Thread: Choseras can crack

Not sure that this has been talked about on SRP yet.

Back a while ago, I remember one or two of JoeD's Choseras developed some cracks. I'm not sure if Joe ever figured out why or how to prevent it.

Just the other day, I was looking at my Chosera 1k, and I saw it had some cracks on it. It's just spiderweb cracks, but even those can cause major problems down the road.

I ran a google search, and found this:
Naniwa Chosera stones cracking - Knifeforums.com - Intelligent Discussion for the Knife Enthusiast - Powered by FusionBB

Some guys are talking about lacquering their hones and/or mounting them on bases. That's fine for reinforcing, but I wanted to see about preventing the cracks in the first place.

Further along, there is some talk about not letting the hones get cold, and making sure they don't dry too quickly. Both may cause cracks. I think this is exactly what happened to mine. The spot where my Chosera sits is mid 50's, and Rochester gets dry in the winter so it's probably drying out too quickly.

To try to counter this, I'm moving the Chosera to a slightly warmer spot, and wrapping it in paper damp towels after use to try to dry it more slowly. I don't think this will be so much moisture that it gets mushy.

I'm also working on lapping out the cracks that formed. I have no idea how deep they are, but this thing is VERY slow to lap. After 20 mins just now, they look a bit faded, but are still there.

So sort of a heads up for anyone with Choseras. And if anyone else knows how to prevent cracks, please do share.

I read this and immediate got up and checked mine for cracks! So far, so good. The Japanese hones were lacquered on the sides to protect the layers from delaminating, because water between the layers would lead to uneven drying. I'm not sure of a benefit to lacquering a homogenous hone.

I'm also not sure of a benefit to lapping away the cracks. As long as they aren't catching the edge, they should have no effect.

I store my greaseless compounds in a large plastic tub with a water reservoir in the bottom and a platform to separate the compounds from the water. This creates a humidity chamber for them. You could do something similar for your hones with a Tupperware (Rubbermaid, whatever) container.

I think people were talking about lacquering in case the cracks get really bad - the lacquer would provide some reinforcement. At least that's how I interpreted it.

I wanted to lap them just so they don't get any worse; I figure it's easier for a crack to spread than a new crack to form. Again, I could be totally wrong. The hone is so huge and the cracks are (I hope and assume) shallow, so I'm not worried about running through the hone.

I remember your humidity chamber idea, and I'm going to rummage around and see if I have any tubs that will work. If not, I'm going shopping. The paper towel think was mostly just a temporary solution till then.

I was just looking at a Chosera 1000 on Dieter Schmid before I read your post:
Japanese Waterstones: Naniwa Chosera

I hadn't seen this info before, but now it looks even more topical (I don't make any claims about the reliability of the information, but have no reason to doubt it either) :

IMPORTANT NOTE on storage and lubrication: Chosera sharpening stones are bound with magnesium and so have more cutting particles per unit of surface than resin-bound stones. But magnesium-bound stones are much more sensitive to prolonged exposure to water as other types of stones. So Chosera stones should NOT be left to soak in water for prolonged periods and must be stored dry. If this advice is not followed the stones can develop hairline cracks or the binding material can be leached out of the stone. It is more than enough to pour a little water on the surface or briefly dip the stones in water, they do not need to be soaked. If you are not sure that you can keep this always in mind, perhaps because you have a number of different kinds of sharpening stones, it may be better to opt for the more tolerant Super Stones.

regards,
Torolf

All the conflicting info out there really doesn't help, cause many sites that sell Choseras say they should be soaked for 15 mins prior to use. Your quote is the first I'm seeing not to soak at all and that prolonged exposure to water is bad. That also says the SS are more tolerant to water, but I thought that was the other way around (SS's get goopy faster if soaked and should never be soaked).

From the anecdotal side, in the thread I linked above the guys who store dry sometimes get cracks, but guys who store in water get mushy but no cracks. I don't want mushy, obviously, and have no intention of storing mine in water.

From my own experience, cold and drying fast definitely caused cracks. When my room was warmer and it was a bit more humid, I got no cracks. Now I'll see about cold and humid.

The unbacked ones can crack indeed, but from discussions I have seen that would happen after the stone is pretty thinned from use.
I have not seen any signs of it on my 600 grit one, but I have been thinking of backing it for some time now.
The ones with bases should be fine, I have had my 1k one for more than a year and is not showing signs of damage at all.

Oh, I guess I should have mentioned that mine only has cracks forming on the one side I use to hone and the areas where water drips down the sides while I'm honing. I'm guessing this is because those are the only areas where water has really soaked in, so they are the only areas affected by the rapid drying.

A thought that is commonly used in woodturning to slow the drying of wood to limit the cracks, is cheap and most people already own: paper bag. Place your stone in a thick paper bag and the moisture is slowly released through the paper. If you want you could try to double the bag. You could also try spraying inside the bag to create a small environment with a higher humidity than you live in.

On another note Glen soaks his Naniwa SS in a sink of water in his new honing videos and said it helps the stone settle in so it works better...

I haven't tried this yet but maybe Glen can Chime in about how it's said that the SS will turn gloppy if soaked....

Are you sure they are 'cracks'?

My Chosera #5000 I have had the longest and has a patterning all over the surface. I have always thought this to be water stains and never given it a second thought. Did your finger nail get caught when feeling for it? I have soaked my hones in the past but never for more than 40 minutes, as it states (in Japanese) on the side of the hone, but recently have just misted the tops until nothing more sinks in. This was because my whole set (with stands) won't fit in the honing tub I used to use.

The misting has worked fine for the last month or so. So I don't think I will be soaking them any more. Just the misting.


FYI: I have the #1000, #2000, #3000, and #5000 Chosera. My #10000 is a Gokumyo from Suehiro.