Why fourteen weighs less than one
The weight of a lash extension goes with the square of its diameter, roughly, because it is a cylinder. Halve the diameter and you quarter the weight. So a 0.07mm lash is about a fifth the weight of a 0.15mm one, and four of them together still come in under a single classic extension.
At 0.03mm the arithmetic goes further: those lashes are so fine that fourteen of them together sit inside the same weight budget. That is why mega volume exists at all and why it is safe on lashes that would not carry a heavy classic set.
What limits a fan is not weight, it is the base. Fourteen lashes have to be gathered into a point fine enough to bond to one natural lash without spreading down its length, and that is where the skill sits.
Hand-made against pre-made
Every fan in this studio is made at the chair, from a strip, in about four seconds, immediately before it goes on. That is the standard and it is the reason a volume set takes two and a half hours.
Pre-made fans come in a tray, bonded at the base with a small bead of glue or heat. They are much faster, they are not inherently dangerous, and they are heavier at the base and less able to be adjusted to the individual lash. A studio using them can do a volume set in ninety minutes, and some do it well.
How to tell: ask. Anybody who makes their own will say so instantly and probably show you. It is a fair question and not a rude one.
The wrap
A well-made fan wraps around the natural lash rather than sitting on top of it, which is what holds a volume set on for two full weeks. A fan that has been closed too tightly at the base becomes a spike and behaves exactly like a heavy classic lash, which is the most common failure in volume work.