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Complete Guide: How To Sharpen A Knife With A Rock

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Knife sharpening can be challenging enough with commercially produced or cut stones and other sharpening devices. But, you may find yourself in a situation where you don’t have these modern options available to you.

In this case, you can revert to humanity’s roots and try your hand at sharpening your knife with a rock. So what is the best rock to use to sharpen a knife, and what are the steps to get it done?

To sharpen a knife with a rock, choose a smooth rock with a fine grain. Wet the rock with water or spit and use the rock as you would use a whetstone. If the rock is small, you can move the stone over the blade rather than moving the blade over the stone. Make sure you keep your angles consistent.

Sharpening a knife with a rock is the classical way that you see movie characters sharpening their knives and swords, and it is true that this method of sharpening a knife works.

There are, however, some things to look out for when trying this method to make sure you have success and end up with a sharp knife rather than a ruined blade!

If you are interested in checking out the best whetstones for your knives we recommend and use you can find them by clicking here (Amazon link).

Why Sharpen Your Knife With A Rock

How To Sharpen A Knife With A Rock
How To Sharpen A Knife With A Rock

Sharpening your knife with a rock needs to be approached with some caution, and it is not a method that is recommended if you have modern sharpening methods at your disposal.

There are some instances where you may need to employ this method over a more modern method, but it should generally be a last resort option.

You may find yourself out in the field, and you need to use your knife to perform a task, and you take it out only to discover that your blade is not as sharp as you thought it was and you don’t have a sharpener with you.

A survival-type situation would be another scenario where you may not have access to a commercial sharpener and need to recondition the edge of your knife because of the rough use of the blade.

You could also have gone camping and forgotten to bring a knife sharpener along, and your only other option to using a rock to sharpen the knife would be to make do with a dull knife.

If you are contemplating using a rock to sharpen your knife, then it would be prudent to know what the best way to do this would be and if there are some nuances to this method that you should be aware of.

How To Sharpen A Knife With A Rock

Sharpening a knife with a rock is not as simple as grabbing the first stone that you see and start rubbing it on the edge of your knife.

There are some techniques to the task and also some correct choices that need to be made if you are to have success using this method to restore the edge on the knife.

What Type Of Rock To Use To Sharpen A Knife

Sharpening a knife with a rock or a stone is nothing new, and the modern whetstone is the evolution of this technique from the ancient beginnings of this practice.

While some modern whetstones are commercially manufactured abrasives, the Japanese Waterstones are natural rock that is quarried directly from the ground and cut into the traditional square shape that we purchase.

So what is the right type of rock to use to sharpen your knife? Most stones are not made from one kind of material, which means they are not uniform in abrasive qualities or hardness.

Thus, using any rock could damage the blade further and make the sharp edge of the knife jagged, which is of no use to you.

The best rocks to select as a potential sharpening stone would include the following.

  • A smooth river stone. A stone that has been in the river would have been eroded to become smooth, so the softer material would have been removed from the stone, and it will be of even hardness. The grain on these stones is also usually fairly fine, which is good for sharpening the knife.
  • Sandstone. Sandstone is made of fine sand particles that have the same abrasive qualities as sandpaper. The finer the grain of the sandstone that you can find, the better it will be as a sharpening stone.

Whichever stone type you choose, you need to make sure that the grain structure of the rock is as fine as possible; the surface should feel like fine-grit sandpaper to the touch. The shape of the stone that you choose should also be as flat as possible.

TIP: No matter what you use to sharpen your knives it often happens that it loses its sharpness relatively quickly. Do you know why this is happening? Find out the main reasons in the article below:

Why Do Knives Lose Sharpness (So Fast)? 5 Common Reasons

Method For Sharpening a Knife With A Rock

Now that you have the rock that you are going to use to sharpen the knife, it is time to get down to the actual method that you will use to put the edge back on the knife.

There are a few techniques that you can use to sharpen the knife with a rock.

  • Rub the rock on the blade.

If the rock is small, about the size of the palm of your hand, place your knife flat on its side and, with slow even strokes, rub the stone along the length of the sharp edge, making sure to maintain the same angle throughout each stroke.

Keep the stone wet with water to make the sharpening more efficient. The stroke should be from the spine towards the edge and never the other way around, as this can dull the edge or result in you getting cut.

  • Rub the blade on the rock.

Lay the stone flat on another rock, or the ground, or your leg. Wet the stone and move the blade across the length of the stone, across the full surface of the sharp edge, making sure that you maintain the same angle the whole time.

This method is the same way that you would use a normal commercial whetstone.

  • Create a V-shape with two stones.

If you can find two stones that are the same coarseness, you can position them so that they create a v-shape angle and pull the blade smoothly through the v-shape to sharpen the edge.

You will need to match the angle of the v-shape to the secondary bevel of the knife to keep the angle consistent on the blade. Keep the stones wet as you do this to increase the efficiency of stones. This method mimics sharpening the knife on a v-shaped carbide pull-through knife sharpener.

It is important to keep the stones wet as you pass the knife across the surface. This helps to form a slurry, which will help to carry the swarf away from the edge of the knife and also make the stone a more efficient sharpening tool.

If you don’t have an abundance of water, you can spit on the stone to offer a liquid lubricant to the sharpening operation.

If you have some leather available, such as in the form of a shoe or a belt, it would be worthwhile passing the blade over the leather and using it as a strop to do the final honing or polishing of the edge.

What Else Can You Use To Sharpen A Knife?

A rock is not the only alternative means that you can use to sharpen a knife in a pinch. Some of these options may even offer better alternatives to using a rock because they would be of a consistent hardness and same grain structure.

  • Glass.

Glass, specially hardened glass, makes a very good knife sharpening alternative since it has a very even and consistent service. 

  • Ceramics.

An unglazed piece of ceramic can be used to put a serviceable edge on a knife in a pinch. It is not the best way to sharpen a knife, but in an emergency situation, it can work. You can use the bottom of a coffee cup, which usually has an unglazed edge around the bottom.

  • Leather.

If you have a piece of leather available to you, either a belt or leather shoes, try to strop the knife on the leather to hone the edge before using more drastic measures to sharpen the knife.

TIP: One of the best knives you can own is Japanese knives. The best tool for sharpening Japanese knives is the whetstone. But can you also sharpen Japanese knives with steel? Find out more in the article below:

Can You Sharpen A Japanese Knife With Steel?

Conclusion

While sharpening a knife on a rock may not be the most ideal method of putting the edge back on your blade, it does work. It can do a serviceable job if you are in a pinch and need to fix the edge on your knife.

With a bit of care in the selection of the stone, some patience, and paying close attention to the angles that you are using to sharpen the blade, you can achieve a very useable edge on the knife that will be suitable for most bushcraft style tasks.

TIP: Are you looking to buy a new whetstone? Check out our recommendations (we personally use the first three ones):

Our PRO choice whetstones combo (Amazon links):

Our budget choice (Amazon link): Sharp Pebble Extra Large Sharpening Stone Set

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Sharpy_-_Stainless_knives