(A follow up to my universally-admired post about slate).
Unlike slate, sandstone is a sedimentary rock. It has not been transformed by heat and pressure into something new; it is simply compressed sand held together by other stuff, or ‘lithified’ if we want to get technical. But like slate, sandstone has also been used for thousands of years to make things sharper.
This again of course, is because of quartz (gets everywhere eh) - sand, generally, is mostly quartz. Though they might normally be rather larger bits of quartz than we’d find in other whetstones, which would make them particularly suited for grinding, or coarser sharpening work. You can get finer sandstones, just usually they’re coarser.
A month or so ago I found a sandstone that I thought had some potential. I could tell instantly that it was a sandstone because I found it on the beach. (Joke - I have no idea if it’s a sandstone, I think it probably is, but anyone feel free to correct me). It’s quite pretty, got layers n stuff:
And the particles appeared to be very evenly distributed and sized, this is difficult to get a picture of but to my eye the whole thing is basically made from twinkly little bits of sand/quartz:
This evening I thought I’d try it out… going by my tried and tested ‘Tooth Method’ this seemed like it’d be about 800 grit, if it worked at all. Even with Mr. 40-Grit-Sanding-Belt and Little Miss 140-Atoma that wasn’t the easiest of tasks, and took a wee while, but we got there in the end. It isn’t perfect, but enough of it is flat enough for us to try it out:
We’ll be using a cheap Bunka blade that I’ve vinegar-ed the rust off, and which has not a snowflake’s chance in hell of going through any kind of paper:
The stone is hard, it does not slurry easily, and again takes a bit of effort with a diamond plate to get here, which I think looks ok for a working mud:
Now I obviously wasn’t going to bother typing all this out just to say at the end that it was a piece of cr*p which I should’ve left on the beach. So yeah - the stone works well. It’s probably a little finer than my initial guess, maybe around 1k, and it feels nice-ish to use, though not a massive amount of 'feedback'. After maybe five mins or so our Bunka goes easily through newspaper, and will have a fair crack at kitchen towel, though not all cuts were as clean as this:
In summary - I was pretty pleased with it tbh. I’ve had some practice in looking for and using stones, so I was hoping it’d be ok, but it’s the first time I’ve tried or used a sandstone, so really I had no idea. It’s obviously not as quick as a synthetic stone, nor as easy to use, but it’s actually not far off the former - this didn't take long, and it works perfectly well. A fun thing to have!
Lastly- there was one aspect in particular that made me wonder… I assume in a sandstone we’d probably want the bind to be quite hard / solid, otherwise you’re just going to get a load of bits of scratchy sand being released the whole time. But this seems very hard indeed; it feels like sharpening on something quite smooth, and is not really releasing any particles at all afaics. It seems the sharpening is being done solely on what’s in the stone itself rather than the mud I’d raised. Will this mean at some point we’ll just round out, or blunt, the abrasive quality of the quartz in the stone? Or does lapping / slurrying with a diamond plate obviate that problem?
And if anyone wants to have a look at it properly and tell me it’s clearly not a sandstone, and that I’m a complete idiot, here ya go: https://drive.google.com/file/d/13_I32sk3xRxarEdmG6xeAp7kY3wS0Rzz/view?usp=sharing
Unlike slate, sandstone is a sedimentary rock. It has not been transformed by heat and pressure into something new; it is simply compressed sand held together by other stuff, or ‘lithified’ if we want to get technical. But like slate, sandstone has also been used for thousands of years to make things sharper.
This again of course, is because of quartz (gets everywhere eh) - sand, generally, is mostly quartz. Though they might normally be rather larger bits of quartz than we’d find in other whetstones, which would make them particularly suited for grinding, or coarser sharpening work. You can get finer sandstones, just usually they’re coarser.
A month or so ago I found a sandstone that I thought had some potential. I could tell instantly that it was a sandstone because I found it on the beach. (Joke - I have no idea if it’s a sandstone, I think it probably is, but anyone feel free to correct me). It’s quite pretty, got layers n stuff:
And the particles appeared to be very evenly distributed and sized, this is difficult to get a picture of but to my eye the whole thing is basically made from twinkly little bits of sand/quartz:
This evening I thought I’d try it out… going by my tried and tested ‘Tooth Method’ this seemed like it’d be about 800 grit, if it worked at all. Even with Mr. 40-Grit-Sanding-Belt and Little Miss 140-Atoma that wasn’t the easiest of tasks, and took a wee while, but we got there in the end. It isn’t perfect, but enough of it is flat enough for us to try it out:
We’ll be using a cheap Bunka blade that I’ve vinegar-ed the rust off, and which has not a snowflake’s chance in hell of going through any kind of paper:
The stone is hard, it does not slurry easily, and again takes a bit of effort with a diamond plate to get here, which I think looks ok for a working mud:
Now I obviously wasn’t going to bother typing all this out just to say at the end that it was a piece of cr*p which I should’ve left on the beach. So yeah - the stone works well. It’s probably a little finer than my initial guess, maybe around 1k, and it feels nice-ish to use, though not a massive amount of 'feedback'. After maybe five mins or so our Bunka goes easily through newspaper, and will have a fair crack at kitchen towel, though not all cuts were as clean as this:
In summary - I was pretty pleased with it tbh. I’ve had some practice in looking for and using stones, so I was hoping it’d be ok, but it’s the first time I’ve tried or used a sandstone, so really I had no idea. It’s obviously not as quick as a synthetic stone, nor as easy to use, but it’s actually not far off the former - this didn't take long, and it works perfectly well. A fun thing to have!
Lastly- there was one aspect in particular that made me wonder… I assume in a sandstone we’d probably want the bind to be quite hard / solid, otherwise you’re just going to get a load of bits of scratchy sand being released the whole time. But this seems very hard indeed; it feels like sharpening on something quite smooth, and is not really releasing any particles at all afaics. It seems the sharpening is being done solely on what’s in the stone itself rather than the mud I’d raised. Will this mean at some point we’ll just round out, or blunt, the abrasive quality of the quartz in the stone? Or does lapping / slurrying with a diamond plate obviate that problem?
And if anyone wants to have a look at it properly and tell me it’s clearly not a sandstone, and that I’m a complete idiot, here ya go: https://drive.google.com/file/d/13_I32sk3xRxarEdmG6xeAp7kY3wS0Rzz/view?usp=sharing
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