Dull edge after cutting sandbags?

J

JoshBarrow

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Apr 2, 2020
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After a long time of carrying around sandbags in the back of my truck, I decided it was time to ditch them for the summer. I just bought a brand new bark river bravo 1.25 LT in CPM 3V steel which I used to slice open my six sacks of sand I had sitting in the back of my truck. It had a razor edge on it, and it was the first time using it other than a few peices of paper when I first unboxed it. After disposing of the sand I went home and I sharpened my spyderco, and once I put a good edge on it, I wanted to compare it to my new bravo. But when I tested out my bravo, it could hardly even cut paper. I was kind of shocked. Isn't 3v steel supposed to be good? How can just a couple of swips into bags of sand dull 3v that quickly? Is it a heat treat issue? I'm fairly new to knives, and am nowhere near as knowledgeable as a lot of guys here on these forums. I get that sand is the original form of glass, which is horrible for thin steel edges, but I didn't think it was capable of dulling a so called "super steel" in 6-7 swipes. What do you guys think? Bad heat treat? Or is sand and sackcloth that hard on edges?
 
JoshBarrow said:
After a long time of carrying around sandbags in the back of my truck, I decided it was time to ditch them for the summer. I just bought a brand new bark river bravo 1.25 LT in CPM 3V steel which I used to slice open my six sacks of sand I had sitting in the back of my truck. It had a razor edge on it, and it was the first time using it other than a few peices of paper when I first unboxed it. After disposing of the sand I went home and I sharpened my spyderco, and once I put a good edge on it, I wanted to compare it to my new bravo. But when I tested out my bravo, it could hardly even cut paper. I was kind of shocked. Isn't 3v steel supposed to be good? How can just a couple of swips into bags of sand dull 3v that quickly? Is it a heat treat issue? I'm fairly new to knives, and am nowhere near as knowledgeable as a lot of guys here on these forums. I get that sand is the original form of glass, which is horrible for thin steel edges, but I didn't think it was capable of dulling a so called "super steel" in 6-7 swipes. What do you guys think? Bad heat treat? Or is sand and sackcloth that hard on edges?
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I think there are a lot of things that could affect how well the edge could hold. 3V is a great steel for outdoor use--I think it is a good balance between toughness and edge retention (also dependent on geometry, heat treat and use), but it surely is not that kind of steel solely known for edge retention.
 
Cut into the dirt around some weeds with a very sharp Spyderco K390 blade and it did not stay sharp for long. Took me forever to resharpen and will not do that again. I was going to say something silly like making sure to cut through the bags with a consistent angle but decided not to.
 
This requires more research - get more sandbags and test all your knives on them! That would provide some interesting comparisons. They will all get dull, but how dull?
 
Sand is essentially rocks broken down to a wee bit before microscopic!!! So you were cutting rocks! Six swipes on a rock will give you a nice butter knife!!
 
Cutting things on a ceramic plate will also dull your edge. We use ceramics to sharpen knives too. Same deal with sand. If all you have is your knife to cut open sandbags, by all means use it. Better to use a razor knife though, since razor blades are cheap and disposable (although I do sharpen them sometimes).
 
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