Knife feels duller with higher grits

Hi folks,
   A common issue some sharpeners have is that the knife seems to be not as sharp at 5,000 grit as it did at 1,000 grit.  The question is: Is the knife actually duller or does it just feel that way?


    It does happen and I am not absolutely sure why but I have some ideas and solutions if this is something you've experienced.  When I sharpen a knife, I always make sure that the knife is as sharp as I can possibly can on the first stone I use, all the stones of course but especially the coarse and medium grits, in other words, I don't rely on a finishing stone to get the knife sharp, it's already there by the time I get to that stage.

 

     I've had the opportunity to watch some people sharpen who have experienced this, i.e. knife is sharp until the individual moved up to 5k or 6k, it just seemed to get a little duller after that. In each and every case PRESSURE was the problem, too much of it. Once they backed off on the level of pressure things improved. I've been there and I've done the same thing.

     I'll go over the basics of what I think is proper pressure management, this is just the way that I sharpen, it works for me.

     Ive mentioned before that sharpening a knife is all about Burr Formation and Burr Removal and it starts of course with forming a burr. (After you've checked the knife anything that will hinder your sharpening, bent tip for example)

     The level of pressure that I begin sharpening with will be either heavy or moderate depending on the condition of the knife which will also determine what coarse stone I begin with, 120, 220, 320, 400, 500, 600 or 800 grit.  I need to use whatever pressure is necessary to form a burr. However, I always start with less pressure than I think I need, just to see how the burr forming process is coming along and in most cases it comes along just as I want it to.  LESS IS MORE - Remember that.

     Burr forming pressure only happens once on the one same knife. Once I have formed a burr consistent in size from heel to tip on both sides of the knife, everything I do next is about removing that burr, cleaning the edge. 

     Now that I have formed a burr using what I call P4 pressure I drop down significantly, a 50% drop in pressure as I don't want to form any more burrs and I have also moved to a medium grit stone at this stage, 1k or 1.5k (Shapton Pro 1.5k, I use it every day)

     Now comes the finishing stone and by this time I am using very light pressure and this may be the answer to the problem of the knife getting duller. If I used too much pressure at this stage, all that "cleaning" of the edge I just spent that last 10 minutes doing may be impacted if I use too much pressure and form a burr again. The burr may be extremely subtle, you may not be feel it and you certainly won't be expecting it. (Unless you are actually trying to form a burr which some people do, wrongly in my opinion but it's just my opinion).

     If your knife feels less sharp at 5k then it did at 1k go back to the 1k stone and use very light trailing strokes to remove any hint of a burr, to re-clean the edge and get it sharp again. NOW try the 5k stone, or whatever finishing stone you are using but really lighten up on the pressure. Use trailing strokes as if you are stropping on leather and see how it goes.

     The good news is that you can achieve startling edges with finishing stones, so the stones are not the problem, it's something else and in all likelihood it is a pressure problem.

5k, 6k, 8k, 9k and 10k
(I wonder why there are no 7k stones)

It takes time, patience and practice and more patience to nail down the pressure you use but again, LESS IS MORE, go easy, lighten up and concentrate on holding your angle, harder to do with added pressure. 

    Also remember that a good 1k edge can feel sharper as it has more teeth, more bite to it so if you think the knife is dull, test the edge, will it slice telephone book paper, arm hair?  (Ive done this myself,  it felt like the knife lost some of its edge but when I tested it on my arm it was very sharp)


Hope this helps
Peter