Sunday, 6 May 2018

Dull is on the prowl


     I get a lot of emails from folks learning to sharpen who complain about dullness setting in very quickly after they have sharpened the knife. Or the knife is sharp at 1,000 grit but seems to be dull after a 5,000 grit workout.

   I get so many of these questions that a pattern emerges and I think the answer is not to difficult to find and the solution is not hard to identify and put into action.

   Something I have seen first hand is improper use of a hone, (Steel) after sharpening.  The primary edge of a knife, when sharp, is a microscopically thin strip of steel that forms the Apex of knife and runs from heel to tip. If you pick up a Steel and slam it against the knife, the chances of you hitting the target area, which is the fatigued metal that has shifted out of place from the centre of the knife, the chances of moving that back into place with a steel is remote if not done with some attention to detail. I have seen cooks knock the edge off a a knife in 10 seconds with improper technique.

    Steeling, (honing) should be done carefully, and as in the top picture. So if steeling habits are poor, it is doom for the edge of a knife and a waste of time, especially when too much pressure is used.

Speaking of pressure:

Corey in Phoenix, amazing knife sharpener.

    A student told me that he was able to get the knife nice and sharp on the 1,000 grit stone but it seemed to get dull again after the 5,000 grit stone. I asked him to show me his routine and it rapidly became obvious that pressure was the culprit.

   Sharpening comes down to Burr Formation and Burr Removal. In order to form a burr a certain level of pressure is necessary of course, I call it P4 pressure, the heaviest pressure that I will use during the sharpening of one knife. Once I have formed the burr on both sides I reduce pressure by half and then again by half and then on the last level of pressure, P1 Pressure, it is merely a feather light stropping motion.

   By the time I get to a 5,000 grit stone, my pressure is light to begin with so in the case where the knife was getting dull again, the fella was just using too much pressure, forming burrs again and dulling the knife.  It takes practice to manipulate pressure but it is very important.

   Usually, a sharpening issue can be resolved by something very simple, it comes down to going back to the basics, the fundamentals.