Problem child

[ErieSurfer]

The coticule pictured below is the hardest I've come across. It's flat, but the surface texture is very aggressive and I'd like to tame it a bit. This stone has the highest garnet content of the 4 coticules I own. I've ran it through wet/dry sandpaper from 400 to 1500 grit, and nothing seems to mellow it out.

I've got some loose 1700 SiC powder, but l can't do that kind of lapping indoors and I won't be able to get outdoors until the temp goes above 50F later this spring. I think I have two options - wait for spring or invest in some new diamond plates.

I'm open to ideas...

 

[Empire straights]

The coticule pictured below is the hardest I've come across. It's flat, but the surface texture is very aggressive and I'd like to tame it a bit. This stone has the highest garnet content of the 4 coticules I own. I've ran it through wet/dry sandpaper from 400 to 1500 grit, and nothing seems to mellow it out.

I've got some loose 1700 SiC powder, but l can't do that kind of lapping indoors and I won't be able to get outdoors until the temp goes above 50F later this spring. I think I have two options - wait for spring or invest in some new diamond plates.

I'm open to ideas...

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Kitchen knife, dry, as long as it's flat. If not you'll see.

 

[Empire straights]

Those aggressive ones are the good one imo. I don't usually finish on one, though sometimes I do. I've got a 1x1x2.75" piece that is that way. It's awesome.

 

[Gamma]

Aggressive - meaning the striations are too deep?
Or aggressive meaning the stone is too fast?
What is the actual honing hurdle?
A faster stone is not necessarily coarser. Faster stones are sometimes not actually coarser but still not capable of developing the finest edges due to other factors. There are coarser coticules, sure, but most are not problematic past their need for specific techniques to achieve shaving edges. Then there are some Cotis that are 'tool grade' - not good for razors; but I have only read about them, never had one in my hand.
Garnet concentration can be higher when the garnets are smaller. Often, with natural stones or even synth water stones, increased particle density makes things finer.
With w/d paper - 1000x w/d has more SIC granules per sq inch than 400x w/d does.
What do your blade's scratch patterns look like?
I usually lap with a worn diamond plate, maybe up to 400x. Never higher and my sample size is significant.
If your stone is cutting too deep, maybe try buffing the working surface with a BBW or a 1k-3k synth. Making a lot of slurry for a while and rinsing it off - several times, will do the same thing.
Adjustments to lapping and honing techniques can alter perceptions about the stone's personality too.

 

[ErieSurfer]

Aggressive - meaning the striations are too deep?
Or aggressive meaning the stone is too fast?
What is the actual honing hurdle?
A faster stone is not necessarily coarser. Faster stones are sometimes not actually coarser but still not capable of developing the finest edges due to other factors. There are coarser coticules, sure, but most are not problematic past their need for specific techniques to achieve shaving edges. Then there are some Cotis that are 'tool grade' - not good for razors; but I have only read about them, never had one in my hand.
Garnet concentration can be higher when the garnets are smaller. Often, with natural stones or even synth water stones, increased particle density makes things finer.
With w/d paper - 1000x w/d has more SIC granules per sq inch than 400x w/d does.
What do your blade's scratch patterns look like?
I usually lap with a worn diamond plate, maybe up to 400x. Never higher and my sample size is significant.
If your stone is cutting too deep, maybe try buffing the working surface with a BBW or a 1k-3k synth. Making a lot of slurry for a while and rinsing it off - several times, will do the same thing.
Adjustments to lapping and honing techniques can alter perceptions about the stone's personality too.

Yes, the striations are too deep. To the hand, the surface of the stone feels similar to 600 (worn) - 1000 grit (new) sandpaper.

When I wrote about the garnet content in this stone, it was not because I was able to size and count garnets in a defined surface area. I simply looked at each of my 4 coticules with a illuminated Carson Microbrite 60-120x. This stone was unique because the overall amount of light reflected back to my eye was noticeably greater than the other 3. It's not very scientific, and might be explained by the stone's surface texture.

I've ordered a new USB microscope and a few different loupes but I'm waiting on delivery. I can share images and more informed observations once I have those resources on hand.

I've got Venev bonded diamond stones up to 1200 grit on hand, but I've hesitated to use them for lapping stones. They work fine for knives, but I'm not sure how the binder would respond to coticule lapping. I've got some SiC and AlOx stones, but I would have to confirm their flatness before using them.

I did attempt to rub coticule-to-coticule yesterday, and it worked nicely between the other three coticules, but that got me nowhere with the problem child. It didn't occur to me to rub it with BBW. I'll give that a shot later today.

I lap stones on tempered glass for both loose SiC and sandpaper. I had given up on lapping the stone on sandpaper yesterday, when I did something new. I had a new unused piece of glass on hand, and I simply rubbed the stone on the glass with diluted dawn soap for lubricant. The stone self-slurried so fast that I had to constantly dilute the working surface. It was like doing dilucot lapping. The stone was not impressed.

 

[Empire straights]

Yes, the striations are too deep. To the hand, the surface of the stone feels similar to 600 (worn) - 1000 grit (new) sandpaper.

When I wrote about the garnet content in this stone, it was not because I was able to size and count garnets in a defined surface area. I simply looked at each of my 4 coticules with a illuminated Carson Microbrite 60-120x. This stone was unique because the overall amount of light reflected back to my eye was noticeably greater than the other 3. It's not very scientific, and could probably be explained by the stone's surface texture.

I've ordered a new USB microscope and a few different loupes but I'm waiting on delivery. I can share images and more informed observations once I have those resources on hand.

I've got Venev bonded diamond stones up to 1200 grit on hand, but I've hesitated to use them for lapping stones. They work fine for knives, but I'm not sure how the binder would respond to coticule lapping. I've got some SiC and AlOx stones, but I would have to confirm their flatness before using them.

I did attempt to rub coticule-to-coticule yesterday, and worked it nicely between the other three coticules, but that got me nowhere with the problem child. It didn't occur to me to rub it with BBW. I'll give that a shot later today.

I lap stones on tempered glass for both loose SiC and sandpaper. I had given up on lapping the stone on sandpaper yesterday, when I did something new. I had a new unused piece of glass on hand, and I simply rubbed the stone on the glass with diluted dawn soap for lubricant. The stone self-slurried so fast that I had to constantly dilute the working surface. It was like doing dilucot lapping...

Id take that sucker and give a rub down on a hard ark. Don't you have a big translucent? I've got a couple that had to take that path. I did a really rough Tam O'shanter on a fine India to flatten it the buffed it on a hard ark. It might work, that hard novaculite is pretty tough stuff. It could give you an idea what size grit it shedding too.

 

[ErieSurfer]

Is take that sucker and give a rub down on a hard ark. Don't you have a big translucent? I've got a couple that had to take that path. I did a really rough Tam O'shanter on a fine India to flatten it the buffed it on a hard ark. It might work, that hard novaculite is pretty tough stuff.

Yes, I've got a big translucent. I guess it would be pretty hard to ruin it. I didn't think of that yesterday...

 

[Empire straights]

Yes, I've got a big translucent. I guess it would be pretty hard to ruin it. I didn't think of that yesterday...

Yeah I thought you had a real big, pretty one. I dropped my primitive cut one about 4 months ago and it bounced. Didn't chip or anything. I don't know if quartz>garnet but I bet they'll break eachother down some.

 

[cotedupy]

I'd be happy that you've got a coarse, fast, aggressive coticule! I have one that is very unlike any other coticule I've ever had; it's a superb stone, but couldn't really finish anything higher than about 2 or 3k.

My initial impressions sound exactly like yours:

Coticule love... show off your rock

I must have mixed them up. I'm not particular about what we call them, I like those rocks.

www.badgerandblade.com

Though they don't look very similar. Mine has a very dark and equally coarse BBW layer:

Coticule love... show off your rock

I must have mixed them up. I'm not particular about what we call them, I like those rocks.

www.badgerandblade.com

 

[ErieSurfer]

I'd be happy that you've got a coarse, fast, aggressive coticule! I have one that is very unlike any other coticule I've ever had; it's a superb stone, but couldn't really finish anything higher than about 2 or 3k.

My initial impressions sound exactly like yours:

Coticule love... show off your rock

I must have mixed them up. I'm not particular about what we call them, I like those rocks.

www.badgerandblade.com

Though they don't look very similar. Mine has a very dark and equally coarse BBW layer:

Coticule love... show off your rock

I must have mixed them up. I'm not particular about what we call them, I like those rocks.

www.badgerandblade.com

I get your point, but I thought it was going to be some version of awesome coticule for finishing work.

It was in a mixed auction lot, and the pictures from the seller were not great. My estimate of the shape and size seemed encouraging.

Then I received the lot and I got more excited about this stone when I read the words, "Made in Belgium" stamped on two sides. There was no lid to the paperboard box, but given the stone's dimensions and appearance, I thought it would be some version of Old Rock/Deep Rock/Salm. I ignored it for a few weeks, knowing that it needed some inspection and lapping. Yesterday was the day for that work.

I may need to adjust my thoughts about this stone and what I expect it to do for me. I'm eager to receive the microscope and loupe shipment...

 

[ables]

I get your point, but I thought it was going to be some version of awesome coticule for finishing work.

It was in a mixed auction lot, and the pictures from the seller were not great. My estimate of the shape and size seemed encouraging.

Then I received the lot and I got more excited about this stone when I read the words, "Made in Belgium" stamped on two sides. There was no lid to the paperboard box, but given the stone's dimensions and appearance, I thought it would be some version of Old Rock/Deep Rock/Salm. I ignored it for a few weeks, knowing that it needed some inspection and lapping. Yesterday was the day for that work.

I may need to adjust my thoughts about this stone and what I expect it to do for me. I'm eager to receive the microsco pe and loupe shipment...

That looks alot like one of mine! That shadow on yours is some of the blue layer within the yellow and Id been wondering what it would look like when lapped to. I have 3 old ~2x4 barber sized coticules, they are so much faster at steel removal than my new coticules. Both the ones pictured function very similarly. Ive used them to take small chips out and set bevels on very dull razors in maybe 10 minutes to my shock. Just chewed threw a Spike wedge and a Sheffield steel I recall. Almost as fast as a Shapton 2k, my normal starting point.

Even being so fast I can create a good sharp shaving edge, not my best, but acceptable and safe. I believe back in the day the best coticules were probably the fastest all around hones and not the buttery smooth finishers. I think "Adjusting your thoughts" is the right idea. Instead of a super fine finisher stone I like to think of mine as true one stone pocket razor hone. And am happy to have them after I about drove my self nutty when I started out using new coticules with very little abrasivness and silky smooth. Old timers would of tried my new la grise? and got too frustrated if trying to wrangle a razor really out of wack. I had at one point become so frustrated I was going to get rid of mine and never use a coticule again. I just didn't realize the vast differences in coticules.

To get the most out of it I would make sure the surface is fully smoothed, use a knife or slurry stone. Absolutely no remaining lap marks. Work slurry dilution, might need to do multiple cycles. Then try: Just water, running water, dry and if still not happy just use oil. I love my little stones and can really "Zen out" honing on them, they speak to me very well.

Even though I have shaved many times off mine I rarely can resist another finer hone after a few shaves. Needs smoothing out? Silky la grise? coticule or thuri. Needs some more bite? Arkansas or maybe fine diamond paste for me.

 

[ErieSurfer]

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That looks alot like one of mine! That shadow on yours is some of the blue layer within the yellow and Id been wondering what it would look like when lapped to. I have 3 old ~2x4 barber sized coticules, they are so much faster at steel removal than my new coticules. Both the ones pictured function very similarly. Ive used them to take small chips out and set bevels on very dull razors in maybe 10 minutes to my shock. Just chewed threw a Spike wedge and a Sheffield steel I recall. Almost as fast as a Shapton 2k, my normal starting point.

Even being so fast I can create a good sharp shaving edge, not my best, but acceptable and safe. I believe back in the day the best coticules were probably the fastest all around hones and not the buttery smooth finishers. I think "Adjusting your thoughts" is the right idea. Instead of a super fine finisher stone I like to think of mine as true one stone pocket razor hone. And am happy to have them after I about drove my self nutty when I started out using new coticules with very little abrasivness and silky smooth. Old timers would of tried my new la grise? and got too frustrated if trying to wrangle a razor really out of wack. I had at one point become so frustrated I was going to get rid of mine and never use a coticule again. I just didn't realize the vast differences in coticules.

To get the most out of it I would make sure the surface is fully smoothed, use a knife or slurry stone. Absolutely no remaining lap marks. Work slurry dilution, might need to do multiple cycles. Then try: Just water, running water, dry and if still not happy just use oil. I love my little stones and can really "Zen out" honing on them, they speak to me very well.

Even though I have shaved many times off mine I rarely can resist another finer hone after a few shaves. Needs smoothing out? Silky la grise? coticule or thuri. Needs some more bite? Arkansas or maybe fine diamond paste for me.

Yep, I'm with you. I've thought for years that all coticules were finishers, and that some were better at that task than others. I hadn't really considered the idea that a more aggressive coticule could be an asset. But then, I never had my hands on an aggressive coticule...

Live and learn, right?

 

[cotedupy]

I get your point, but I thought it was going to be some version of awesome coticule for finishing work.

It was in a mixed auction lot, and the pictures from the seller were not great. My estimate of the shape and size seemed encouraging.

Then I received the lot and I got more excited about this stone when I read the words, "Made in Belgium" stamped on two sides. There was no lid to the paperboard box, but given the stone's dimensions and appearance, I thought it would be some version of Old Rock/Deep Rock/Salm. I ignored it for a few weeks, knowing that it needed some inspection and lapping. Yesterday was the day for that work.

I may need to adjust my thoughts about this stone and what I expect it to do for me. I'm eager to receive the microscope and loupe shipment...

Ah, I can certainly understand the disappointment of hoping for an excellent razor hone, and it turning out to be perhaps better suited for knives (my priorities are obviously the other way round!). Even finer coticules are very good knife stones when slurried, and coarser ones are truly superb.

I’ve only had 8 or 10 coticules, but in my experience, the ones that are fine enough to finish a razor are far more common than super aggressive ones. So if this one doesn’t turn out to be the finisher you hoped then you’ll still doubtless find many other more suitable versions in the future .

But in the meantime it sounds like what you’ve got is something a bit uncommon, so definitely hold onto it. In the grand scheme of things; very fine natural stones are two a penny, and coarser or medium grit stones tend to be sandstones, which are sloooooooow. Good, fast, mid-grit naturals are rare. Nice find! (In my opinion anyway )

 

[Gamma]

Light reflected back is often mica content, not always but more often than not it's mica and not garnets.
All that aside though, I understand the issue is a too-deep scratch pattern.
If all else is equal, in comparison to other stones and slurry density, then deeper striations would be larger garnets, or a significant # of whole garnets being jettisoned during honing. A greater number of same-size garnets would not create deeper scratch patterns unless there is a slurry density issue - which is a possibility.
If the stone is loaded with over-sized garnets, it is what it is.
Autoslurrying or a slurry density anomaly might be overcome with honing and slurry technique adjustments.
The stone making slurry while rubbing on glass with soap is a good clue.
I might try the latter steps of honing going uphill under running water, without making slurry.
I have owned several LGB, LPB, LGJ, La Grise and La Verte with the same sort of personality. Horses for courses...