Skate blades are not flat. They are shaped in two directions, and those shapes decide how a player accelerates, turns and stops.
The curve along the blade
Viewed from the side, a blade is curved rather than straight, so only a portion of it contacts the ice at any moment.
A tighter curve puts less blade on the ice, which makes turning easier and pivoting quicker but reduces stability at speed.
A flatter profile keeps more blade in contact, giving better glide and straight-line stability at the cost of agility in tight spaces.
The hollow across the blade
Sharpening grinds a concave channel across the blade's width, leaving two edges that bite into the ice rather than a single flat surface.
A deeper hollow produces sharper edges that grip harder, allowing aggressive turns but also creating more friction and slowing the glide.
A shallower hollow slides more freely and is less tiring over a long shift, but it gives up bite when a player tries to change direction sharply.
Why players choose differently
A defender who pivots constantly and needs to stop hard tends toward a deeper hollow and a shorter contact area than a forward who skates in straight lines.
Body weight enters the calculation, since a heavier player presses the edge into the ice more firmly and can use a shallower hollow to the same effect.
Ice conditions matter too, and players often adjust their preference between a cold, hard sheet and a softer one later in a game.
What sharpening actually does
Edges dull through ordinary use, and a rounded edge slips where a sharp one would grip, which shows up first in a player's ability to stop.
Sharpening restores the hollow and the edges but removes steel, so a blade has a finite life measured in sharpenings rather than in games.
Players are highly sensitive to the result, and many will change skates mid-game if the edges feel wrong rather than continue on a blade they do not trust.
Why the setup is guarded
The combination of profile, hollow and blade mounting position is specific to each player and takes a long time to settle on.
Equipment staff record those specifications precisely so that a replacement blade can be prepared identically rather than approximated.
A skater whose blades feel unfamiliar loses confidence in his edges, and that hesitation shows up in the moments where the sport is decided.
