Arkansas Stone ID

I'm not so good on arks. I have an old norton trans and a pocket stone or two from my pops. I got this thing today and it's harder than I expected. Almost harder than my plain green CF. It killed my DMT the rest of the way, now I have an excuse to grab an Atoma.




Cuts pretty dark fast and the color had me thinking soft/washita but its pretty hard. I haven't done the flashlight thing yet. I don't have any of those to compare it to though, compared to the trans its a lot softer but much harder than the hardest slates. Still trying to get it flat so will have to report back on razor use. Was bigger than I expected at 8" x 2" x 1", and technically vintage since they are not in production any more.

Anyone have an idea just from looking?

Arks are never soft. Even washita's are almost as hard as trans. The difference is the washita's are friable. It's basically the same material in a more open matrix. Take a heavy tool and hone it. Easiest way to tell how fast and what "grade" of ark you've got. If it really bites, You've got a washita... all the way down to hard arks which feel like they just barely brush at the steel of the tool.

Looks like a soft; but the only way to tell is by checking the specific Gravity. You can do this if you have a kitchen scale that reads in grams. Then check Dan's for info on which S.G. determines the stones grade. http://www.danswhetstone.com/stone_grades_101.htm
The S.G. table is at the bottom of this page. Hope this helps. Let me know if you have any questions.
Regards,
John

He'd also need a beaker big enough to completely submerge the stone and graduated to 1ml or less.

You don't need a graduated vessel at all since you are weighing the displaced volume of water with the scale. You just need to zero the scale with the filled water container on it. I use a plastic leftover food storage container, Rubbermade, tupperware, or what have you, that is big enough to hold the stone and water. You could use a glass or metal baking pan as well.
Do it just like in the video.

Also since the stone is rectangular you can easily find the volume by measuring the length, width and height in cm.
Then divide the mass of the stone in grams by the volume.
For example:Let's say the stone has a mass of 260 grams. The dimensions of the stone are 10cm x 5 cm x 2 cm; the stone has a volume of 100 cm3. Now divide the mass by the volume. 260/100 = 2.6 S.G = 2.6 which makes it a hard Arkansas.

I usually just use the scale and displacement method as shown in the video since it's easier and I don't have metric rules or calipers and have to convert from English to metric.

Have fun with math!

That is a motley piece. Looks like a Washita/soft Ark. If you are not squeamish about using oil, I'd suggest soaking it in Dan's finest for a couple of days to saturate it, then see how it compares to a smoothed translucent or black hard, checking the results with an ~10x achromatic loupe.

It cuts really well and is glued to the base. It leaves noticeable steel in smiths solution in like 3 minutes of knife honing.