Cardboard, mortal enemy of sharp knives

S

sircantaloupe

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Jan 29, 2009
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It's likely you've had the experience of losing that shaving sharpness from your freshly sharpened knife with just a pass or two through cardboard. I know I have. But my selection of knives is limited. So I ask, what knife (and what steel) have you found to stand up to the abrasive pain in the butt that is cardboard? Myself, it's my RAT-1 in AUS-8.
 
Nothing, really. I don't think there is a knife that will remain shaving-sharp after a few cuts of cardboard.

I think the best thing against cardboard is thin blade geometry. My VG-10 Spyderco Stretch continues cutting longer than my ZDP-189 Delica due to, I believe, the thinner blade of the Stretch (& FFG vs. saber grind).
 
My ZDP189, SR-101, CPMD2, S30V, serrated H1, VG10 or 1095 when given a thin edge and properly heat treated will do what you describe. With my CPMD2 Military I've cut over two hundred feet of cardboard and had it still take arm hairs off. I'm sure it could of kept going, but I was out of cardboard.

Cardboard is pretty abrasive, and with any steel if you cut enough you will lose shaving sharpness no matter what.
 
I agree with Vivi.

You should note that some people actually strop with cardboard. That tells you just how abrasive the material really is.
 
Vivi mirrows my experience with steels & cardboard. as i've aged cardboard has gotten more tedious since some knives cut past 10 minutes on cardboard before they quit shaving.i believe the adhesives in boxes wear the edges more than the paper itself.
 
Depends more on the cardboard than the steel...at least in my experience.

Some cardboards are really "dirty" while others (particularly those for food packaging) are a lot "cleaner". Perhaps you are taking a good knife/steel and dulling it in a worst case scenario. If shaving sharp is really important to you, carry two knives and use only one for cardboard.

By "dirty" I mean that they are recycled and may contain particles of wood, metal, plastic, or other materials that are quite abrasive.
 
Vivi said:
My ZDP189, SR-101, CPMD2, S30V, serrated H1, VG10 or 1095 when given a thin edge and properly heat treated will do what you describe. With my CPMD2 Military I've cut over two hundred feet of cardboard and had it still take arm hairs off. I'm sure it could of kept going, but I was out of cardboard.

Cardboard is pretty abrasive, and with any steel if you cut enough you will lose shaving sharpness no matter what.
Click to expand...

My thoughts exactly. Personally I'd pick a small thin blade in hard CPMD2 and go to town. It won't be able to whittle hair, but it'll keep cutting cardboard (almost) forever.
 
I leave cardboard to the utility knife (aka the box cutter). I always have one of those hand as I find that to be just as hand EDC as a conventional knife.
 
Some cardboard is a lot more abrasive than others. I'd imagine that Cold Steel picks their cardboard carefully. ;)
 
Agreed cardboard is tough stuff, but if you really want to see what a blade will do try cutting through carpeting.

The jute backing will eat a knife up!!
 
Spyderco VG10 seems to hold up pretty well for me. I haven't tried ZDP-189 yet. For me AUS8 is the exact opposite. I have some kershaws in AUS8 that seem to go dull if I just hold them close to cardboard. In theory M4 should be the king of cardboard, although I again have no first hand experience with it...
 
After realigning the grinds on my knives with my Edgepro I can definitely go thru more cardboard before seeing the dull spots. The best against cardboard that I've used is my D2 Spyderco Paramilitary.
 
1st hand experience: M2 (default BM710HS).
After cutting a few (2-4?) meters of cardboard the edge still shaves the hair on my forearm and my legs. If the hairs are flying away before cutting the cardboard it usually gets that ''dull'' that it just shaves with some pressure but after that it holds its edge.

s_f
 
Phillip Dobson said:
My thoughts exactly. Personally I'd pick a small thin blade in hard CPMD2 and go to town. It won't be able to whittle hair, but it'll keep cutting cardboard (almost) forever.
Click to expand...

This is what I'm going for more than anything. Not shaving sharp but effective cutting sharp in the long term.
 
My S90V Military holds up well.

IME, AUS-8 is very easy to sharpen, but not very abrasion resistant.

I've also found that slicing a short, thin, piece of cardboard will take off a burr in the higher end steels without dulling it.
 
Two things to keep in mind when cutting cardboard that will minimize dulling and the required force to cut the media...cut with the grain, and don't cut straight into the cardboard, rather put your knife at an angle. Here is a photo to show what I mean:

nwlh5k.jpg
 
Vivi said:
Two things to keep in mind when cutting cardboard that will minimize dulling and the required force to cut the media...cut with the grain, and don't cut straight into the cardboard, rather put your knife at an angle. Here is a photo to show what I mean:

nwlh5k.jpg
Click to expand...

Why do you think cutting at an angle helps?
 
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