoftener. High-porosity hair absorbs and releases chemicals quickly.

27. Before a permanent wave, a strand test is performed mainly to:

A strand test (also called a test curl) shows how the client's hair will respond to the wave solution so the stylist can choose the right product and time, preventing over- or under-processing.

28. Under California sanitation rules, salon chemical products should be stored:

16 CCR §979 requires products to be properly labeled and stored in clean, dry areas, separate from food, and in closed containers when not in use to avoid contamination or spills.

29. Leftover chemical color and developer should be disposed of by:

SDS Section 13 covers disposal. Used chemicals must be disposed of according to the manufacturer's directions and local hazardous-waste regulations, not into storm drains or open containers.

30. Which section of an SDS tells the cosmetologist what to do if the chemical is splashed in the eyes?

Section 4 (First-Aid Measures) of a GHS-formatted SDS lists the immediate steps to take for eye, skin, inhalation, and ingestion exposure.

31. After a chemical service that raises the hair's pH (such as relaxing or permanent color), an acidic 'normalizing' or finishing rinse is used to:

Acidic finishing rinses bring the hair back toward its natural pH (around 4.5 to 5.5). This helps the cuticle close, locks in color, and reduces frizz.