How much water fits into a stone?

[Michi]

A while ago, when I sharpened, I looked at the bubbles coming out of the stones and thought to myself "that's a lot of bubbles, how much water is actually being absorbed?"

I decided to find out. The stones I used were all from Suehiro:

• Cerax 1000 (2020 model, double thickness)
• Cerax 3000
• Rika 5000.

I measured the stones so I could work out the volume, and weighed them dry:

• Cerax 1000: 735 ml, 1574 g
• Cerax 3000: 337 ml, 719 g
• Rika 5000: 337 ml, 671 g

All three of them are around twice the density of water.

I left the stones to soak until there were definitely no bubbles coming out. (It took nearly an hour; I left them in the water for an extra 15 minutes after the bubbles stopped.)

Weight after taking them out and lightly drying them off:

• Cerax 1000: 1822 g
• Cerax 3000: 851 g
• Rika 5000: 812 g

By volume, the amount of water absorbed was:

• Cerax 1000: 34%
• Cerax 3000: 39%
• Rika 5000: 41%

I think we should all demand a refund from the places we buy stones from. Because well over a third of what we pay for is air

The other thing that is surprising is how long it takes for all the water to get out of the stones again. I left them outside (in the shade) for several days, with a breeze going for much of the time. (This is at 33 ºC temperature or so; it's summer here. Clothes hung up on the clothes line dry in well less than an hour.)

It was quite amazing how cold the stones were when I touched them. Much colder than ambient temperature. (I had a stone that I haven't used for months—and was definitely completely dry—as a control sitting alongside. The stones I had soaked were a lot colder than the control.) I guess that's testament to how well evaporative cooling works.

After a week of having been out of the water, the stones still aren't back to their original weight. It looks like it will take three or four weeks for them to dry out completely.

 

[Mucho Bocho]

Michi, Are you a professor? You have such a clean logical thought process. I'm thinking you need to change your user name to something like "Mr Scientific Method" or something like that. Thanks for the data and experiment. Look forward to many more. Seriously, you add a lot of substance to this forum and we all benefit form your advise.

 

[Matus]

I did some mesurements some time back with some of my soaking Gesshin stones and also came up with values around 100ml (g) of ABsorbed water per stone. And yes - drying is a thermodynamic process and it cools the stones the same way a hand drier feels 'cold' when it blows hot air on your wet hands. And yes - drying stones like these can take about a week. Just another reason to permasoak them (if OK for the stone)

 

[Michi]

Michi, Are you a professor?

Nope

I've been an invited lecturer at a few universities, but I'm not an academic. I'm a software engineer. (A "hacker", if you like—in the good sense of the term.)

You have such a clean logical thought process. I'm thinking you need to change your user name to something like "Mr Scientific Method" or something like that. Thanks for the data and experiment. Look forward to many more. Seriously, you add a lot of substance to this forum and we all benefit form your advise.

Thank you, I much appreciate the compliment! I'm just curious about how stuff works. When I'm interested in something, and it's not too complicated, I try to find out what's going on. This wasn't a difficult experiment. All I needed was a tape measure and my kitchen scales. Ah, yes, plus a sink full of water

By the way, the scientific method rocks!

 

[Ruso]

Not a metric ton? Bwah - what a disappointment.

P.S. Thanks for testing it though.

 

[MrHiggins]

Michi, Are you a professor? You have such a clean logical thought process. I'm thinking you need to change your user name to something like "Mr Scientific Method" or something like that. Thanks for the data and experiment. Look forward to many more. Seriously, you add a lot of substance to this forum and we all benefit form your advise.

I've enjoyed your posts, too, Michi. Keep up the good work.

 

[masibu]

I started collecting similar information for myself a few years ago to help determine whether to splash n go or to soak stones (and for how long). It can take a very long time for some stones to dry out completely and I too noticed how cold some stones feel even after a week. Some stones such as naniwa's green brick I've seen recommended as a soaking stone but I noticed only a ~20g or so increase in weight after soaking for a few hours which is nothing for such a big stone.