Short answer: the main difference between the methods is the heat and the way the strand is held. Keratin is melted with a heated tool at around 160 to 200°C; tape-in extensions are applied without heat but form a wide strip; micro rings use no adhesive but clamp the strand. UV bonding combines a small bond, cold application and water resistance once the adhesive has cured. Each method has its place, depending on the hair and the result wanted.
When a client sits in the chair and says “I want extensions, but I don’t want to damage my hair”, the conversation always ends up at the same question: which method? Four methods are commonly used in salons, and each has its merits. Let’s describe them in turn.
The four most widely used methods
Keratin (hot fusion)
This is the classic method. Each strand carries a small keratin tip at its end, which is melted with a heated tool around a section of the client’s own hair. The finish is very natural and the hold is good, but the section it is attached to receives around 160 to 200°C at every application. Over time, this repeated heat can break the fibre’s bonds, lift the cuticle and weaken the hair right at the root, where it hurts most.
Tape-in extensions
These are thin strips carrying an adhesive, sandwiched around the client’s hair. They go on quickly and without heat. They are wide, however: on fine hair or along the parting they can be spotted, and they do not always allow high updos.
Micro rings and nano rings
A section of hair is threaded through a tiny metal ring, which is then clamped with pliers. There is no adhesive and no heat, but the pressure and weight are concentrated at a single point. If the ring is too tight or the section too fine, breakage from tension is possible.
UV light bonding
A drop of clear UV adhesive joins the extension to the client’s section of hair, then cures under 395 nm ultraviolet light in 6 to 8 seconds per side. The bond is small, flat and flexible, and moves with the hair. We cover it in detail in UV light hair extensions: how they work, application and aftercare.
Quick comparison
| UV light | Keratin | Tape-in | Micro rings | |
|---|---|---|---|---|
| Heat during application | No | Yes, around 160 to 200°C | No | No |
| Bond size | Very small and clear | Small | Wide strip | Ring can be felt to the touch |
| Water resistance | Once cured; best to avoid getting it wet for 3 days | Good | Usually a 24 to 48 hour wait | Good |
| Time before maintenance | Up to 2 months | 2 to 4 months | 6 to 8 weeks | 6 to 10 weeks |
| Time for a full head | Under 2 hours | 3 to 4 hours | 1 to 2 hours | 2 to 3 hours |
| Fine hair | Small, flat bond | Apply with care | The strip may show | Risk of tension |
| Removal | Removal solution + gentle, controlled heat | Solvent + pliers | Solvent | Opening the ring |
Times and durations are indicative. They depend heavily on the hair type, home care and the professional’s skill.
So, do extensions damage the hair?
What damages hair is not so much wearing extensions as three very specific factors:
- Repeated heat at the same spot on the root, application after application.
- Tension: too much extension weight for the section carrying it, or bonds stuck to the scalp.
- Rough removal, pulling on a bond that has not yet let go.
UV bonding removes the first factor, since application is cold. The other two depend on technique: that is why the EHE LIGHT™ protocol calls for 0.5 to 1 g per bond, a distance of 1 to 1.5 cm from the scalp and a removal where the bond is never forced. It is all explained in the application guide.
What about the safety of the UV light and the adhesive?
A perfectly fair question. Let’s take it point by point.
The light. The device works at 395 nm, in the same UV-A band used to cure gel nail polish, and it includes a protective screen that limits exposure for the client and the professional. Each pass also lasts only a few seconds and is made within 1 cm of the bond, not on the skin.
The adhesive. Resins that cure under light contain acrylates. In liquid form, their molecules can sensitise the skin; once cured, they form a large polymer. That is why the professional protocol insists on three points: wear gloves, apply bonds that do not touch the skin and cure every bond completely.
An unbranded kit used at home, without gloves and without a protocol, does not offer the same conditions as a professional system applied according to a protocol.
If a client has a known allergy to acrylates (for example because of gel nails), they should say so before the application. In that case UV bonding is not suitable.
Which one should you choose?
- Fine or low-density hair: UV light, with a minimal bond and no heat. We explain this in extensions for fine hair.
- You want high updos and ponytails: UV light or keratin, which hide better than tape-in strips.
- You are coming from keratin and your roots are weakened: cold application is a logical option. You can switch from one method to the other in the same appointment after a proper removal.
- You want the lowest price in the short term: tape-in extensions. Bear in mind that, in the long term, maintenance appointments add up. We go through the cost factors in the price of a UV hair extension application.
If your salon still works with keratin pliers, find out what UV light changes.
Benefits for professionalsFrequently asked questions
Which method best limits the risk of damaging the hair?
It depends less on the method than on the application. Among methods applied section by section, UV bonding is distinctive in using no heat. Whatever the method, the risk depends mostly on the weight per section, the distance from the scalp and a removal without pulling.
Keratin or UV light: which should I choose?
Keratin lasts a little longer between maintenance appointments, but it is applied with a heated tool at 160 to 200°C. UV light uses no heat, the bond is smaller, it withstands water once the adhesive has cured and a full head can be done in under 2 hours.
Are UV light extensions safe?
When applied by a professional following the protocol, with a 395 nm device, protective screen and CE certification, gloves and bonds that do not touch the skin. They are not suitable for anyone with a known allergy to acrylates.
Can I switch from keratin to UV extensions?
Yes. The keratin extensions are removed, the hair is washed and thoroughly dried, then the UV extensions are applied in the same appointment.
Are UV extensions reusable?
Remy hair is. At each maintenance appointment the strand is removed, cleaned and bonded again with fresh adhesive.
