Sharpening a knife may come across as an overly simplified process involving a few swipes across a stone. Let me assure you though that there’s quite a bit more to it than meets the eye. Although we wouldn’t say that it requires a neurosurgeon’s dexterity but the knife sharpening process indeed has its nuances that we must acknowledge to get the most out of it. Applying the correct sharpening pressure is one of them.
Within this post, we will discuss the specifics of what the correct sharpening pressure is, its importance and what pressure to apply on whetstones with different grits.
What Is A Burr
Before we get into sharpening pressures, it is important to first understand what a “burr” is. A burr is essentially raised metal over the knife’s edge. When metal is being removed during the sharpening process, a super thin raised metal layer is formed on either side of the edge.
A raised burr is a sign that the knife is being sharpened correctly. The absence of burr indicates that you have been sharpening the sides of the blade rather than its edge.
What Pressure To Apply
There are essentially three main sharpening pressure variations; the burr formation pressure, burr removal, pressure and refinishing.
Burr Formation Pressure
Burr forming pressure is essentially the heaviest pressure you could use on a knife. Be careful though as this heavy a pressure is only warranted for knives that are quite dull. Even then the pressure would depend on the degree of dullness.
The best way to determine this is by first checking the sharpness by cutting a paper. If it doesn’t cut at all then use a heavy pressure. If it cuts but is somewhat resistant then reduce the pressure accordingly.
Also, it’s better that you start off with a moderate pressure and continue for a couple of minutes. If the burr isn’t formed then increase the pressure a bit. For burr formation usually, a coarser 400 grit whetstone is recommended.
Burr formation can take up to 7 minutes depending on the dullness of blade, coarseness of the whetstone and how comfortable you are sharpening. Also, remember that the burr has to be formed on both sides of the blade and you have to frequently monitor that an even burr is being formed from tip to base.
Burr Removal Pressure
This is where an edge is formed by the removal of metal remains. For burr removal reduce the pressure by 50% as compared to burr formation. This is also done on a coarse stone.
To ensure that the burr is indeed being removed, you must check the edge frequently. Just hold the edge up in bright light and look for any reflections on the blade. If you don’t spot any reflections that means the burr has been removed properly.
This is when the edge is polished on a fine 5000-8000 grit whetstone with very light pressure.
So there you have it; another nugget that’ll keep your knife razor sharp for years to come!