What materials are really hard on a knife's edge?

S

Swedge

Joined
Dec 23, 2008
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There was just a thread on cardboard, and there were a number of posts on cardboard being hard on a knife's edge.

What other materials are hard on a knife's edge?

I'm not talking about trying to cut through cinder blocks or car doors.

I am asking about materials that most people would cut with a knife: food (some types of food harder on an edge than others?), branches or finished woods, wallboard, carpet, tar paper, tape, insulated wire, deer hide (when skinning), etc.
 
Cardboard - dulls edge fast. Beef or pork bones - can roll or even nick blade. Any kind of wire. I find cutting zip ties also hard on the edge, not so much the actual cutting of the zipties, rather that so much force is required in the cut that the blade tends to contact other things after slicing through the cord.
 
Fiberglass insulation will eat an edge up almost instantly.

Sheetrock isn't all that bad, but the fire-retardant fiber board ceiling tiles are for sure.

Old carpet. Not so much the carpet itself, but the dirt imbedded in the fibers is very abrasive. Animal fur/hide is much the same.

Old mastic adhesive is another edge killer.
 
Plastic strapping and strapping tape.
 
I use a utility knife for any construction duties. My pocket knife is used when the correct tool isn't available. I've noticed dry wall to be rough on an edge. I also avoid cardboard and just slice the packing tape to open boxes.
 
To me the plastic clamshell packs seem to dull the edge of my knives a bit.
 
Cardboard is not as bad as people say. I cut cardboard all day with my S30V knives and have no trouble with edge retention. A few swipes on my Sharpmaker every night after work keeps a flawless working edge. People that say cardboard is harsh are either using inferior steel, or working with an edge angle that is too thin. Knifeknuts seem to be obsessed with having the sharpest, thinnest edge possible. That is nice and all, but a utility knife really benefits from a thicker, more robust edge. Factory edges are usually pretty well thought out.
 
Leather is pretty hard on an edge. Hide and hair can be too.
 
J85909266 said:
Cardboard is not as bad as people say. I cut cardboard all day with my S30V knives and have no trouble with edge retention. A few swipes on my Sharpmaker every night after work keeps a flawless working edge. People that say cardboard is harsh are either using inferior steel, or working with an edge angle that is too thin. Knifeknuts seem to be obsessed with having the sharpest, thinnest edge possible. That is nice and all, but a utility knife really benefits from a thicker, more robust edge. Factory edges are usually pretty well thought out.
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Depends on the clay content of the cardboard IIRC.
 
I think the worst thing for an edge I've cut is skateboard grip tape. I've had two knives in sandvick stainless at low angles take some bends, rolls and chips, and other "economical" stainless steels like AUS8 and 8Cr13MoV get completely dulled cutting the griptape needed for a single board. I used AUS8 Boker Trance at about 5 degrees per side last time and surprisingly only got some micro chipping that could be taken care of in a single sharpening. I could use a box cutter, but it's fun seeing what this very abrasive material does to different steels and geometries.

J85909266 said:
...or working with an edge angle that is too thin. Knifeknuts seem to be obsessed with having the sharpest, thinnest edge possible. That is nice and all, but a utility knife really benefits from a thicker, more robust edge. Factory edges are usually pretty well thought out.
Click to expand...

What knives have you had decrease in edge retention on cardboard with a thinner edge? Have you ever had the edge on a box cutter (Thin) fail when cutting a box?

I've had very good results using thin edges on cardboard myself. Makes the job a lot easier if anything.

http://tinypic.com/player.php?v=uc9ll&s=5

My box cutter is a ZDP189 Caly Jr. taken down to one of the thinnest geometries I've ever put on a knife. :D
 
Sandpaper. I only use cheapo ultility-blades on it.

Rocks. I'm serious about this one. Most of my edge damage comes from accidental rock contact. This happens a lot to me when cutting old slings from rock-climbing anchors. I also destroyed a saw blade when I was sawing a root-burl and hit an included rock.
 
J85909266 said:
Cardboard is not as bad as people say. I cut cardboard all day with my S30V knives and have no trouble with edge retention. A few swipes on my Sharpmaker every night after work keeps a flawless working edge. People that say cardboard is harsh are either using inferior steel, or working with an edge angle that is too thin. Knifeknuts seem to be obsessed with having the sharpest, thinnest edge possible. That is nice and all, but a utility knife really benefits from a thicker, more robust edge. Factory edges are usually pretty well thought out.
Click to expand...

When you have to touch up your S30V blade nightly to keep it at a good sharp edge, you are cutting material that is tough on the blade. Even if it's just a few swipes it still means that you are having to do upkeep to keep that blade sharp. Cardboard is definitely tough on the blade plain and simple. I've gone weeks without having to sharpen or even touch up an S30V blade, but that's without cutting cardboard at all.
 
That nasty polypropylene rope. It's the cheap stuff that the use on water ski's and such when people are too cheap to get nylon. That stuff it terrible to cut.
 
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