Popular Edge Myths!

Myth - Obtuse edge angle has better edge retention

Some have also speculated that acute edges start out sharper but an obtuse edge lasts longer, and that reducing edge angles decreases the longevity of the cutting edge.

In reality, acute-angled edge stays considerably sharper and maintains this performance advantage for the duration of both the CATRA and our BESS-SET cutting tests across various mainstream and super-steel knives.

Take for example well-hardened felling axes - they are sharpened at 25° included and sharp enough to shave with.

Myth - Proper sharpness for a given cutting task

Common misconception is that sharpening a blade past a certain point is useless since the edge that is too sharp will dull fast, so there is some level of sharpness acceptable for particular cutting task.

Be confident that, no matter what task it is for, the knife benefits from the sharpest edge apex you are able to put, while the cutting task determines how much "meat" it needs behind the apex i.e. what the edge angle should be. The few exceptions I can think of is chopping through bones and tendons, and skinning a valuable fur where a duller knife is a precaution not to cut it through.

Fact is that for the best cutting performance, the edge should always be sharpened to the sharpest possible apex. Experiments in cutting tests have shown that the best cutting performance through the test have knives with the best initial sharpness.

Sharp apex does not predispose the edge to rolling - over-thinning the edge profile past the angle at which it deforms in cutting certain stuff does. Rolled cutting edges are a result of over-thinning the edge beyond the optimal angle required for the intended cutting task.

Even when the edge has rolled - try to visualize the rolled edge with your mental vision and see the sharp apex at the rolled end - the stuff it cuts wraps over the bend until it contacts the edge apex where it is severed; when the apex is sharp even the rolled edge cuts better. In other words, the sharper edge mitigates negatives of the edge rolling.

Myth - Coarse "toothy" edge cuts better

The micro-serrations" concept contributes to the confusion as people tend to mistakenly generalise properties of the serrated edge onto the microscopic level of a ragged coarse edge. The saw teeth and the edge apex ragged by coarse scratches are not the same.

A knife edge sharpened to rougher finishes will have larger scratches than a finely honed edge, and these scratches can be thought of as pre-existing flaws; the sub-surface damage is also more.