Sharpening with Sandstone

Father & Son Traditional Sharpening

Father & Son Traditional Sharpening

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Jun 11, 2012
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Has anybody ever used sandstone to sharpen their Busse? Sandstone has apparently been used for quite some time sharpening knives, before the common use of synthetic stones. It is a sedimentary rock composed of mostly microscopic sand particles of varying types.

I collected two blocks of sandstone in the desert recently for experimentation with sharpening/regrinding my Scrap Yard 511. One was similar in size to a bench stone, the other smaller so it can be used in hand as a file. In order to achieve a perfectly flat grinding surface, I used the flattest surface of each rock to grind against one another with a small amount of water added as a cutting fluid.

I used the smaller piece in hand as a file after soaking with water to regrind the primary bevel my SYKCO 511. The larger piece worked well as a bench stone in the traditional way you would use a waterstone, working the secondary bevel in a back and forth motion until the apex had been cleanly formed, then stropped backwards to eliminate any burrs that may have formed.

The finish that is left when keeping the scratches in a uniform straight line from edge to spine has a subtle dull satin appearance. It actually cuts quite fast with SR-101 at 58-60 RC when the surface is kept wet to moist in order to create a thick mud on the surface that flows well when kept sufficiently saturated with water.

Pics added below..... :)
 
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Not a "knife" but I have seen all manner of other blunt objects sharpened on sandstone. Expedient method and all that ... ;)
 
I've used the top of a concrete wall before, also using water as a lubricant. I would think the a brick would work as well.
 
Yes and it works, but you wear the sand stones out faster than typical sharpening stones. As for grit, I can say for sure but the grit feels like about 100-300 ish and it really works well. You put more pressure for stock removal and less pressure for honing to a finer edge. You can do this on clay brick as well.
 
Regarding the grit, I would be pretty confident in saying that it would be a large range of grit sizes below the size of what is considered small enough to be a grain of sand. I hypothesize that the variation in size, combined with the constant shedding of fractured abrasives and surfacing of fresh abrasive allow for relatively fast grinding by hand. I also believe that as you grind, the grit is reduced in size due to fracturing so who knows. I do know that I am satisfied with this level of finish, though using a higher grit stone after could boost performance in some ways.
 
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Here's what it looked like while I was regrinding the primary bevel, lots of thick mud ..... :thumbup:

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Here's the result as of right now.....

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As you can see, the primary grind has been blended into the secondary (edge) and convexed into a single blended bevel. This convex shape is due in part to changing grinding angle during the process, also the stone I was grinding became concave as it wore down and dished. I used pretty firm pressure with stone in hand for this, you could really hear how aggressively the sand was cutting.

I started regrinding this knife with an extra coarse DMT diamond stone, which was much slower grinding in my opinion than this method using sandstone and firm pressure. I do believe the 511 came factoy with a very slightly convex primary saber grind also (1 degree off flat) so it wasn't perfectly flat to begin with. I will likely continue regrinding to blend the primary up to the spine to make it full convex.
 
Going to try this soon! I'm surrounded by Limestone and Sandstone around here! I wonder how limestone would work being a little finer in overall grit? Might visit a stone cutter for some flat pieces as well, those fellas are everywhere with the popularity of limestone as a building material these days.
 
Not too sure about how well limestone would work. I believe most rocks would work to some degree, but I have read that shale and sandstone are preferable. I am also surrounded by an abundance of sandstone here, probably shale too for that matter I just don't know what it looks like.

I have found that different pieces of sandstone can behave quite differently. The first piece I was using in the pictures created tons of mud with use and dished very quickly. It quickly wore down to the point it was not useable anymore. The second piece I tried created very little and wore slowly, I also got the impression it cut less aggressively and left a finer finish.
 
bear with me here as I am trying to unearth (heh pun) terminology from college way back in the early 90's

Sandstone is the roughest form of the sedimentary rock in question, there are a few larger with different terms. Sandstone is as the name implies, of sand like consistency. Often its concreted with very fine clay's

Limestone is a finer sedimentary rock, often found with sandstone in a layered deposit. Limestone is very fine in texture but also like sandstone is not very strong. It breaks up fairly easily.

Shale is a very fine sedimentary rock, often found in fine layers as well. It produces very nice fossil records because of its fine texture. Shale is also very nice as its easy to strike off very flat plates. Not so easy with Limestone or Sandstone.

Might have my stuff a little jumbled, I've slept since then, and a few incidents have erased a little as well. But will always love my time in Geology and Archaeology in college.
 
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