Yet another please identify my hone-thread

[Gsssson]

A friend gave me a razor hone some time ago (black stone, second from the bottom), and I'd like to know what kind of stone it is. I added a number of other fairly well known stones for colour reference, and I did weigh and measure all the loose stones to calculate their density.

From top to bottom:

Washita, density ~2,00 (fairly large margin for error, too small to get the accurate weight)
Smiths Soft Arkansas
Norton Hard Arkansas (Translucent, I'd say), density 2,65
Mystery hone, density 2,80
Escher, thurungian if I'm not mistaken.

The mystery hone is dark grey or black, a bit heavier than the translucent arkansas as the density shows, it used to have remains of a label with the word "razor" or something like that but it was removed by the previous owner. Water does not "wet it", it mostly just gets pushed off the stone by the razor when you draw it across. Worked well with oil (WD40).

I am not skilled at sharpening razors (yet), nor do I have a descent strop or stropping compound. (I'm getting there, sooner or later.) I did however make an attempt to hone a few old razors on the hard arkansas, the escher and the mystery hone, the arkansas and escher did make the razors sharp enough for cutting arm hair, the mystery hone gave a clearly better result - not nearly good enough to shave with it, but I'm guessing that's where a strop would make a big diffrence.

Anyone have an idea what kind of hone it might be?

[Magpie]

Thats a mighty high density there. By looks, I would say a surgical black Ark, but I have never encountered one of that density.

Perhaps it was one of those "For Good Razors" hones? Anybody ever do a density check on theirs?

[Martin103]

From the description and looks I would think it is highly possible that it is in fact a Black Arkansas.
Density Standards
Soft Arkansas**** **********2.20-2.30*** Specific Gravity
Hard Arkansas*********** * 2.30-2.45****Specific Gravity
True Hard Arkansas***** *2.50 +** * ****Specific Gravity
Colored Translucent**** * 2.50 +**** ****Specific Gravity
Black Arkansas************ 2.50 +**** *** Specific Gravity

[RezDog]

How does density get calculaed

[eKretz]

Density is mass/volume. Specific gravity is density of the item under test/density of water. Density of water is near enough 1g/cm³ so for our purposes density and specific gravity are near enough to be called the same.

The highest density possible for an Ark is something like 2.65 or thereabouts - this is the density of pure void-free quartz/SiO2 - what Arks are made of almost 100%. I would like to hear what method was used to arrive at the figures given for the OP's stones. Measuring with a ruler and cheap postal scale will not give accurate numbers.

[doorsch]

Density is mass/volume. Specific gravity is density of the item under test/density of water. Density of water is near enough 1g/cm³ so for our purposes density and specific gravity are near enough to be called the same.

The highest density possible for an Ark is something like 2.65 or thereabouts - this is the density of pure void-free quartz/SiO2 - what Arks are made of almost 100%. I would like to hear what method was used to arrive at the figures given for the OP's stones. Measuring with a ruler and cheap postal scale will not give accurate numbers.

Just calculated yesterday, my Trans Ark was around 2.80 so are you sure Eric? Iam sure i calculated correct....

I also dont think you need a hypercalculated ruler, if youre correct on mm that should do it.

I would vote for surgical Black Ark, not too many other possibilities around...

[doorsch]

Perhaps it was one of those "For Good Razors" hones? Anybody ever do a density check on theirs?

Can do that later if wished, but its a dense slate, iam quite sure its below....

[eKretz]

Yes I'm sure. The only way it could possibly be higher would be if you had a stone with impurities - which is very rare for an Ark. They are usually on the order of 99.5% pure silica. To properly measure density, volume and weight should be measured very closely - digital calipers do nicely - but you need to measure in four places for each dimension and average if the sides aren't parallel. Don't forget that any error in measuring is cubed! This still won't give an accurate measure of volume if the stone is chamfered or if it's porous enough to absorb water. The best way to accurately measure the volume is with a liquid - i.e. water and a burette, but not many have this equipment. Weight to the gram is probably close enough.

I have measured probably 30 hard Arks and never found one over 2.65 S.G.

[doorsch]

Can do that later if wished, but its a dense slate, iam quite sure its below....

Did calculate a Purple La Lune, to prove what unaccury does i took the Values and changed them with reducing around 2mm on one side measurement.....

Normal Calculation
10.1 x 5.1 x 2.1 / 311 gramm = 2.87gr/cm2

Changing values
10.1 x 5.1 x 1.9 / 311 gramm = 3.17 gr/cm2
10.1 x 5.1 x 1.7 / 311 gramm = 3.55 gr/cm2

So the purple Lune fex shows a very high density. Somebody can make a counter measurement on a purple lune?

[Brontosaurus]

One post in. Welcome to SRP. Please introduce yourself further. Density is not the same thing as specific gravity, no? In any case, I'll take the hard Arkansas stone as shown.