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Question over at SRP
- Thread starter Tok
- Start Date
rtedwards
Active Member
So the interesting part of the original question to me is whether and to what extent the garnets are broken in the process of creating the slurry. Garnets are hard so they aren't easily broken to be sure, but at the scale of an individual garnet, the shear force applied as you scrape one stone against the other is considerable. Thinking of garnets poking up above the softer matrix and being smashed into the garnets poking up out of the other stone, I could certainly argue it either way. One the one hand the impact of the garnets smashing together is sufficient to break up some proportion of them or even most of them, on the other the force is sufficient to pull the garnets intact out of the surrounding matrix and so the slurry is mostly whole garnets. Since most of us observe forces at scales proportional to our hands and bodies, it can be difficult to extrapolate to the world of tiny objects and tiny forces. For example, to things the size of individual sperm or even daphnia in a pond, water is an almost solid substance that is very difficult to move through and has elastic memory. The image of how difficult it is for a sperm to swim to an egg (talking mammals here) is that it would be like a human trying to swim from one end of a swimming pool to the other with his hands tied behind his back and the pool filled with molasses. Motions are completely reversible and inertia is non existent, so as you kicked you legs you would just oscillate back and forth. To swim around in water, bacteria had to invent rotary motors with hairs that act like little propellers, or flagella that operate in non symmetrical motions.
So....we don't really know what proportion of garnets in the slurry are intact or fragmented from theory, we need someone to look at a slurry and report back. I haven't seen any papers that did that so far. I am assuming that to visualize the garnets in the publications they were extracted with means other than a slurry stone. I did a literature search and found 13 citations, but couldn't access many of them and many are written in French. Not many have actual photos of garnets. My French is 45 years old, and truth be told was never very good to begin with, but I haven't seen any description of how the garnets pictured were extracted yet. One paper mentioned viewing them in cross section, but slicing a rock filled with garnets would be a challenge. Generally for this sort of thing you would take a piece of rock and crush it in a mortar and pestle or sonicate to break it apart, which would leave the garnets intact. The purpose of most of the papers I've read is to understand what the composition of the elements of the coticule and surrounding matrix are and explain how they formed. Haven't seen any papers that sought to describe in detail the composition of a slurry created the way we do for honing.
I would think it wouldn't be too hard to see the garnets, if intact, in a slurry although most of the slurry is not garnet, which would obscure things to some extent. They are pretty large and quite within the range of light microscopy. One paper mentions visualizing them with polarizing filters. Spessartine has a pretty high refractive index, so that probably helps with polarized light. We've got some good scopes at work, but none with a polarizing filter set. When I get a chance I'll have a look under phase contrast in the hopes that would work. SEM may actually be a little more challenging because the sample prep tends to make what you are looking for get covered by all the other junk. You could try to separate out the garnet by centrifugation to clean it up, it has a pretty high specific gravity. But you might also separate out the shards if in fact it is broken up by the slurry creation.
This is an interesting question to me, I have a mental model of how honing with slurry versus on water works (much like Bart's visualization) but there can be a huge difference between our heuristic models and reality, and although it doesn't matter for the practice of honing, it is just interesting to me. I had a friend in Australia who made the best bread I'd ever eaten. For her there was a magical life force that existed in the special biodynamic wheat flour and special salt harvested in the UK using ancient methods of the druids or something. She didn't use yeast, it was evil. She would leave the dough out on her counter overnight while the life force grew and she would knead and bake the bread the next day. Delicious. Having a background in microbial ecology, I tried to explain to her that the life force was wild yeasts and bacteria settling out from the dust in her house and that was how the original sour dough starters were created and in fact there was no magic, aside from the magic of microbiology, involved. She wasn't having any of that BS. But you know, although I think I had a better theoretical understanding of the biology and chemistry of bread making, her bread was better than any I've ever made in my life. So goes the age old battle between theory and practice......I'm an empiricist mostly myself, but with a craving to understand what is going on as well.
Reading these papers has been fun. One French paper describes a method for purifying the slurry with magnets so that artificial hones can be made using the garnets and a binding matrix. They claim the artificial stones are almost as good as real ones (if my French and google translate aren't leading me astray), hah. Also layers called coticule occur at various locations within the Appalachians and some in the UK, although I haven't seen any claims that razor hones can be made from them.
Edited to add: Oh and yeah, you guys down south can duke it out all you want, but we Alaskans know that the only good reason for the existence of the lower 48 is to keep Mexico and Canada apart and keep Tierra del Fuego from becoming uncomfortably warm in the summer.
So....we don't really know what proportion of garnets in the slurry are intact or fragmented from theory, we need someone to look at a slurry and report back. I haven't seen any papers that did that so far. I am assuming that to visualize the garnets in the publications they were extracted with means other than a slurry stone. I did a literature search and found 13 citations, but couldn't access many of them and many are written in French. Not many have actual photos of garnets. My French is 45 years old, and truth be told was never very good to begin with, but I haven't seen any description of how the garnets pictured were extracted yet. One paper mentioned viewing them in cross section, but slicing a rock filled with garnets would be a challenge. Generally for this sort of thing you would take a piece of rock and crush it in a mortar and pestle or sonicate to break it apart, which would leave the garnets intact. The purpose of most of the papers I've read is to understand what the composition of the elements of the coticule and surrounding matrix are and explain how they formed. Haven't seen any papers that sought to describe in detail the composition of a slurry created the way we do for honing.
I would think it wouldn't be too hard to see the garnets, if intact, in a slurry although most of the slurry is not garnet, which would obscure things to some extent. They are pretty large and quite within the range of light microscopy. One paper mentions visualizing them with polarizing filters. Spessartine has a pretty high refractive index, so that probably helps with polarized light. We've got some good scopes at work, but none with a polarizing filter set. When I get a chance I'll have a look under phase contrast in the hopes that would work. SEM may actually be a little more challenging because the sample prep tends to make what you are looking for get covered by all the other junk. You could try to separate out the garnet by centrifugation to clean it up, it has a pretty high specific gravity. But you might also separate out the shards if in fact it is broken up by the slurry creation.
This is an interesting question to me, I have a mental model of how honing with slurry versus on water works (much like Bart's visualization) but there can be a huge difference between our heuristic models and reality, and although it doesn't matter for the practice of honing, it is just interesting to me. I had a friend in Australia who made the best bread I'd ever eaten. For her there was a magical life force that existed in the special biodynamic wheat flour and special salt harvested in the UK using ancient methods of the druids or something. She didn't use yeast, it was evil. She would leave the dough out on her counter overnight while the life force grew and she would knead and bake the bread the next day. Delicious. Having a background in microbial ecology, I tried to explain to her that the life force was wild yeasts and bacteria settling out from the dust in her house and that was how the original sour dough starters were created and in fact there was no magic, aside from the magic of microbiology, involved. She wasn't having any of that BS. But you know, although I think I had a better theoretical understanding of the biology and chemistry of bread making, her bread was better than any I've ever made in my life. So goes the age old battle between theory and practice......I'm an empiricist mostly myself, but with a craving to understand what is going on as well.
Reading these papers has been fun. One French paper describes a method for purifying the slurry with magnets so that artificial hones can be made using the garnets and a binding matrix. They claim the artificial stones are almost as good as real ones (if my French and google translate aren't leading me astray), hah. Also layers called coticule occur at various locations within the Appalachians and some in the UK, although I haven't seen any claims that razor hones can be made from them.
Edited to add: Oh and yeah, you guys down south can duke it out all you want, but we Alaskans know that the only good reason for the existence of the lower 48 is to keep Mexico and Canada apart and keep Tierra del Fuego from becoming uncomfortably warm in the summer.
Bart
Well-Known Member
As always, as highly engrossing post, Rick.:thumbup:
There isn't much for me to add. You are of course correct. Taking a decently educated guess (the hardness of the garnets, the fact that they don't show cleavage), we can expect to find intact garnets in a slurry, but without actual observation, there is no way to be sure. You are also correct that the available scientific publishings all mainly focus on the geological and mineralogical properties and mysteries of Coticule rock, and at best only tangentially mention the technological use as sharpening stone. I don't know any single studies that focused on the abrasive aspects of Coticule rocks and their use as a sharpening stone. I also think, that unless we at Coticule.be manage to do some research, it is unlikely to happen.
I do have some pictures of garnets in a book (copyrighted, hence I just can't go ahead to scan and publish them here). On these pictures the garnets are intact, but there is no information stated about how the sample was prepared for the picture.
Kind regards,
Bart.
There isn't much for me to add. You are of course correct. Taking a decently educated guess (the hardness of the garnets, the fact that they don't show cleavage), we can expect to find intact garnets in a slurry, but without actual observation, there is no way to be sure. You are also correct that the available scientific publishings all mainly focus on the geological and mineralogical properties and mysteries of Coticule rock, and at best only tangentially mention the technological use as sharpening stone. I don't know any single studies that focused on the abrasive aspects of Coticule rocks and their use as a sharpening stone. I also think, that unless we at Coticule.be manage to do some research, it is unlikely to happen.
I do have some pictures of garnets in a book (copyrighted, hence I just can't go ahead to scan and publish them here). On these pictures the garnets are intact, but there is no information stated about how the sample was prepared for the picture.
Kind regards,
Bart.