No matter what, there has to be some flexing of the blade going on...esp if the pressure actually is even. That flexing is what will cause the profile of the blade to change over time.
In addition to the blade flexing, Jon has taught me that sharpening happens where the pressure is placed. i.e. On a hamaguri edge, the two bevels are sharpened differently by changing where the pressure is more so than changing the angle at each bevel. Same principal here - with his sweeping motion and stationary hand position the pressure is different along different points on the blade and will cause uneven sharpening.
Shibui - simplicity devoid of unnecessary elements
That was very well, and diplomatically said.
I freely admit that even having seen Jon's videos (I'll be ordering Dave's soon as well), I tend to sharpen with a sweeping motion much like Mr. Kramer did in his video here.
That said...its something I've been consciously working on correcting.
The other thing to note is that this is clearly a video for beginners, to get people to who don't sharpen to actually sharpen their knives (or at least buy the sharpening kit). I find it is much easier to teach people to sharpen in sections. Kinda takes one element out of the equation. Very rarely if ever do I see people who are able to maintain angle, pressure, move their fingers along the blade and make an even sweeping motion from the get go. Much easier to start with sectional and get comfortable. He does touch on this, even if he prefers to sharpen in a sweeping motion, perhaps he should have spent more time showing beginners a good way to get started.
"God sends meat and the devil sends cooks." - Thomas Deloney
at the risk of sounding like a jerk, that was a little painful to watch.
the uneven pressure on the knife, there's just no way that tip got sharpened. and his stone holder kept jumping around on the counter and looks to me like a ridiculous contraption. and also, i could care less about a knife cutting paper. i used to shave my arm and cut paper and all that, but i think maintaining good knife geometry is seriously overlooked. keeping a knife nice and thin behind the edge will ensure that once it loses a little bit of its edge on that crappy poly board you have to use all day, it will still cut extremely well for the rest of the day or more.
Yeah the fingers / pressure not over the stone really bothered me. Aside from the reasons that others have already mentioned, it's also a much less safe way to sharpen especially when you start moving faster and / or as your fingers and the blade start to get wet and muddy. If your fingers slip off the blade when you've gotem centered on the stone, the worse cut that's likely to happen is a little skin off the finger tips. But if you slip with your fingers hanging off the edge of the stone like that, ESPECIALLY when using a sweeping stroke, the can get caught between the side of the stone and the edge and result in a really nasty injury.
"I gotta tell ya, this is pretty terrific. Ha hahaha, YEAH!" - Moe (w/ 2 knives). http://www.youtube.com/watch?v=YVt4U...layer_embedded
What I didn't like was that he wears gloves when using a bench grinder.