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Softer steel creates more slurry?

kinematic

Well-Known Member
About a week ago I ordered a new chisel at work wich I got yesterday. I immediately ground a new bevel on it because the bevel as supplied is always wrong and afterwards I honed it on my work coticule. The new chisel is less hard than my Nooitgedagt chisels, 60 HRC compared to 62 HRC. The drab my Nooitgedagt chisels leave behind on the stone is almost black wich indicates low amounts of slurry. The new softer chisel however leaves behind a light grey drab wich indicates to me more slurry is formed. I've also seen the same thing happen with my kitchen knives. My hard Japanese knives leave behind an almost black drab while my softer Western knives leave behind a lighter drab. Are the shavings of softer steel simply lighter in colour or do they encourage more slurry to be formed? Has anyone experienced the same thing?
 

Bart

Well-Known Member
I think you're jumping the conclusion that the darker the slurry to less garnets it contains. It's true to some extent, but I don't think it's the only contributing factor to the slurry color. Steel forms several different oxides. The main oxide we see on a hone would be ferrous ferric oxide (Fe3O4), a.k.a. magnetite. It's a type of oxide that forms when iron oxidizes under water.
Other iron oxides may have different colors. We all know the red variant, ferric oxide (Fe2O3) a.k.a hematite.
I'm not sure if an how the other components of steel influence the oxidation process, but I can imagine so.
I too have noticed that different steels tend to cause a different shade of slurry. That's why I always use the same Double Arrow razor to estimate the speed of a Coticule. All that is about to change, when the abrasion tester arrives that the good Ralfson has build to my instructions. It's a device that should allow the objective measurement of abrasive speed.

At any rate, a Coticule is not abraded by the steel, but by its own garnets that are already present in the slurry. That's the big reason why the Belgian Coticule is such a good honing stone. There are more rocks in the world that contain spessartine garnets, even of the correct size, but the binding element must be of the right hardness, to allow a very slow, but steady stream of new garnets being released. If you would transfer slurry to a glass surface, and hone on that, you'd notice that that slurry looses its cutting power after a short time.

It's possible that the released phylosilicates (the binding element in Coticule rock) react chemically with one of the components of the steel (e.g. Chrome, Molybdenum, Manganese, ...) have an influence on the slurry color. I think that's more likely the cause why you see a different shade in your slurry.


PS. It is a public secret that many tool and knife manufacturers overrate the HRC values of their tools. I've come across lab test that measured 58HRC on knives that were advertised as 62 HRC. Just to say that we must approach these claims with caution.

Kind regards,
Bart.
 

Smythe

Well-Known Member
Bart said:
.... If you would transfer slurry to a glass surface, and hone on that, you'd notice that that slurry looses its cutting power after a short time....
Kind regards,
Bart.
There is an 1877 patent for that too... using our very own Coticule (soap stone).

Its a sheet of glass the typical size of a hone mounted on a wooden base with a recess to store the soapstone (a small slurry stone) when not in use.

When ready to sharpen, the soapstone with water is rubbed on the glass surface until slurry (what they call lather) is produced. the razor or other instruments is sharpened upon the glass to produce a smooth, sharp and even edge.
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Bart

Well-Known Member
Smythe,

your eruditeness never ceases to amaze me.

I have tried slurry on glass once, and I didn't like the results at all. Reading the patent makes me somehow doubt my prior conclusion, although I remember a particularly lousy test shave. I've also performed the final stages of "Unicot" on a piece of wet glass one time (a round long drink glass, to be specific). Also that result was nothing to write home about (as we say in Flemish).
Maybe we should give the idea some more credit. On the other hand, I'm starting to think that during the second half of the 19th century, people used to patent every fart in a bottle (another Flemish expression). :D

Kind regards,
Bart.
 

tat2Ralfy

Well-Known Member
My Dear Smythe
I too am never short of amazed by the knowledge that you have about these things, I vote that your label be changed to "Coticule.be Official Historian" :thumbup:

BTW are you that old??
 

Stewart

Active Member
Emmmmm, I love the way the description is written of the glass hone. I found the slurry stone description as being "Soap Stone" a bit puzzling.

I use soap stone to carve japanese and Chinese seals used to sign my calligraphy and other sumi projects. I use other stone as well, such as jade but use soap stone most frequently for some of the smaller "chops" I carve for other folks.

I have a few blanks and a larger one that I could use to try out on a piece of sheet glass I use for lapping some of my stones. Knowing soap stone I can't see the slurry/ lather being able to do much other than possibly polishing the edge some.

Won't take long to set up and try. Something to do over the weekend 

Hope all of the folks celebrating Memorial Day have a safe one and take a minute to remember the reason for the holiday.

Stew
 

Smythe

Well-Known Member
Bart said:
Smythe,

your eruditeness never ceases to amaze me.

I have tried slurry on glass once, and I didn't like the results at all. Reading the patent makes me somehow doubt my prior conclusion, although I remember a particularly lousy test shave. I've also performed the final stages of "Unicot" on a piece of wet glass one time (a round long drink glass, to be specific). Also that result was nothing to write home about (as we say in Flemish).
Maybe we should give the idea some more credit. On the other hand, I'm starting to think that during the second half of the 19th century, people used to patent every fart in a bottle (another Flemish expression). :D

Kind regards,
Bart.
Here is what I think, when the stone is rubbed, some of the garnets cut fine grooves in the surface of the glass and then settle into those grooves, the glass simply presents the abrasive to the blade... a type of sandpaper.

Indeed... people still patent "every fart in a bottle" or as we say where I am from, “anything under the sun”.
in hopes that somewhere, someone may find use for it, or improve on it, and then they'll collect royalties.
 

Smythe

Well-Known Member
tat2Ralfy said:
My Dear Smythe
I too am never short of amazed by the knowledge that you have about these things, I vote that your label be changed to "Coticule.be Official Historian" :thumbup:

BTW are you that old??

Hmmm, that depends… my age fell off the calendar a long time ago and I often don’t remember my birthday :lol:.
Historian... maybe, but as my wife would suggest, I read too many old books.
 

Smythe

Well-Known Member
Stewart said:
Emmmmm, I love the way the description is written of the glass hone. I found the slurry stone description as being "Soap Stone" a bit puzzling.

I use soap stone to carve japanese and Chinese seals used to sign my calligraphy and other sumi projects. I use other stone as well, such as jade but use soap stone most frequently for some of the smaller "chops" I carve for other folks.

I have a few blanks and a larger one that I could use to try out on a piece of sheet glass I use for lapping some of my stones. Knowing soap stone I can't see the slurry/ lather being able to do much other than possibly polishing the edge some.

Won't take long to set up and try. Something to do over the weekend 

Hope all of the folks celebrating Memorial Day have a safe one and take a minute to remember the reason for the holiday.

Stew

Ah… that device would only restore the edge of a razor that was just becoming dull from regular use. Back-in-the-day, razors were (for the most part) “shave ready” out the box – indeed you have seen those vintage razor boxes with the stickers…
“This razor is set ready for use… “
or
“This razor is sharp and ready for shaving……”
Barbers and self shavers, as far as they were concerned, “honing” a razor was maintenance of the edge on a Razor Hone (Barber Hone, Soap Stone (Coticule) or German Water Stone)… in other words they were expected to do a touch-up.

However, if the razor was so dull that a razor hone could not do the job in reasonable time, they would simply send it out to the nearest cutler who would sharpen on a courser stone and then finish on a razor hone.

But “today” nearly a century later, we have a completely different perspective on “honing”. Today, when we think of “honing” a razor, we tend to think about “setting the bevel”… And this is only because “today” most of these razors are antiques, and very dull from disuse (or abuse). No one back-in-the-day would ever use razors in these conditions to shave with… so today we in our shaving community, have all become the “old time cutlers” sharpening our dull antique razors on course hones, and then finishing on razor hones.


Please let us know how that "hone" works out.
 

danjared

Well-Known Member
Smythe said:
But “today” nearly a century later, we have a completely different perspective on “honing”. Today, when we think of “honing” a razor, we tend to think about “setting the bevel”… And this is only because “today” most of these razors are antiques, and very dull from disuse (or abuse). No one back-in-the-day would ever use razors in these conditions to shave with… so today we in our shaving community, have all become the “old time cutlers” sharpening our dull antique razors on course hones, and then finishing on razor hones.

What's worse is that nearly every cutler today couldn't hone a razor to save his life.
 
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