I did try out the bluestone a few years ago, it was really hard and coarse to me. I have never heard of heat treating natural stone, let me know if that works.Pretty sure i also have a couple of that stone. Looks very similar anyway. Have you tried out Pennsylvania bluestone? I think it is mined in the northeast (NEPA to the locals) but is available all over the state. I picked up a large piece from the local landscaping supply. Sandstone, feel like it would be coarser then a queer creek. Slow and course with water but fast and fine with slurry. When the weather gets better i want to put a few pieces in my kiln and heat-treat? them. Read somewhere, grinding and honing i think, that heat will change the characteristics of the stone. I have plenty of it so why not.
Big piece of slate is only 1/4 thick. I am curious to try it also. Got it as a sample.I did try out the bluestone a few years ago, it was really hard and coarse to me. I have never heard of heat treating natural stone, let me know if that works.
Those slates/shales look like they might do the job, and I'm very curious about that x-large newly mined slate.
MM, I would defiantly like to try one out.Thanks guys, I am going to seal a few more up in case anyone wants to try them out. They might not be the brown ones above, but the darker shales/slates that you’ll see in later installments to this thread.
It would be cool to see a video of what it can do and see what the edge looks like under high magnification.MM, I would defiantly like to try one out.
Alx
You put them in the kiln to harden them?Bluestone ready for the kiln
Bluestone ready for the kiln
Some potters “calcine” hard natural stone, which is baking them at very high temperatures to make them more friable so they can break them into dust for glazes. Maybe @Pack line is doing something similar here? Friability is a good thing for jnat grit, but as for making the entire stone friable we’ll see if that’s a good thing.You put them in the kiln to harden them?
I've got a forge and a piece of welsh slate I'd like to be more friable. That's a thought.Some potters “calcine” hard natural stone, which is baking them at very high temperatures to make them more friable so they can break them into dust for glazes. Maybe @Pack line is doing something similar here? Friability is a good thing for jnat grit, but as for making the entire stone friable we’ll see if that’s a good thing.
Warning!!! Some rocks like shales, slates, mudstones, schists, limestones and others can explode when heated to high temperatures! I wouldn't recommend doing this.I've got a forge and a piece of welsh slate I'd like to be more friable. That's a thought.
I wouldn't go real high and that piece of slate is from aj, it was cheap, I don't care if it shatters. Might look cool.Warning!!! Some rocks like shales, slates, mudstones, schists, limestones and others can explode when heated to high temperatures! I wouldn't recommend doing this.
I appreciate the warning. It was the first thing that crossed my mind when i thought about doing it. I have some other projects going that need to be heated so these will probably see a 200F oven to 6-8 hours then a 400F oven before they see the kiln. I don't want anything turning to ceramic either so i won't be going too high. Outdoor project for sure.Some potters “calcine” hard natural stone, which is baking them at very high temperatures to make them more friable so they can break them into dust for glazes. Maybe @Pack line is doing something similar here? Friability is a good thing for jnat grit, but as for making the entire stone friable we’ll see if that’s a good thing.
*Edit* WARNING - Some rocks like shales, slates, mudstones, schists, limestones and others can explode when heated to high temperatures! I wouldn't recommend doing this.
I had a really nice shave off of this hard shale yesterday. The edge was quite comfortable, but not scary sharp. I finished with more slurry than I normally would, so I think there is room for improvement.Here is a piece I just sealed in a batch of stones. It’s hard, and there were a few cracks in the sides that needed sealing with CA before the spar urethane. One of the cracks was sizable and part of it went up across the layers. I thought a slate would split along the layers, so perhaps this is a hard shale. 210 x 60 x 36
I worked up a slurry with a worn atoma 400 and worked that slurry for a while, very slowly diluting it and actually finishing on a thicker slurry than I normally would (compared to a jnat finishing slurry). The shave test will have to wait for a few days.
The point of all of this isn’t so much to find the best razor honing material in existence, or start a hole mining operation. There are a lot of legendary razor hones out there with established reputations. These past few years of rock hunting were a part of a switch in mindset - moving further away from mass production and into local goods and services. At the end of the day I feel better eating a meal with locally grown food, on a plate made by the local potter, at a table I made myself from local wood. Even finding a single rock that can do the job would be amazing, because then they become tools again. This isn’t a flashy Nakayama maruka kiita sports car that I bought just to show it off, this is a rock fine enough to finish a razor, and I found it at the creek.
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