Blade Coating vs Performance?

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trailside22

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Sep 8, 2005
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I have been interested in how blade coatings effect cutting performance. I know that many makers add a coating to help protect the blade and others add it because it is "tacticool." Some knife makers will not add a blade coating. I am interested in your thoughts on this.
 
I'd think it'd depend on the coating....Of course, if you're just cutting open a package, it probably won't make any difference, only when you've got to slice through something all the way so that the black coating comes in contact. It seems pretty rough, Benchmade's coatings at least, so it might have resistance...but...it comes off so easily it might just get ripped off by the cardboard anyway. Tini is really smooth, in my experience, and also much tougher anyway...so less resistance.

But I rather doubt it's a noticeable impact, either way. Blade thickness seems to be the magic trick to cutting through materials.
 
I don't think it's a big deal either way, but some of the newer coatings like DLC seem harmless enough. A good polished blade, kept reasonably clean, doesn't need a coating.
 
trailside22 said:
I have been interested in how blade coatings effect cutting performance.
Click to expand...

Generally the friction from even the rougher coatings doesn't have a significant influence on the force which opposes a blade in cutting. The main forces are those which oppose the very edge and the wedging forces against the blade body. Most of the rougher coatings also wear smooth quite quickly in use anyway. There have been actual studies on this concerning the forces on blades cutting wood and the influence of friction, Lee cites them in his book on sharpening.

Note as well that most coatings are far more even than the splotchy patina that develops instantly on low alloy tools steels like L6. These steels can rust so quickly that you can cut acidic foods and watch them discolor the food and rust right in front of your eyes during the cutting. You don't need to let them sit in the juices, it happens as the food is being prepared. This is a shot of a Roselli Hunter after cutting just one onion :

roselli_onion.jpg


You can already see visible rust forming on the blade. The effect this has on the edge sharpness is far more of a detriment to the cutting ability than even the roughest coating. Most of the tool steels have far greater corrosion resistance than this, but some of the low alloy ones like O1 will rust extremely fast, pretty much instantly, which is why some makers like McClung are so adamant about coatings.

-Cliff
 
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