Thread: Oozuku tomae

Originally Posted by Srdjan

Christian, I would seal it. Doesn't hurt and doesn't take a lot of time either. Seal the sides completely, seal the bottom along the sides (leave "a hole" in the middle, say around 30% of the surface area). This is a trick I learned from a good friend, who heard it from an experienced Japanese togishi. I suppose it makes sense... lets the stone "breathe", drain water more easily, if any gets trapped inside. It all depends on the hardness of the stone, personal preferences, so as usual, YMMV.

Not to side track this thread. Alex won't steer you wrong. He is great to work with. It is actually a really cool looking stone with the kawa on the back being a plus.
So to my point. I find the above quote about sealing very interesting. I have wondered about this in my head going back and forth. On the one side I find this idea to make perfect sense and thought about doing it. Then on the other side it would also open up the stone bottom to absorb more water in the unsealed area. I thought about it, but in the end I didn't see anyone else doing it that way so I seal the sides and bottom completely. I think one of the main points of sealing is to give the stone more strength and fill in any cracks, but also to stop water up take. In the end as long as the stone doesn't break I guess either way works. Do you see your stones sealed in this manner dry quicker than ones that are fully sealed?

The two I have seen split did so on the side, parallel to the surface, which makes sense since it's a sedimentary rock. Sealing the sides should prevent that. That being said I am with you rideon666, I seal them all the way for a piece of mind. The only one I did just the sides is a small kamisori kiita with the hatanaka stamp that the previous owner lapped the bottom to preserve the stamp.

I do have one that was originally sealed sides and bottom, but I lapped the bottom to use it. Now that side is so hard it doesn't absorb water. Which is why I lapped it. The top is a softer Kiita and the bottom is a hard namazu.

My post wasn't really meant to be instructional, but hopefully it provokes a bit of thought. The main point I guess is, I seal my stones, and I think any stone would benefit from it.

I feel so, because I use mostly vintage stones, with a few exceptions, like when I know for sure the stone is new.

On these old stones, we don't know how they were used, how they were dried/stored, how they were put away for long storage (if applicable), whether they had been put away and then used again, and then put away again... etc. I think all of that could influence the current state of the hone and how it will react, being put into regular use again.

When I think about moving stones around, having a few small boys running around the house, etc.. so operational matters, I am inclined to believe the corners of my hones are slightly (or maybe significantly) better protected against bumps, or even drops (yes, this happened).

How I seal them depends on the stone. When I hone, my stone doesn't sit in a puddle of water, so I'm not concerned about it absorbing the water from beneath. Whether I will leave a patch unsealed, or seal it completely will mainly depend on the hone itself. I have some logic I apply here, whether it is correct, or not, I don't know for certain. Let's say, a softer stone, or a thirsty stone, gets the patch. The very hard ones don't. If the bottom is solid, then maybe I'll leave it a patch no matter the hardness, like in cases when the skin is solid.

I think Christian's stone may be on the hard side, so complete coating would be OK in my mind. I understand his point of "liking the raw stone" as well. There is something about it, I can totally get it. Still, the sides and bottom corners, I would seal for physical protection. The bottom may not need it, unless there are areas of flaking, or other weak spots (this is a judgment call).

Didn't mean to derail the thread, and I hope it doesn't come across that way, because we're just chatting about this cool new rock... (:

I enjoy the chat and like seeing what other people have to say about it. I am most likely not going to seal it I don't think it will be a problem but I might change my mind later on. Since I plan on finding a midstone jnat and I will just be using this for finishing with some tomo slurry the stone should be fine.
I might do some testing to see how fast it is later but at the moment I know I can take an 8k naniwa edge and get the edge how I like in 20 or so strokes in decent amount of slurry (not a lot) then 10 or so strokes with very small slurry. There few test I want to try later like comparing edge on water only vs small slurry from tomo. Also wanting to compare edge of 8k to 10 strokes vs 100 strokes on the oozuku.
Just at the moment the 2 blades I am using to test the stone have really nice edge on it and I don't feel like messing with them haha.
Awesome stone and a lot of fun

Lots of us seal every stone. If a Alex truly feels the stone needs or would benefit from sealing he would probably mention it in the listing. Most of us do it just because it won't hurt to do it.

I would seal every stone I am going to keep. I had a very uniform defect free ohira tomae stone years ago, and I sold it to a guy who took very good care of it (I know the guy) and it separated, anyway.

I like to be able to see the layers on a new stone to make sure that the stone looks uniform through its thickness, and if not, what does it look like, but once I know that, I'd rather take away moisture variations from the sides and bottom.

I talked to Alex about it some and with what he told me I think I am just going to leave it as it. Aware of the risk but not too worried about it.

You can always do it later if you need to. My ohira stone didn't delaminate for several years. If it had been caught right away, it could've been stopped at a minor bit of cracking that wouldn't have shown up under lacquered sides. As the buyer saw it occur, though, he let it continue until it separated and he could glue it (his choice).

Many of these stones are probably 75-100 years old and haven't cracked yet, though, so as you're being advised, most probably won't. The ones that will separate along a fault, you can identify them pretty easily once you've seen a few stones. I try to buy those (price wise) expecting that they'll crack if I don't put them on a base (which seems to lower the value of a nice stone, anyway - putting a stone on a base). If someone wants to pay maruka-ish prices for a stone that's got a big fault in it, then that's easy to pass up.

Does stone hardness affect in any way the risk of splitting? Softer stones being riskier?