Question on Switching Stones

[GB]

I am using an Edge Pro Apex system. I have a couple of questions on switching stones.

1. I am assuming that the finer grit the stone then sharper the edge can be. Is this correct or is sharpness not a function of the grit size?

2. What is the process for going from one stone to the next. For instance, if I were starting with a medium and then going to a fine would I raise the burr with the med first then remove the burr then start over with the fine and do the same thing?

 

[Rob Babcock]

In a sense the finer stone doesn't really get the knife sharper, it makes the edge smoother. Sharpness is defines by the angle- if you do a poor job with the coarse then no amount of work with the finer ones will help. Now, it will definately cut many things better once you've worked thru all the stones and will be "sharper" in the way most people use the term. But the heavy lifting is done with the coarser stones.

That said, the ultimate in polished edges comes from using the finer stones, then the PSA tapes/post-it notes with compound.

 

[Dr.Awkward]

Yes, ideally you'll want to remove the burr before moving up the stones. If you don't, you can sometimes get an okay edge anyway, but what you're really doing is pushing the burr from side to side and making it smaller and smaller. You might use a wine cork to remove the burr (just gently cut it).

Your edge will be as "sharp" with all the stones; in other words, the angle will be the same (discounting the concept of microbevels for the purpose of this post!) But the edge will get finer and more highly polished as you move to higher grit stones.

Imagine you were using sandpaper on a piece of wood: coarse sandpaper helps you rough out the shape, while finer grits help you remove the scratch marks that were left by the coarser paper. When you finish up with a very fine grade, the surface of your wood will be very smooth. Ideally (yeah, right!) there would be no evidence of sandpaper used at all.

In the same way, "ideally" your knife edge will be a perfect angle, the perfectly smooth bevel edges tapering down to meet at the width of a single molecule. (Well, to a single carbide, anyway. But I digress...) This is where stuff like CrO2 polish and leather strops come in, as they polish the edge much finer than most stones do. I'll let someone more knowledgeable than myself take it from there, as I'd like to learn more about honing myself!

Compare -say- the factory edge of a Chicago Cutlery knife, which is quite toothy (at least mine were) with a razor blade, which is quite smooth. A toothy blade is often good for utility work, like cutting rope and such. It can also work very well for cutting stuff with skins like tomatoes or grapes. I've experimented with toothy edges on my own pocket knives/utility knives, etc. but lately I've been leaning toward the "finer is better" school of thought.

Try slicing a tomato after removing the burr at each step up the stones. See how much you have to move the knife versus letting the knife fall through under its own weight. When you're done, you should be able to hold the knife blade-up and drop a ripe tomato onto it from less than a foot away, and the 'mater should just fall in halves to either side. It's always easier to understand when you can feel the difference!

-Dawk

 

[GB]

Thanks guys. That is helpful info.

So if I am understanding correctly, using a finer stone will not necessarily get me a lot, although it sounds like even that is up for debate. Maybe a better way to say it is that some people would say it is just for aesthetics while others would say there actually is some benefit. Does that sound accurate?

 

[SShepherd]

I'd have to say no, a polished edge it important for delicate cuts or for knives with a high hardness

 

[Dr.Awkward]

Chiffonade some basil with an "okay" edge and with a good, highly-polished edge, and see how long it takes the herb to turn dark. A good edge makes a difference!

 

[GB]

So an edge is only good if it is polished?

 

[Dr.Awkward]

So an edge is only good if it is polished?

Er, by that I meant "highly-refined" or, in other words, using your finest stone. Sorry for the confusion!

I guess the highest stage of sharpening could be referred to as "polishing", as the scratches become too small for the human eye to see.

 

[SShepherd]

So an edge is only good if it is polished?

it's a bit more like"the right tool for the right job"

after that its personal preference, although I have to say, I prefer a polished edge on all my knives

 

[Rob Babcock]

It's difficult to explain properly, but yes, progressing upwards thru the finer stones will make your knife cut better. It's just that the primary sharpening has to happen with the coarser stones in order to get the benefits. The first stones will cut the primary bevel- if you choose to microbevel you can do so but even that can be done with a 1000 grit or so. Finer stones will refine the edge to a great deal, but only if the edge is there to begin with.

So yes, in practical terms you do use finer stones to get your knife "sharper" in a sense, but I still don't really like to say it that way. A polished edge will definitely do things you can't do as well with a "rougher" edge, like push cutting and slicing tissue. As already stated, you can easily see that you're doing less damage to the food by finely julienning basil or slicing tomatoes very thin. The polished edge glides thru food with very little effort or pressure vs a less polished edge. Still, many feel that a "toothier" edge is better for stuff like cutting cardboard and leather.

 

[SShepherd]

It's difficult to explain properly, but yes, progressing upwards thru the finer stones will make your knife cut better. It's just that the primary sharpening has to happen with the coarser stones in order to get the benefits. The first stones will cut the primary bevel- if you choose to microbevel you can do so but even that can be done with a 1000 grit or so. Finer stones will refine the edge to a great deal, but only if the edge is there to begin with.

So yes, in practical terms you do use finer stones to get your knife "sharper" in a sense, but I still don't really like to say it that way. A polished edge will definitely do things you can't do as well with a "rougher" edge, like push cutting and slicing tissue. As already stated, you can easily see that you're doing less damage to the food by finely julienning basil or slicing tomatoes very thin. The polished edge glides thru food with very little effort or pressure vs a less polished edge. Still, many feel that a "toothier" edge is better for stuff like cutting cardboard and leather.

please tell me where those places are, so I can make sure not to eat there

 

[GB]

Thanks Rob. That helps me a lot!

 

[Rob Babcock]

please tell me where those places are, so I can make sure not to eat there

Not to worry, unless your diet includes cardboard and leather (perhaps McDonalds?).