Thread: What is the Sp Gr of Your Best Arkansas Stone

If you were doing a scientific treatise on specific gravity and were trying to correlate it to hardness you would be in big trouble. Diamond has a S.G of around 3.4 or so and the main ore of lead (Galena) has one of around 7.5 or so. The lead has a hardness of about 1.5 and Diamond, well you know.

The basic properties that give a high S.G are usually quite different from those that make it hard.

Originally Posted by thebigspendur

If you were doing a scientific treatise on specific gravity and were trying to correlate it to hardness you would be in big trouble. Diamond has a S.G of around 3.4 or so and the main ore of lead (Galena) has one of around 7.5 or so. The lead has a hardness of about 1.5 and Diamond, well you know.

The basic properties that give a high S.G are usually quite different from those that make it hard.

Dang! Just when I thought I understood!

Originally Posted by thebigspendur

If you were doing a scientific treatise on specific gravity and were trying to correlate it to hardness you would be in big trouble. Diamond has a S.G of around 3.4 or so and the main ore of lead (Galena) has one of around 7.5 or so. The lead has a hardness of about 1.5 and Diamond, well you know.

The basic properties that give a high S.G are usually quite different from those that make it hard.

But it is not designed for that purpose, so you would be a bit foolish to use it in that way.

Dave's post on the previous page sums it quite succinctly, it is to highlight differences within the same group when used by people like Dan, to determine differences etween a group of novaculites.

Bearing in mind that each mineral has a specific mass that does not correlate with any other mineral should make us wary of using it to debate the virtues of apples as opposed to oranges, let alone write a treatise based on the folly of doing so.

Regards,
Neil

.....orapples????

Originally Posted by sharptonn

.....orapples????

...pineberries...

What neal said. When you're comparing novaculite to novaculite, it's a pretty good indicator (not of hardness, but fineness due to lack of open space in the stone matrix). When you're comparing diamonds to novaculite, it's ...well, I don't know what it is.

Originally Posted by DaveW

I would've guessed the dans black that I have and the dans trans were my two most dense stones if I had to guess just based on what the razor is like coming off of them, but they are, IIRC, 2.7 SG or so, and my densest is the dark trans that Natural whetstone sells as "black trans".
.

Good news for me as I have the trans Black for natural whetstone

Originally Posted by DaveW

2.84 is definitely way into the density range for the true hard/black/translucents and has plenty of potential. hard arks are so variable that from that point, it really comes down to how you condition the stone and how you use it and maintain it.

Now the real question whats the best way to condition and maintain it

Use something that's flat and made of hardened steel to break in the surface until it feels like it is almost not cutting and putting a good polish on hardened steel. Any inexpensive hardware store chisel or plane iron would be fine for the task. If you have good hard knives, you could also use them to do the breaking in.

And importantly, keep the surface clean of anything foreign once it's clean. Anything foreign will become a scratch and possibly a chip on a razor that crosses it.

I had never heard of specific gravity before this thread. I'd like to know the sg of my arks, coticules but I'm not going to go through the learning curve to do the requisite test. I don't want to know that badly. If it turned out that the test reflected I had a 'good' stone, I'd be a happy camper. Then again, it could turn out is was otherwise, according to the sg. I'm satisfied with the 'rubber meets the road' test. Honing razors/knives on the darn things. Not knocking the concept of the finding the sg of your stones. I think it is a cool idea, if I knew how to do it, and if it was easy, I probably would.

Definitely no reason to check SG on a hone that you're happy with. The standards are probably there centuries old because the original sellers would sell soft stones as hard to get a higher price, etc, same as folks would shave silver off of quarters.

It's just another point if interest once you have stones now to see how the different SG stones behave, but it doesn't prove anything unless someone starts doing a data sample of substantial size.

I do think it's conclusive if someone orders a true hard ark, they think it's a bit coarse, and find that their stone does not meet government spec or dan's spec. I don't think, though, that anything translucent or solid black will have trouble making the density requirement though, and those are the two types we see a lot of. The lowest I've seen in a stone that passes light is 2.6.