Chemical Services
Chemical Services
This domain tests haircolor, permanent waving, chemical relaxing, and keratin smoothing. Expect safety sequencing, patch and strand tests, product chemistry, and the difference between rebuilding disulfide bonds and breaking them.
Haircolor
Temporary color coats; semipermanent color deposits; permanent color lifts and deposits through an alkaline agent and developer. Developer volume controls lift: 10 volume deposits, 20 lifts about one level, 30 lifts more, and 40 is for high-lift. Aniline-derivative color requires a patch test 24 to 48 hours before first use. A strand test predicts timing on resistant or porous hair. Gray coverage needs enough pigment and adequate processing.
Waves and relaxers
Permanent waving uses thio or another reducing agent to break disulfide bonds, then neutralizer to rebuild them. Wrap tension and processing time control curl. Chemical relaxers use sodium hydroxide (lye) or no-lye agents at high pH to straighten; they require scalp protection, and a retouch applies product to new growth only. Neutralizing shampoo lowers pH and stops the relaxer.
Keratin and sequencing
Keratin smoothing products vary; some contain formaldehyde or release formaldehyde, so ventilation and label instructions matter. Do not perform a relaxer and a color service on the same day without following manufacturer and safety guidance.
Worked example
A client with resistant gray wants full coverage. A patch test is done, a strand test shows 30 minutes at 20 volume gives coverage without over-lifting, and the formula is applied to resistant areas first.
Traps
Overlapping relaxer onto previously relaxed hair; skipping neutralizer; using 40 volume when 20 is enough; coloring over a fresh relaxer too soon.