There is a significant difference in the quality of hair scissors by their material, heat treatment, and craftsmanship.
The visual inspection makes the difference in material and heat treatment quality challenging to distinguish. However, the craftsmanship can be easily singled out. Of the qualities the eye can inspect, the ride line is one of the most critical elements.
If the ride line is not made correctly, the scissors do not cut the hair or give a bad feeling. To make the best ride line, you must maintain your whetstone flat.
Otherwise, the surface becomes curved, not flat. The curved part makes the cutting power weak. Unfortunately, it is hard to check that subtle difference upon visual inspection. Therefore, flattening the whetstone is an essential process for sharpening.
I use whetstone and lapping film according to the condition of the shears. Most factories use whetstones, but I recommend sharpeners to use lapping films.
There are a variety of reasons. PSA-backed lapping films on metal blocks can be used to maintain a flattened surface at all times. Lapping films are also used in dry conditions, so it is 3 times faster and more accurate than the whetstone.
The cost is a little bit high for factory use, but it is more suitable for mobile sharpeners. Based on my experiences, my sharpening service with lapping films made most stylists happy; which eventually leads to more income to cover the expenses as more customers want my service.
Another reason lapping films are recommended is that whetstones create a mess as black powder-like materials rub off the stone and mix with the water when honing the blade. However, this mess makes the honing possible, making it inconvenient to use in a non-factory condition, like mobile sharpening.
Also, the whetstones must be soaked 10 minutes before usage.