There are three main methods of hair extensions:clip-ins, weld-ons and strips to stick on. The duration of the installation, the price and the outfit vary according to each process. Only requirement:your hair must be at least 10 centimeters long. Before deciding, ask yourself the right questions. What hair length do you want? Do you want a lasting change or a one day look?
Clip-in extensions
If you like to change your hairstyle every day, without wasting time or breaking your budget, clip-in extensions are for you. No need to go to the hairdresser, you can do it yourself! Simply fix the locks in your hair with clips or barrettes. In addition to being economical,this express method does not damage the hair . As quick to attach as they are to detach, clip-in extensions allow you to test all kinds of looks without taking any risks.
Welded extensions
This is the solution for those who want a lasting change or who wish to let their hair grow. Each extension is tied, strand to strand, by a plastic or keratin-based attachment point. Installation therefore takes a long time. Depending on the quality of the extensions, their maintenance and the growth of the natural hair, the locks will have to be repositioned every four months or so. Everything is rather expensive , but the results are impressive and long-lasting.
For this method, a distinction is made between hot and cold laying. The hairdresser can attach extensions using ultrasound, compressed air or laser, all common and good quality options that seriously boost the volume of the hair. Alternatively, metal or plastic micro-cylinders can be slid over the strand, then compressed onto the natural hair using special pliers.
Another cold laying process:weaving . Extensions of varying thicknesses are braided or sewn onto the natural strands. A classic method but one that requires a lot of time.
Glue-on extensions 
These are wicks glued or sewn on an adhesive strip. The installation is a little faster than for the welded extensions, since several locks are glued at the same time instead of fixing them one by one on the natural locks.
The advantage:you can add more hair in one step.
The downside:these extensions last less than soldered wicks. In any case, you must have enough hair to hide the extensions. If a whole swath of hair comes off, it shows right away, unlike the absence of just one small strand.
These strips of wicks are fixed with a silicone glue. The installation is fast , but you have to use solvent to take them off. 
