Saturday, September 30, 2017

SHARPENING KNIVES BY HAND

SHARPENING KNIVES BY HAND

Photos by Craig Woods
Article by Heather and Kevin Harvey, Master Bladesmiths with the American Bladesmith Society and members of the Knifemakers’ Guild of Southern Africa
Hardworking hands in the photos – Kevin Harvey – fulltime bladesmith
As a child you may have watched your granddad restore the edge on a knife, seemingly by magic.  His old oil stone with its swayback from years of use, the smell of the oil and his leather strop are the props you remember from his magic performance.  Years later you dug out the props and tried his magic, but it didn’t work.  You had seen it being done, it wasn’t magic, but a lost art.

Anyone with the most basic tools can sharpen any edged item easily when shown how.  There are many good gadgets out there that you can buy to help “set up the correct angle” for sharpening, but you can just as easily learn to sharpen by hand.  Sharpening gadgets limit what you can sharpen, whereas sharpening by hand has no limitations.  You can sharpen an axe or a cut-throat razor using the same basic tools.

The equipment we use to sharpen by hand are Arkansas stones which you can buy in different “hardness’s”, soft, medium and hard.  “Soft” will remove a lot of material where as “hard” will be used to just touch up an edge.  Diamond hones are wonderful and also come in different “grits”, if you only buy one, buy a medium grit.  We like to use water on the diamond hones and olive oil on the stones for kitchen knives, otherwise light oil or paraffin.  Remember to wash the stones/hones  after use with a little bit of dishwashing liquid and water to remove the steel grit that is left after sharpening.  A leather strop is important as the last step in sharpening is to remove the burr that you create during sharpening.  A makeshift strop can be an item as simple as a piece of firewood, your leather belt or the rubber sole of your boot, after all only you only need to flex the burr backwards and forwards, until it breaks off.

Other useful sharpening tools are tapered diamond rods for sharpening serrated edges and fold-up portable small diamond hones that you can carry with you on camping/hunting trips. 

Useful hints are to use a damp dishcloth to secure your stone to your kitchen table and protect the counter surface.  Carry a portable sharpener on your excursions and don’t be afraid to sharpen by hand.  Practise on a few of your cheaper kitchen knives until you master the skill, then you won’t be nervous about sharpening your custom made hunting knife.

People are obsessed with “keeping the correct angle” when sharpening, but it is not critical, so long as you are consistant with the angle you have chosen.  Sharpening angles differ depending on the type of knife and the work it is expected to do.  You should not put a razor edge on an axe, just as you wouldn’t put a chisel edge on a filleting knife.  You want your edge to match the purpose of the knife. 

Lubricate the stone/hone with water or olive oil (tastes nicer than paraffin!) and cut into the stone as if trying to shave off a slice of the stone.  Keep your angle constant and sharpen all areas of the cutting edge, from where it starts near the handle all the way to the point.  Repeat on the other side of the cutting edge.  Keep sharpening until you can see a “burr” (bright shiny ribbon of steel) on the entire cutting edge.  It is now time to strop off the burr on the back of a leather belt.  Your knife is only truly sharp once the burr has been removed otherwise the burr just folds over your sharpened cutting edge, making the knife feel blunt.  Stropping is done by dragging the cutting edge over the strop, (opposite to cutting into the stone) swapping sides, at a slightly steeper angle than you sharpened at.  You will only need to strop a couple of times before you see the burr break off. 

To test for sharpness, see if the edge will bite into your nail when gently pushed onto it at an angle.  Test the entire cutting edge and if any part of it “slides” off the nail and does not “bite”, you will need to re-sharpen that area of the blade.

CAPTIONS TO THE PHOTOS

Variety

Shows various different sharpening stones and diamond hones.

Showing the angle

This would be a good angle (15˚ to 20˚ ) to use for a general purpose knife.

Pushing into the stone

Sharpen by pushing into the stone as if trying to lift a postage stamp off the stone.  A diamond hone is used in this photo with water as lubrication.

Arkansas stone

A natural sharpening stone (not carborundum) is used with olive oil as lubrication.

Serrations

Serrations can easily be sharpened with a tapered diamond rod, one tooth at a time.

Portable diamond hones

Very handy to carry with you while camping or hunting to touch up knives.  Keep your angles the same as you would on the sharpening stone.  With these small sharpeners, the sharpener is moved over the cutting edge, as opposed to the edge moved over the stone as with the larger sharpeners.

The burr

After sharpening you will see the raised burr which needs to be removed by stropping to achieve a sharp edge.

Stropping

The most important part of achieving a sharp knife is the stropping after sharpening to remove the burr that you have created.

Testing sharpness


Carefully and gently push the entire blade, section by section, into your thumb nail at an angle.  Where it “bites” it is sharp, where it “slides” it needs to be re-sharpened.