Advantages of high and deep hollow grinds on pocket folding knives...

[FortyTwoBlades]

Here's a cheap $4 Italian slip joint that was originally a pretty thick FFG fully serrated recurve shape that I reground to a FHG.

 

[REK Knives]

Another advantage is that the tip will actually covert to a flat grind and be thicker /more robust depending on how you do the hollow (if you don't rotate the handle while grinding but only go straight across)

 

[Wowbagger]

Chris Reeve, Buck, Loveless ... can not be wrong.

You forgot to include Bowing in that list.
I'm just saying.
As far as slicing food, or other things (I cut soft largish diameter rubber tubular objects at work) . . . to a fairly decent effect the transition at the top is going to kick the knife to the slice side as it rides on the main body being cut thous undercutting at the bottom and probably thickening the slice near the bottom. A flat ground knife will do this to a lesser extent; of course the right knife for the job is ground with a single bevel to the side that is the dominant hand of the user.

I hear you as far as longevity for long term sharpening. Personally for the stuff I cut I find once I get a knife reprofiled to the geometry for the job the amount of material I have to remove to get it silly sharp again is miniscule. Another reason to use a Sharpening Jig; the highest percentage of passes are actually right on the edge and not higher up the bevel or taking the occasional too steep stroke which sets the process back rather than getting to the goal with as few passes and thus with the least material removed.

Hollow to the spine sounds intriguing; I need to learn more.
On first blush a very high convex all the way to the spine sounds better to me from an engineering stand point. Sure grind the area behind the edge very thin first but make the spine thinner than the area more in the middle of the blade. Why ? That is a very good question; one could just use a fillet knife and be done with it. I've been tempted to EDC one. Seriously though the steel above the middle of the knife toward the spine is still acting to strengthen the knife against breakage as well as make a thin knife less whippy / remove any significant whippyness.
Apparently that's not a word . . . at least not in reputable circles.

 

[Wowbagger]

the classic Douk-Douk is a perfect example of a factory hollow grind done right in my opinion.

OHHHhhhhhh . . . I didn't realize that's how they are ground. Cool stuff.

 

[Wowbagger]

Here's a cheap $4 Italian slip joint that was originally a pretty thick FFG fully serrated recurve shape that I reground to a FHG.

Oh yeah baby ! ! !
You need to post more of your personal knives please.
That's some serious mod there. The handle is reminiscent of the Buck 110; one of the best knife handle shapes out there in my view. Haha I have been tempted to do the same thing to one of my 110s . . . someday . . . someday.

 

[Mr.Wizard]

Is there a benefit, other than looks perhaps, to the rounded plunge area seen on this knife? It results in a section that has no edge. I would rather have a sharp transition from the hollow to the flat shoulder of the ricasso, rather like the nail nick on this knife.

 

[Obsessed with Edges]

Is there a benefit, other than looks perhaps, to the rounded plunge area seen on this knife? It results in a section that has no edge. I would rather have a sharp transition from the hollow to the flat shoulder of the ricasso, rather like the nail nick on this knife.

That's the downside of such an extreme hollow on a thick-spined blade. Not just on hollow grinds, but it happens with most any relatively thick blade ground to a thin edge; the transition from the cutting edge to the ricasso will have to be very extreme. Some will have a choil or 'sharpening notch' between the ricasso and the cutting edge, so it can be be sharpened fully. I'd considered doing so with this one, grinding a sharpening notch, but I tend not to like them for their tendency to grab or snag materials being cut. I can live with the little bit of unsharpened edge there, as it at least won't get hung up on things.

 

[David Martin]

I don't care for a sharpening notch for that reason^. DM

 

[Mr.Wizard]

Yes, I prefer a sharp transition e.g. on the Spyderco Gayle Bradley.

 

[Wowbagger]

OK, here you go
I happened to run across this photo while looking for another thread.
See the pronounced curve in the apple from a hollow ground knife and a thin blade with a high hollow grind no less. Case Trapper. I love the knife; slices apples goofy though.
Go here LINK > > > second photo.

 

[Obsessed with Edges]

Apples are odd in how they cut with a given knife. I've noticed my Opinels (shallow convex) don't handle them well, because the apple tends to pinch the blade hard, almost vise-like, wedging it in and making it difficult to push through. I used to notice also, watching my Dad cut an apple with a Chicago Cutlery paring knife (hollow/sabre-grind), it had the same effect on that knife. My Dad would put the apple on the countertop and push the blade through it; the end result was the edge of the blade smacking the countertop hard.

The one thing making the difference for me, in slicing a whole apple, is using a tall blade, like a chef's/cook's knife or a santoku. The height of the blade makes a difference in preventing the apple from closing or pinching on the spine of the blade, as will happen with a narrow-bladed knife like a parer or a pocketknife. With such a narrow blade in the relatively rigid interior of the apple, I also believe any asymmetry in the blade's grind, side-to-side, will tend to 'steer' the cut one way or the other. I think that's more likely the culprit in quirky, curved cuts like the apple pictured previously, cut with the trapper blade, rather than with the hollow grind profile itself.

My favorite tomato slicer is a hollow grind. I like using a Case Sod Buster Jr. for smaller tomatoes, like Romas for example. It has a full-height hollow grind like the previously mentioned trapper blade and I've also put an acute, polished convex at the edge of it. I've never had any issues with other than straight cuts through those, using that hollow-ground blade.