synthetic sapphire vs black arkansas?

[ballenagris]

I'm just getting started sharpening my benchmade folders, and I wanted to ask about using the sapphire vs the black arkansas in the lansky system. I'll mention that using the universal holder seems to do a much better job than holding it in my hand. Any and all comments are welcomed.

 

[Bill DeShivs]

I don't own a Lansky, but I do have a lot of whetstones. A hard Arkansas, used properly will give you a very sharp edge. Synthetic ruby stones can cut either coarse or fine, depending on how they are finished. Ruby will last a lot longer than the sintered diamond hones.
Bill

 

[QuietOned]

The sapphire stone in the Lansky is a bit different. I don't know exactly what it is but it has a ductile quality to it. Seems to alter under pressure, so it's best used with light pressure. The tension of higher pressure and the ductile quality seem to introduce weird strains in the stone, if you use it on too heavy a scratch pattern with a high pressure, the strain can cause the stone to "flex" and crack or chip out small pieces of the stone.

Light pressure and letting the stone do the work on reasonable (600 grit or smaller) scratch patterns I've not had a problem.

Using the universal holder does help in consistency, consitency does help in making better edges.

 

[EMcDannell]

I know this is an old thread but im trying to find out which of these stones will produce a finer edge aka which one is a finer grit and figured bump this rather than start a new thread

 

[Obsessed with Edges]

As for how grit compares, I can't say. But, the abrasive used for the synthetic sapphire will be much harder than the Arkansas stone. If you're trying to sharpen (polish) one of the more modern stainless steels, the sapphire is likely to be more effective. Especially, as has been pointed out, by using very light pressure. That, by itself, can make a big difference.

The hard Arkansas stone can polish carbon steel edges nicely, but won't be as effective on newer, harder and more abrasion resistant steels. I have a nice little black Arkansas pocket stone, but haven't used it much, because it's effect on modern stainless is almost negligible. It did do a decent job on a carbon-bladed Opinel I recently touched up.

 

[HeavyHanded]

The sapphire is aluminum oxide - about a 9 on the MOHs scale. The Arkansas silicates are about a 7. My own experience with the Arkansas stones is that the soft and hard are not aggressive enough to use on the tougher stainless steels. I have gotten good results from the translucent and surgical black when used as a finishing hone on these same steels. The density of the silicates is considerably higher on the finer stones and that must make a difference. I couldn't even clean up the factory bevel on a knife with 154cm using a soft Arkansas, the same knife sharpened with SiC sandpaper and finished with a surgical black worked very well. I produced similar results using a translucent Arkansas on a knife with Sandvic 13c26. Haven't tried on anything tougher.

That said I'd go with the sapphire.

HH

 

[flatface77]

I have a semi-related question & didn't want to start a new thread over it. I'm looking at the KME setup & really like diamond stones but their DMT selection only goes up to the 1200 grit. Would it be workable to go from that to the black or translucent Arkansas after the 1200? I don't know much about Arkansas stones or what grits they approximate in other types of stones.

 

[Obsessed with Edges]

Depending on the steel, the Arkansas stones may or may not work. Their biggest limitation is in sharpening the more modern, harder and wear-resistant steels. Arkansas stones aren't very hard by comparison to other abrasives (like ceramic, silicon carbide and diamond), and some knife steels might actually be harder and more wear-resistant than the stone itself. If you're looking to put a high polish on the edge, you might need to look for some other abrasive media (like ceramic/sapphire, very fine silicon carbide, 3M polishing tapes, etc.).

The 1200 grit DMT (9 micron) can put an excellent working edge on any blade. It won't be polished, but that doesn't mean it won't be wicked sharp (especially when used on a guided setup).

 

[flatface77]

Thanks. That's what I wanted to know. I have the DMT Aligner kit with all the available stones up to the 8000. I like the looks of the KME clamp but don't like having to stop at 1200 grit with the Dia-sharp stones. They do leave the 1200 screaming sharp but I get something extra moving on to the 8000 stone after quality time on the 1200.

I was hoping to be able to really go overboard on the 1200 like I do on my Aligner & get it as sharp as I can & then feather-touch it to a finish on the translucent Arkansas. I do use a lot of higher-end steels though, & they don't seem to have anything finer than the 1200 Dia-sharp other that Arkansas stones that fit their stone holder. I suppose I could use a stone as a blank & throw my Edge Pro polishing tape on it if all else fails. Maybe?

 

[Obsessed with Edges]

Thanks. That's what I wanted to know. I have the DMT Aligner kit with all the available stones up to the 8000. I like the looks of the KME clamp but don't like having to stop at 1200 grit with the Dia-sharp stones. They do leave the 1200 screaming sharp but I get something extra moving on to the 8000 stone after quality time on the 1200.

I was hoping to be able to really go overboard on the 1200 like I do on my Aligner & get it as sharp as I can & then feather-touch it to a finish on the translucent Arkansas. I do use a lot of higher-end steels though, & they don't seem to have anything finer than the 1200 Dia-sharp other that Arkansas stones that fit their stone holder. I suppose I could use a stone as a blank & throw my Edge Pro polishing tape on it if all else fails. Maybe?

I think that's a very good option, especially since you've already got the polishing tape. I've been using a DMT Magna-Guide a bit lately, with Dia-Folds up thru the EEF. As good as those edges are, straight off the DMT hones, I still find myself using wet/dry sandpaper at 1000 - 2000 grit, then stropping with Simichrome, to polish the edges after the DMTs. I've been impressed with the results, and I'm sure the polishing tapes could even take that further.

 

[flatface77]

I'm angle-challenged & manage to screw up stropping so I'm left finishing with feather-light fonishing strokes on whatever super fine media fits my rigs. The polishing tape seems a natural to slap on top of whatever I last used. I'll give that a shot this weekend on my TSEK sprint.

 

[David Martin]

EMcD, A good ceramic w/ sapphries in the bond will be much harder and cut better/quicker than a black Arkansas. Its not only this but their grain structures are different causing the black to cut and polish slower. They are used for two different purposes. HeavyHand is correct on their hardness, this being a clue toward use. I use both these when sharpening my razor, the ceramic first and Arkansas last to polish. The black while being some what softer can be used with good results up to steels like ATS-34. It being very forgiving is a strong suit as well and takes lots of stroking. DM