stone types that can be used for polishing/sharpening

[Dabbsterinn]

I imagine a few of us here have some high grit stones for sharpening and polishing and with me being the DIY nut that I am, I've been wondering if I could make my own honing stones, I have used basalt rocks that I just picked up off the ground, dipped in water and got a decent edge with it after using my synthetic no name stone. So naturally I started thinking about how I could improve this but I'm no rock expert, atleast not the mineral type but I know about some rock types found in Iceland, like Jasper, Basalt, some kind of sandstone, what I believe is Catlinite, Dolerite, quartz and Gabbro, has anyone here made or heard of these stones being useful for sharpening? I'm trying to find some very high grit stones so if anyone can tell me how I can tell if it's high grit or not and how I should go about turning the stone into a nice flat whetstone I'd be very grateful

[Jasent]

Interesting idea. Tagging along to hear any input 

[Frosty]

Unless you have some Seda-metamorphic stone formations in Iceland you aren't likely to find anything suitable for more than coarse grinding. Various coarseness of grain marble makes good sharpening stones. Sandstone makes me think there MIGHT be suitable formations, I'd call a university with a geology department.

Frosty The Lucky.

[JHCC]

There are two basic ways to grind a whetstone flat: against a flat abrasive surface (e.g., wet/dry sandpaper on a sheet of heavy glass or a granite block) or against another piece of the same material. The latter method works surprisingly well, so long as the stone isn't too hard. I've used it myself to flatten chunks of the local sandstone. It also has the advantage that you don't need to worry about stray bits of coarser grit getting embedded in the surface and scratching up your workpiece. 

[Glenn]

Do not forget the pieces of broken grinding wheel are still good abrasives.

[ThomasPowers]

A famed sharpening stone was novaculite,   I have a chunk of surgical black that is used only at the very end when you want to literally split hairs.

Most places have a local stone that was used; (Like Whetstone Park in Central Ohio, USA)  However some of the new alloys require super hard stones---diamond hones can be required.

I'd suggest talking with the oldest people you can find about how their Parents and Grandparents used to sharpen things.

Also Roy Underhill's "The Woodwright's Companion" has a chapter on searching out an old whetstone quarry and making a whetstone from it.

Norse leaders from the Viking era and earlier used to have ceremonial whetstones that they carried as part of their "regalia".

Talking with the University would probably be a good idea for local suggestions, both Geology and History departments.

[Anachronist58]

Don't know if this applies, but a few weeks ago,  I bought a beautiful machete at an estate sale, but the edge was way gone. My brother was struggling to chop 20 years worth vines off a gate when I showed up. About ten minutes on a cinder block, and I had a ferocious edge on that blade.

Robert Taylor

[Smoggy]

It's almost certain you have local rock that is suitable for sharpening stones in various grades, some will be coarser, some will be softer but all will work to some extent on most metals. You want to be looking for stones with regular grit particles and with as few inclusions as possible to give a consistant face. As stated they can be shaped by abrasion on other stones or modern materials or can be cut with abrasive wheels or sometimes even cleft.

Also as Glenn mentions, old broken grinding wheels can provide new sharpening stones. I use broken segments to dress my wheels and in doing so also reshape the fragment into a new stone.

Have you ever seen and old building with a dish in the window sill? Usually a kitcken window or where any trade requiring a sharp knife was required, that's the wear from years of sharpening, often on what ever local stone was used in construction!

[BIGGUNDOCTOR]

To get a flat surface find your local gem and mineral society, and have them cut it on their rock saw. Mine has diamond saws with blades up to 30" diameter, and a 36" flat lap to get it totally flat.

[beammeupscotty]

Contrary to what Smoggy says, it is entirely possible that there are no suitable rocks in Iceland  for making whet stones.  This is because Iceland is essentially volcanic and traditional whet stones are either sedimentary or metamorphic.  Iceland has not been around long enough to have either type of stone.  Novaculite which is what traditional American sharpening stones are made of, (both Washita and Hard Akansas) fall in to this category.  From Wikipedia:

" Novaculite is considered to be highly siliceous sediments and may be a product of the low-grade metamorphism of chert beds."

I am pretty confident that Japanese water stones are also sedimentary.  Again, from Wikipedia"

"The geology of Japan provided a type of stone which consists of fine silicate particles in a clay matrix, somewhat softer than Novaculite. ^[10]

Japanese stones are also sedimentary."

It is possible to make a sharpening stone from just about any piece of rock, but it is not possible to make a GOOD sharpening stone from any old piece of rock.  I think you are better off just buying them.

 

 

[Glenn]

Why not take a piece of metal and try sharpening it on several different types of rocks and surfaces?  Take note of what works and what does not work. Use what works. (grin)

 

[MAD1]

On 6/10/2017 at 8:11 PM, Dabbsterinn said:

I imagine a few of us here have some high grit stones for sharpening and polishing and with me being the DIY nut that I am, I've been wondering if I could make my own honing stones,

Marble!

I find that as we reach a 'Nano Level' below .05, items like Glass, Ceramics, and MINERALS like Marble can even further enhance the edge. I find that after a stropping method after 0.03 nano the edge will grow dull overnight. Why? Our/my edge is so keen gravity will fold it or even a magnet near it? A strop on the last material used for a few stokes will give you an edge as it was , maybe even a shade more. Trust that the steel you are working on is critical. Hardness works against sharpness, Chrome is needed ,vanadium is /should be in the base. I find the Carbon content no less than 0.7 is a minimum (however 14c28n is less than 0.7 (0.62) and still works great. So a Marble slate/flat stone will reach the highest level . Please know that this is a lot of work as you must maintain your angle and you must increase your pressure so lightly you may not know the difference but if you do you may cut yourself and never know it until you move or reach for something nearby.I took a friends 8' kitchen Chef knife to a 0.03 level when He cut a melon as though the knife was the same. My friend sliced through his index finger enough to need medical attention. Same knife dulled to less than average to TOO, MUCH TOO SHARP. Like using a Razor on a melon. So my friends Be careful what you teach to folks who really are not in the same thought or degree of 'The best' Please respond. I am not a metal dude (whatever you call them). I was born with a knife in my hand. 'dorseyltd.com' to show I am not selling or trying to influence anything. I need to learn from YOU. See YA!

[Nobody Special]

The "dish" in the windowsill reminded me.  You can use a broken piece of porcelain to sharpen knives, although you have to be careful not to scratch the blade. Done it a couple of times in a fix.