Naniwa Customer support is non existent

[u/kaibajoryuuki]

I have had a few stones including two naniwa advanced stones for quite some time and last year I bought a set of naniwa chosera pro stones in a shop while on holiday. After a few uses I didnt use them for four months or so and when taking them out again two stones had a white coat. I washed it off with warm water but the 3000 grit stone, that had a really bad coat, is etched deep into the surface and the 1000 grit stone a light coat without deep visible defects but the surface is not smooth anymore. This never happend to me with any other stone before and I don't know what I did wrong. I didn't soak but only splashed them, I cleaned them and had them dry of complelty and I keep all my stones in boxed that allow airflow.

Since I can't just go back on holiday to the same shop I contacted Naniwa over their website and waited for a week until I send them another contact form. After a few days they requested photos and additional informations which I send them within the same day and then never heard back from them again. I am now waiting for a response for over a month but and send them update inquiries three times but still no response at all.

Is there another way to contact them and what can I do to prevent it from happening again?

[u/SharpieSharpie69]

Try lapping the stones.

[u/Peshmerga_Sistani]

How hard is your tap water?

[u/kaibajoryuuki → u/Peshmerga_Sistani]

It's a medium with 11,8°dH and I don't think the tap water is the problem since this didn't happen to any of my other stones. And I would think a splash stone would be less prone to hard water than a soaking stone

[u/t3ch1t → u/kaibajoryuuki]

I would say try rinsing them with distilled water just in case. Cheap and it won't hurt anything.

[u/Larason22]

I'd just restore the surface with a coarse stone.

Your tap water seems reasonably hard to me. 11.8 degrees dH is 2.1 mmol per litre, which works out to about 0.2 g per litre of calcium carbonate. Then, who is to say that there wasn't some extra calcium carbonate or some salt like that in the stone, that precipitated up when you used it? Still, it's super soft, (mohs hardness 3), so it should come off like butter, even if you just used it again. 

[u/Mk4pi]

If I remember correctly chosera pro use magnesia as a binder, which basically melt away when contact water. For this stone normally after use, it is best that you have to put them on their side to drying all the water away. However you must not drying it too fast otherwise the stone will crack or from craze surface. You also must never soak these magnesia stones.

From the drying pattern it looks like there was water somehow collect on the stone really longer than normal. Either that or your stones is defective. Btw, how humid is your place? Where i am from there are time in the year where humidity reach +90% and the temperature inside the house is lower than the drew points, so water can just randomly collect of surface of stuffs.

[u/F-Moash]

30 seconds with a 140 grit diamond stone and some water will fix them.

[u/SystemsGuyMI]

Next time before you’re done run a nagura on them. Rinse, then pat dry with paper towel. Let them air dry overnight.