Polished plain edge vs serrated edge which will push cut better in real world use?

M

MichaelMyers

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Dec 10, 2015
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The general consensus is the plain edge with high polish edge will have the highest push cutting sharpness followed by coarse edge then the serrated edge. However I have recently cut myself by accident on the thumb by applying the mildest of pressure on the serrated edge of my leatherman wingman. I wasn't drawing my thumb across the blade. It was just pushing. The cut was quite bad. Even with considerably more pressure I was not able to cut myself in this manner on ANY of my plain edge knives even the highly polished ones. I have to slide my fingers on the edge to get them to cut a little into the top skin layer. Where the plain polish edge did better was push cutting thin paper and shaving arm hair.
Next i tested by pressing the blade edges down on the flat surface of a piece of cardboard. The serrated edge was able to bite into the cardboard with less pressure. Test on rope straight push cut no slice. Serrated outperforms the plain edge again. So my experience is on the common sharpness tests: paper edge and shaving, plain polish edge push cuts better. On other tests: flesh, rope, flats of cardboard. The serrated edge push cuts better. Hmm anyone has a similar experience?
 
Yes, many times. A properly sharpened and well designed serrated edge has many very sharp points. A point penetrates easier than a line on a straight edge because it concentrates pressure in a single spot to begin the cut.
 
Cobalt said:
Yes, many times. A properly sharpened and well designed serrated edge has many very sharp points. A point penetrates easier than a line on a straight edge because it concentrates pressure in a single spot to begin the cut.
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Your point vs line theory makes a lot of sense. I think you have a point there.
 
Cobalt is correct.

For the same reasons a coarsely sharpened plain edge will perform better than a finely polished plain edge. The more tooth in the edge the better it will cut.
 
By design serrated knives cut by pull cuts, aka slicing. The serrations pull the material to be cut into the serrated pocket. If you try to push cut on a serrated point, it will slip into the pocket to cut, thus not a push cut.
 
If the serrations are sharp enough (i.e.Spyderco sharp) each scallop and valley acts as a very sharp plain edge blade, sometimes by drawing the cutting media towards the "peaks" and slicing it just before it touches the peaks, at the limit of the "valleys".

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They have to be very sharp to do this, though, otherwise they'll just grab and rip
 
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