Scientific Concepts and Infection Control
Core science you must know
Understand the basics of pH (0–14 scale, 7 neutral), the difference between acids and alkalis, and how solutions like shampoos and relaxers sit on the scale. Know the three states of matter, the difference between physical and chemical changes, and simple electrical safety ideas such as not using water near outlets. Learn the difference between disinfectants (kill most bacteria and some viruses on surfaces) and antiseptics (safe on skin), and know that sterilisation destroys all microorganisms.
Infection control essentials
Know the chain of infection and the difference between cleaning, disinfection and sterilisation. Understand standard precautions: handwashing, gloves, and proper handling of blood or body fluids. Know the difference between bacteria, viruses, fungi and parasites, and be able to name examples. Understand how pathogens spread in a salon (direct contact, contaminated tools, droplets, and airborne particles) and how to prevent it with proper tool sanitation, single-use items, and clean linens.
Traps to watch
Questions often swap disinfectant and antiseptic, or confuse sterilisation with disinfection. Another common trap is the difference between sanitation (reducing pathogens to a safe level) and disinfection (destroying most pathogens on surfaces). Watch for wording about porous vs nonporous tools, since the required method differs. Also watch for questions about when to wash hands (before and after every client, after removing gloves) and which items can be reused after cleaning.
Rule of thumb and worked example
Rule of thumb: if a tool touches blood or body fluids, it must be cleaned and then disinfected with an EPA-registered hospital-grade disinfectant, following the label's contact time. Example: a razor nicked a client. Clean visible debris, then immerse or wipe with the correct disinfectant for the full label contact time, and discard single-use blades.