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Diagnosis needed

Mon Jul 07, 2014 8:30 am


I just bought a Shapton 8000 glass stone from you along with the Shapton 6pc Starter Set Glass Stone Starter Set. The 8000 seems to load up very quickly even when it has plenty of water on it. The other two stones seem to float most of the metal off but the 8000 just wants to hold it in making it hard to use. Is there anything I can do to prevent this? Should I be using a Nagura stone on it?

Is the Kitayama 8000 or any of your other 8000 grit stone work better without loading? I just want a really good 8000 stone so need some advice on which one works best without the loading problem I am having with the Shapton 8000.


Re: Diagnosis needed

Mon Jul 07, 2014 8:37 am

Hi Larry,

High grit stones load more quickly in general because the grit particles are very tightly packed together and as the metal cuts the steel, the steel particles plug up the stone and the knife skates across the stone. Most high grit stones are also tend to wear slowly and don't usually require a lot of soaking either. All these characteristics are common with polishers over 8K.

I don't recommend you buy another stone yet, but work with the one you have. The shapton glass is is a good stone and I would recommend you try flattening the stone before each sharpening session. You can also use a flattening plate to quickly clean the stone if you're sharpening a bunch of knives at the same time. This should remove any residual particles that is making the stone load and see if that helps. Many people want to "conserve" their stones by not flattening enough. Try it and then come back and report.

Re: Diagnosis needed

Mon Jul 07, 2014 9:41 am

using just a little bit of CBN spray or emulsion on the stone will help to float the metal and the stone won't load up. just make sure the spray or emulsion is water based. all of Ken's sprays and emulsions are water based, but not the pastes. the pastes are oil based and will damage the stone. i'm not sure of other manufacturers products.


Re: Diagnosis needed

Mon Jul 07, 2014 2:22 pm

Or use a synthetic nagura every so often to clean the swarf out of the stone. Only good use for one of those IMHO.

Re: Diagnosis needed

Mon Jul 07, 2014 4:33 pm

Adam Marr wrote:Or use a synthetic nagura every so often to clean the swarf out of the stone. Only good use for one of those IMHO.


I just tend to use my fingers and a little bit of water to flush the surface and keep on polishing. Even though the stone loads it will still cut. Sharpen until you get a fair amount of black swarf and dark stone surface, then flush with clean water and maybe a nagura, then finish with lighter pressure.

I tend to lap my stones shortly before each session and just allow the normal amount of loading occur during sharpening.

Most polishing stones will load to a degree, but they do still keep polishing. It takes a good bit of swarf and dry conditions to make them stop cutting, so remember to keep them wet.

If you don't have lapping plates or a nagura you can just use another sharpening stone of coarser grit to freshen the surface. I imagine a little square of sandpaper could achieve this as well; either way be sure to get all the coarser grit off of your polishing stone when you are done. (to avoid grit contamination)

Re: Diagnosis needed

Mon Jul 07, 2014 10:01 pm

There's lots of interesting 8k stones, but you should master the one you have first. It will make your next stone more fun.

CBN and boron carbide will certainly pretty much eliminate the metal swarf problem. Just a drop, preferably 2 micron size added to the slurry will do it - and improve the stone's function too. It abrades the stone surface more rapidly improving cutting action, slurry density AND also adding an abrasive capable of handling harder steels more efficiently. This keeps the metal swarf from accumulating. A small piece of 8k stone - eg glassstone or pro can abrade the metal swarf off too. Lapping the stone with a fine lapping plate - 600 grit will do the trick nicely and keep the stone flat as well.

I'm even less charitable than Adam regarding synthetic naguras. Pretty much have no use for them. They are usually just inferior sharpening stones

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