Short answer: weft hair extensions collect the hair along a continuous band rather than dividing it into many individual strands. The weft is then professionally attached to the natural base using the technique intended for the chosen system.
The word “weft” therefore mainly describes the construction of the extension. On its own, it does not tell you exactly how it will be installed: there are several professional techniques for attaching a weft to natural hair.
What is a weft?
It is a continuous line of hair joined along the upper edge. Compared with a strand-by-strand extension, it allows the material to be managed as a band and distributes volume across wider sections of the head.
The VELVET catalogue includes two useful examples of different constructions. VELVET Tailored Classic uses a machine-sewn weft, while VELVET Tailored Genius has a thinner, more flexible base designed to be cut and finished without the bulk of some traditional wefts.
Why does weft thickness matter?
The base is the part that needs to be integrated and concealed by the natural hair. A thinner construction can make discretion and layering easier, but it does not remove the need to choose position, quantity and attachment method correctly.
Even a technically thin weft can become visible if it is placed too high or in an area without enough coverage.
Can a weft be reused?
A weft in good condition can normally be removed and repositioned. The actual possibility depends on the condition of the hair, the structure of the weft and any cuts or modifications made during the previous application.
Reuse is explored here: Can hair extensions be reused?.
How many grams do you need with a weft?
There is no standard quantity that applies to every head. Natural density, the length to be blended and the construction of the weft all change the project. VELVET Tailored lines are offered in 100 g configurations, but this describes the product rather than a universal prescription for a full head.
To understand why weight should always be considered in context, see How many grams of hair extensions do you need?.
In summary
Weft extensions are built as continuous bands of hair. They can be very versatile, but the result depends on the quality of the weft and how it is positioned and attached. “Weft” describes the support structure; the professional design determines how that structure actually integrates with natural hair.