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Serrations give the blade's cutting edge less contact area than a smooth blade, which increases the applied pressure at each point of contact, and the points of contact are at a sharper angle to the material being cut. This causes a cutting action that involves many small splits in the surface of the material being cut, which cumulatively serve to cut the material along the line of the blade. It can also give more structural integrity to a thinner blade, like how a fan fold is stronger than flat paper. This is because the zig-zag pattern resists force from different angles, called the "moments of area".
Cuts made with a serrated blade are typically less smooth and precise than cuts made with a smooth blade. Serrated blades can be more difficult to sharpen using a whetstone or rotary sharpener than a non-serrated, however, they can be easily sharpened with a diamond. Serrated blades tend to stay sharper longer than a similar straight edged blade. A serrated blade has a faster cut but a plain edge has a cleaner cut. Some prefer a serrated blade on a pocket knife.
Types of serration
- Tooth serration — Vertical serration along edge of blade
- Single edge serration — Serration on one side, the other remains flat
- Double edge serration — Serration on both sides
- Fan serration — Side-to-side serration without necessarily having a toothed edge
- Micro-serration — Serration much smaller than thickness of blade creating something like a fan pattern
- "The Serrated Bread Knife," Chronicle of Early American Industries, 2010 - article documenting the production of American serrated knives and saw-cut knives back as far as 1838.