Chemical Services
Chemistry basics
Chemical services change the hair’s cortex. Permanent color and lightener break and reform pigment; perms and relaxers break and rebuild disulfide bonds. pH matters: alkaline products swell the cuticle; acids close it. Developer (hydrogen peroxide) volume controls lift: roughly 10 volume for deposit only, 20 for 1–2 levels, 30 for 2–3, and 40 for 3–4, but always follow the manufacturer. The law of color: primary colors mix to make secondary colors; neutralizers cancel unwanted tones (blue cancels orange, violet cancels yellow, green cancels red).
Service categories
Permanent color, demi-permanent, semi-permanent, lightening, toning, highlighting, perming, relaxing, and straightening. Relaxers may be sodium hydroxide (lye) or guanidine/ammonium-based (no-lye); perms use ammonium thioglycolate or acid waves. Neutralizer stops the reaction and rebuilds bonds. A virgin relaxer is applied to new growth and previously untreated hair; a retouch is new growth only.
Safety and traps
Patch test before color or lightener per manufacturer; strand test for unknown history. Never apply lightener to the scalp unless the product is designed for it. Avoid overlapping relaxers; do not shampoo or heat-process outside directions. Metallic salts or box dyes can cause unpredictable reactions. Watch for allergic reaction, burns, and scalp abrasions.
Worked example: dark brown (level 3) to level 6 with permanent color. Approximate lift needed is 3 levels, so 30 volume is a reasonable starting point with a strand test; 40 volume would be riskier on fragile hair. Record the formula and timing.
Rule of thumb: if you cannot predict the outcome, strand test and take a smaller step.