Keratin, cysteine and nanoplastia are names used for different smoothing services. The right choice depends on the exact formula, your hair history and the finish you want.
A useful consultation starts with the product being proposed and what it can realistically do for your hair. Here are the details to compare before choosing a service.
Start with what hair is
The cuticle forms the hair fibre's protective outer surface; beneath it sits the cortex, which contributes much of the strand's strength and shape. A treatment may affect the surface, the internal structure or both, depending on its formula and application.
How hair reflects and scatters light contributes to its shine. Surface condition, colour and the alignment of strands all affect the result, so gloss alone cannot tell us how much processing a strand can tolerate. Research on hair lustre.
What all three have in common
These services aim to make hair smoother or easier to manage, and many combine a professional formula with heat. The service name alone does not identify the active ingredients, processing conditions or expected result.
Ask which product will be used and how its instructions apply to your hair. Claims such as โorganicโ, โnanoโ or โchemical-freeโ do not establish suitability. The useful details are the ingredient list, manufacturer instructions, hair assessment and aftercare plan.
Why the chemistry matters
Temporary styling and chemical straightening affect hair differently. Thioglycolate-based reshaping uses reduction and oxidation of disulphide bonds. Acid straightening can also change internal keratin structure; it cannot be explained simply as resetting weak bonds and sealing the surface. A finish that gradually fades does not prove that the fibre is unchanged. Thioglycolate research ยท Glyoxylic-acid research.
Keratin, or the Brazilian blowout
โKeratinโ and โBrazilianโ are broad service labels. Added keratin does not, by itself, tell you which ingredient produces the smoothing effect or how straight your hair will become. Formulas and protocols differ, so ask your stylist for the exact system and the result it is designed to achieve.
For any smoothing service, ask to see the ingredient list, application instructions and Safety Data Sheet. Some products contain or release formaldehyde during use; a category name cannot settle that question. FDA consumer guidance.
Cysteine
Treatments sold as cysteine or carbocysteine should be assessed by their actual formula. The name does not establish a standard pH, a universally gentler process or a predictable degree of straightening. Ask how the chosen product is expected to affect your curl pattern, what heat it requires and whether it suits your colour and treatment history. Research on a specified acid-straightening formula.
Nanoplastia
Nanoplastia also needs a product-specific explanation. The name alone does not establish particle size, deeper penetration, a fixed pH or one active ingredient. Ask your stylist to identify the system and explain its intended result using the manufacturer's directions.
The relevant comparison is how the proposed service suits your hair, including its current condition and previous processing. Avoid choosing solely from promises of stronger straightening or gentler chemistry attached to a category name.
So what actually differs
Use the consultation to compare these practical details:
| Service label | What to establish before choosing |
|---|---|
| Rebonding / permanent straightening | The exact reshaping system, suitability for previous processing and how future regrowth will be managed. |
| Keratin / Brazilian smoothing | The active formula, expected curl reduction, heat protocol and aftercare. |
| Cysteine / carbocysteine smoothing | The actual ingredients and processing conditions, plus the movement the chosen system is expected to retain. |
| Nanoplastia | The specific manufacturer's system, realistic straightening result and compatibility with the hair's condition. |
Ask how the finish is expected to change with washing and regrowth, and when a reassessment would be appropriate. These answers should refer to the product being used and your hair, rather than a promise that applies to every treatment with the same name.
How to actually choose
Use these three questions to guide your consultation.
How straight do you want it? Describe whether you want to retain your waves, reduce frizz or achieve a much straighter finish. Ask which suitable system can realistically deliver that result on your hair.
What has your hair already been through? Recently bleached, heavily highlighted or previously chemically straightened hair needs an honest assessment before any of these. A good stylist will sometimes tell you to wait. That is not them losing a sale; it is them not breaking your hair.
What will you do afterwards? Agree on a home-care routine you can maintain, following the instructions for the exact service.
Aftercare is not optional
Aftercare should follow the instructions for the treatment you received. Confirm when to wash, which cleanser and conditioner to use, and how to manage heat styling. If the manufacturer specifies a sulphate-free shampoo, follow that guidance. An ingredient claim on a shampoo does not, on its own, guarantee how long every smoothing result will last.
There is no single right product, and we are not going to pretend one brand covers every case. What suits you depends on which treatment you had, what your hair was like before it, and how hard your water is. We have gathered what our stylists actually recommend into one place โ Smoothing Aftercare โ across Kรฉrastase, LโOrรฉal Professionnel, QOD, K18 and De Fabulous.
Options to discuss with your stylist:
Where your service calls for sulphate-free cleansing, ask about the appropriate Kรฉrastase Discipline Bain Fluidรฉaliste formula or De Fabulous Reviver. Check the current product and your treatment's instructions.
If you received a QOD service, ask whether its matched aftercare is appropriate for your routine.
For straightened hair, LโOrรฉal Professionnel Xtenso Care offers a shampoo and mask routine. Your stylist can check the current products against your service instructions. Official Xtenso Care guidance.
If you use K18, ask your stylist where it belongs in your routine and follow its own application instructions.
The hard water problem
Minerals in wash water can accumulate in hair and affect how it feels and behaves. Water quality and the condition of the hair both matter. If a smoothing result changes sooner than expected, review the service, washing routine, styling and possible mineral build-up together; do not assume that calcium is the cause. Research on water hardness and hair.
Kรฉrastase Premiรจre is positioned by the brand as decalcifying care for damaged hair. LโOrรฉal Professionnel Metal DX targets metal-related hair concerns; its pre-shampoo is described as anti-porosity care that helps limit uptake of water containing metals. These are different product claims. Ask which, if either, fits the treatment you received before adding it to your aftercare. Kรฉrastase Premiรจre ยท Metal DX ยท Metal DX pre-shampoo.
Not sure which is right for you? Message us on WhatsApp to plan a visit to any Reflexions salon, and we will assess your hair before recommending anything. If the answer is that you should wait, we will tell you that too. See our hair services, browse Smoothing Aftercare, or ask our Beauty Advisor.