Grit of leather/synthetic

I use the Shapton series from 4k to 30k but - and I know many sharpening purists disagree - I can't obtain a really sharp edge unless I go to .25 diamond.

Abrasive experts claim that the best way to sharpen with diamond paste is to lap the straight on glass. It doesn't work all that well, primarily because there are so many variations in geometry over the length of a blade and because there is no "feel".

So, I have been stropping on leather paddle and hanging strops charged with .25 diamond. Am I defeating the purpose of using .25 diamond on leather because the leather is more abrasive than the paste? Does anyone know the abrasive qualities of leathers, specifically in terms of micron or grit sizes?

I would prefer a synthetic material in which the abrasive qualities are known and consistent, but all of the synthetic strops I have been able to find are backed on wood, which seems counterproductive to me, given wood's tendency to cup, etc. I would think that adhering a synthetic material to a glass plate would be preferable. Can someone recommend a good synthetic material with a known abrasive quality (less than .25 micron)?

I think you will find that leather, if it has any abrasive qualities at all will be far finer than even 0.25 micron paste. One can strop for months on a variety of leather strops and the surface will still remain clean and clear. The same test on 0.25 micron will pretty quickly show residual deposits of metal left on the surface of the strop from the abrasiveness of the paste.

I have not favored synthetics for pastes (and I use this material frequently) as they are not porous and the pastes never seem to stay put well. On porous leather or balsa wood the abrasive becomes embedded right into the surface providing a better base.

I would stick with leather as a better choice over synthetic. There is more to consider with abrasive stropping than just grit size. Rounding of the edge can be an issue with some materials of forms of construction. A hone of course is absolutely rigid so as long as you maintain perfect contact, technically one could never round the edge. Balsa wood would be nearly as rigid as would a firm leather. Sueded leather tend to have a higher napp than can spring back up as the edge passes, in theory rounding slightly as can any form of pasted hanging strop, leather, cloth, felt, etc.... here a light touch and skilled hand makes it a non-issue but something to consider anyway. from time to time I do runs of hanging strops specifically for pastes but do not suggest them as beginner tools.

Tony

Thanks, Tony. I see no advantage to using rough out leathers, then, which will always have a tendency - with no matter how deft a touch - to spring up and round the edge. So why not always use just as dense and hard a leather as one can obtain, since it will always hold enough of a charge to stop with? I see your site is shut down for ordering until the 7th, but are your products available for viewing elsewhere?

Firm leather, pastes on glass, honing films, etc.... would all work well if after a truely rigid format. Even a loom type leather strop would do if tensioned highly enough, just remember to loosen the tension for storage.

I have never been a fan of the wooden slotted 'spring strops" in my experience at least the tension required to actually get some give from one far exceeds normal stropping pressure. If one feels they need the give either the loom type, a felt padded version like one Dovo makes or a hanging strop would do the job well.

Any of the tools will still do a nice job but each of us has their own preferences, right or wrong.

I am working on uploading my New Year's Sneak Peek today of stuff that will be coming up next week. Check back later today to see what is new. Ordering will be dissabled until next week though.

Thanks,
Tony

Hmmm, the grit of leather. Now that is a poser. I wonder, how slick a million grit gizmo would be, or a gigagritter? I'll betcha that leather is about a teragrit, or maybe not; it's a lot slicker than terra firma. :shrug:

:roflmao

Hey Bruce, an Old Sotan like you must have skinned a few white tail or two in your day - heck, there are enough on Ford Parkway to practice on. Even if you don't touch bone, the hide can really dull a blade quickly!

Even though the natural abrasives in hide wouldn't make much difference, the tanning process may leave silica, chromium, or other abrasives in the finished leather. My own microscopic study of leather strops (unpasted) compared with Shapton honed blades reveal that the strop actually 'roughs up" the blade. So why do stropped blades generally shave better for me? No idea.

You should be able to get a really sharp edge off the 4K part of your series, the rest is just making that edge more comfortable to shave with. If you're not you need more practice on setting the bevel on the lower grits before moving up.

It sounds like you're using the pastes as a crutch for inadequate bevel setting.

While there may be some negligible grit to leather I feel that the hundreds of years of strop use as well as the extensive experimentation that goes on with the members here regarding pastes leads me to believe that the grit won't effect anything.