What is serration? In it's simplest form it is like having teeth on the blade of the
shears. This is usually done on the finger blade but can be on both blades of
shears specifically intended for cutting very course hair. The "teeth" trap the
hair so it cannot slid out allowing for sharper weight lines and faster cutting.
Often the shears will have a beveled edge and be specifically intended for use
cutting dry hair usually in a shear over comb technique used by barbers.
Some convex shears may also have some serration near the tip of one or even
both blades. This is most likely to be done for someone that does a lot of point
cutting. Putting the serration only on the tips allows the stylist to still be able
to do some slither, slide, or scoop cutting by opening the shear wide but,, this
can be awkward during detail cutting.
The down side of serration is that if it is course or on both blades, then the
shears feel "rough" during the cut and may require more hand strength to
close.
The serration I will do is about 5.5 "teeth" per millimeter. This means it will be
just visible to the naked eye and the shears will still feel smooth during the cut.