Thread: Ceramic hones ok?

Something tells me this debate's never going to end or be completely resolved!

I just got an Ultra Fine for Christmas . Flattened one side just a little, all it needed. Took my new Red Imp That I had just honed on my Coti & did 20 rounds on my Ultra fine, stropped it on my Koken Cordavan Shell strop I haven't ever had a nicer edge on a razor. Shaved like butter. It kept the smooth edge of the Coti but just sharpened it a couple of notches!

Dave "Slawman" Huffman

If you are talking about a Spyderco UF, then you just trashed that side of the hone--relatively speaking. The only difference between the F and UF hones is the surface ground by the company. The hone starts out sufficiently, if not perfectly, flat; and given how hard it is it will remain that way virtually indefinitely so it should not ever be lapped.

Now, on the bright side, your hone has two sides. You have one lapped and one original surface so play with them both!

I wouldn't say that at all, personally. My UF wasn't all that flat and I lapped it with no ill results. As with any very hard stone, surface condition/roughness plays a large role in both cutting speed and resultant finish. The smoother the surface of the stone is lapped, the slower and more finely it will cut.

But it is not a stone. It is a ceramic hone and its ability to cut comes from the ground surface. If someone wants a smoother surface they'd be better off using a piece of glass

If someone gets one that is not flat, they can exchange it for one that is, as the company guarantees them to be flat.

Terminology aside, it is used to hone - therefore it can be called a hone, a (synthetic) stone or whatever one might choose to call it. The ability to cut comes from the hardness of the material. Glass (silicon dioxide) rates about a 5.5 - 6 on the Moh's scale - the aluminum oxide that the Spyderco UF is made of rates at about a 9.X IIRC. The surface texture only changes the speed of cut and the finish imparted to the workpiece - be that a knife or razor or even a fish hook.

Regarding the flatness, I personally won't often bother sending something back I can fix myself - and with better effect. I'd prefer to KNOW it's flat first time out without waiting a week for a new one, as well as being able to tailor the cut to my preference. You can surface a stone and make it cut faster, or you can surface it so that it cuts slower - neither of which ruins a stone, in my opinion. YMMV, of course.

Perhaps this will help clear things up a bit.

The Spyderco and similar ceramic hones are a single solid piece of ceramic material. Other hones such as the Shapton, Naniwa etc. are also called ceramic hones, but they are made by pulverizing a solid piece of ceramic into tiny (and sharp) shards or pieces. These pieces are then graded and mixed with a much softer binder and molded back into hone shaped blocks. This is also why they can assign a grit to their hones, the shards, pieces, grains or grit (chose your term) are graded by size.

Ceramics and glass are made from very fine minerals that are fired until they become a homogeneous mix and then are allowed to cool until solid. The Spyderco type hones, being a single solid piece of extruded ceramic material, is then cut and surfaced into a cutting tool. The pattern on the face of such a hone is like a file, only much finer of course, and that's what gives it the cutting action.

The coarser gray or brown Spyderco does have more of a grain to it... the minerals used to create it are much less fine and so they begin to have an impact on the cutting of steel.

Surfacing solid ceramic hones like the UF Spyderco removes the purposeful pattern ground into the hone, but depending on what kind of diamond plate or method you used, it might still be useful. Surfacing a Shapton/Naniwa type hone dislodges the surface grit and binder to reveal new layer of sharp shards of ceramic in it's binder.

As for the less than perfect flatness of a Spyderco... remember these are made for honing pocket knives... not straight razors, and so there is no concern given to their use for honing razors by the manufacturer.

I do have some solid ceramic hones I use for wood carving knives, but I don't really find them useful for razors.


Regards

Christian

Yes; again, the stone-shaped object in question can be surfaced in manners that allow it to cut in many ways. Be they fast or slow, fine or coarse. Diamond plate lapping is not a good method to get much cutting action on this hone - the surface needs a little texture to get a bite - just like most any other abrasive. SiC loose grit is preferable - and it needs to be refreshed often or it will tend to do too much smoothing as well.

As I said I lightly flattened one side of my U.F. As it had a hump in the middle. Hardly touched it with a 600 grit diamond hone. This morning I got out a Morley Clover brand 6/8" Barbers notch razor that I had a hard time getting a good edge on. I had set a good bevel with my 1000 king then did 50 rounds on the 6000 side. Went to my Coti. for 50 rounds then did100 rounds on my brand new U.F. Spyderco. Edge looked great so I did 30 rounds on my paddle strop with CROX then 30 rounds on the naked side of the paddle leather. One of the best shaves I have ever had PERIOD! My U.F. Took the edge to a new level. I may be all wrong but it seems that what I did to the hone did little to know damage to it.
So far I am a happy camper with my U.F. Spyderco & plan to use & grow with this great hone. Merry Christmas & a Happy & safe New Year!

Slawman

I sincerely doubt you are wrong, using a diamond grit hone to flatten it will put new grooves in the surface and as it worked for you, then great!

The problem with this is that it is unpredictable, it depends on the diamond plate used, for example how much have the diamonds been worn before being used on the ceramic hone. A well worn DMT for example, might cut and flatten the ceramic, but the diamonds might burnish more than cut grooves, leaving the ceramic surface entirely different and perhaps ineffective. It is due to this unpredictability that we can't recommend doing this as the results will vary from user to user.

Regards

Christian