Norton Medium Crystolon stone seems worn smooth, cuts slowly

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bgentry

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Aug 3, 2009
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I have kind of an unusual Norton combination stone. It's an 8x2x1 with Medium Crystolon on one side and Fine India on the other. As far as I know, they stopped making this quite a few years ago.

I've used mine a decent amount, but I haven't really done much with it in the past 5 to 7 years. So today I did an experiment with it, and tried to resharpen my Yojimbo 2 in S30V after dulling it by cutting into the stone several times and making a pretty darned wide flat on the edge.

It did not go well. I essentially gave up after about 35 minutes, as I was fatigued and didn't want to continue. I noticed that the blade seemed to "skate" on the stone quite a bit and only seemed to really "bite" when it touched the corner of the stone as I got near the heel of the blade.

The side of the stone feels more coarse to my fingernail than the surface, but it's hard to be precise with a fingernail scratch test. I've always used this stone dry or with water. Today it was with water and quite a bit of it. Part way through sharpening I tried to "refresh" the surface a little with about a minute of scrubbing the stone surface with a tile rubbing stone. It definitely produced some grit, which I'm confident came from the Crystolon stone. But it didn't seem to rough up. It still seems "slick".

I'm not sure how much of this is wrong expectations (from a "medium stone") and how much is a clogged/smoothed/worn stone.

Any suggestions?

Brian.
 
My suggestion: don't use a sharpening stone to intentionally dull a Yohimbo 2 or other fine knife! :)
 
Barring some kind of problem with the stone, I'm going to say it's a clogging issue due to lack of oil.

Try this.
Clean the stone with oil only, no soap, no water.
Use the stone slightly wet with oil, this will help dislodge the contamination.
Clean with oil again and repeat.
In time the stone should be cutting good again, even to the point you can use it dry (after being oiled).

I know a lot of people do it, but suggest not using this type of stone with water or soap, as I've found it only degrades performance.

My heavily used jb8 (SiC both sides) is much smoother on the sides than the working surfaces.
 
Is the stone, or one side of it, actually labelled as a 'Crystolon'? I ask this only because that 'slick' or 'skating' behavior sounds more like a glazed aluminum oxide stone. A tile rubbing stone or any similar aluminum oxide stone should easily remove a LOT of grit from a SiC stone, if the ones I have are any indication. So far as I know, Norton's Crystolon and any other SiC stones I've seen should shed grit with use (therefore refresh, purported to be an advantage of SiC stones), which also suggests your stone may not actually be SiC, if it's not refreshing as such. I've used a tile rubbing stone to flatten and chamfer the edges of some of my SiC stones, and the method works very quickly. Also, even something as simple as cutting into the stone's surface with a knife's edge can also quickly groove the surface of a SiC stone, at least enough to see it. Might look for that also.


David
 
Obsessed with Edges said:
Is the stone, or one side of it, actually labelled as a 'Crystolon'?
Click to expand...

The side of the stone says "IC8", which I believe indicates India and Crystolon. I have original box somewhere and I'm very sure of what it is because it's no longer available and so unusual compared to what most people have.

I've used a tile rubbing stone to flatten and chamfer the edges of some of my SiC stones, and the method works very quickly.
Click to expand...

I've rounded over one of the long edges of the Crystolon side using that same tile rubbing stone. It knocked off the corner rather quickly and allowed me to form a narrow radius on the corner with a few minutes of effort.

When I used the tile rubbing stone on the surface of the Crystolon, I didn't spent much time or apply very much force. I know from experience that I'm not very good at flattening a larger stone with a smaller stone and I didn't want to "unflatten" the Crystolon stone. I was hoping to just rub off some of the top layer.

Thinking back, I'm pretty sure that this behavior of the stone seeming too smooth started a long time ago and is part of what led me to trying other stones. I may have a bad stone, or maybe just one that needs to be conditioned. It was brand new when I purchased it and has been used for a reprofile job or two, but hasn't been used nearly as much as my other stones.

Brian.
 
bgentry said:
The side of the stone says "IC8", which I believe indicates India and Crystolon. I have original box somewhere and I'm very sure of what it is because it's no longer available and so unusual compared to what most people have.



I've rounded over one of the long edges of the Crystolon side using that same tile rubbing stone. It knocked off the corner rather quickly and allowed me to form a narrow radius on the corner with a few minutes of effort.

When I used the tile rubbing stone on the surface of the Crystolon, I didn't spent much time or apply very much force. I know from experience that I'm not very good at flattening a larger stone with a smaller stone and I didn't want to "unflatten" the Crystolon stone. I was hoping to just rub off some of the top layer.

Thinking back, I'm pretty sure that this behavior of the stone seeming too smooth started a long time ago and is part of what led me to trying other stones. I may have a bad stone, or maybe just one that needs to be conditioned. It was brand new when I purchased it and has been used for a reprofile job or two, but hasn't been used nearly as much as my other stones.

Brian.
Click to expand...

Looking at one of Norton's online catalogs seems to indicate they do have an IC6 and IC11 (combo India/Crystolon stones in 6" & 11" lengths), so I'd assume yours should be Crystolon on one side.

Has the stone ever been used to lap other stones (natural/AlOx stones)? If so, I might see a possibility of another stone's grit clogging the surface of it; just a thought. I'd think it'd take a ton of steel swarf from sharpening knives to clog it so bad as to create that 'skating' behavior.


David
 
It sounds like its glazed and needs to be lapped with loose grit and soapy water or oil. On my oil stones that need it, I use soapy water and some 120-220 grit loose SiC on the fine side and 60 grit on the coarse side. Blasting grit or even sand might work as well.

Are you using it with oil?

The only time I have any issues with mine are if I've lapped it flat with a diamond lapping plate. I've done this twice since getting this stone years ago, it needs a lapping with loose grit to totally restore the surface. After that, I just use it with oil and it stays like new.

Edit to add:
I re-read the OP and noted you use with oil or dry.
When using with water or dry, it will over time lose a step and glaze up. Lapping with lose grit will work wonders, and after that oil is best for regular use.
 
Perhaps I'll have to figure out how to lap it then. I don't have anything large and flat to use. I'm not willing to risk my DMT plates for this stone due to cost. Maybe I can find a tile to use. Maybe some fill dirt sand for "loose abrasive"?

Or maybe it just goes back in the box again. I really pulled it out to play with because I wanted to have some real world data about how fast or not fast crystolon stones cut.

I'm tempted, in various threads about sharpening setups, to recommend a stone progression that starts with the Coarse Crystolon, but I don't want to do that without at least *some* recent experience with the Crystolon stones. Maybe that will have to wait. <shrug>

Brian.
 
A flat piece of sidewalk, backside of a ceramic tile, soapy water and some sand. You aren't really grinding down the surface anymore, just getting it to release that spent abrasive. You can even just load it up with oil and grind away on it with an old file, piece of hacksaw, anything to get it to refresh itself.

I remember seeing a listing for that combination stone, then went back to get it and couldn't find it. It sounds like a near perfect combo for general sharpening.

Keeping the surface in good shape might be secret #9 or 10...
 
You can still find the 11 1/2" x 2 1/2" x 1" version of that stone, the IC11.

Sidewalk + soapy water + sand = poor man's flattening plate. I've done that with my economy SiC stones and it seems to work. I had partially glazed the surfaces on a couple of them by trying to lap them against each other dry. It did flatten them both, but at the expense of the ability of either to cut steel very well afterwards. Luckily it was a couple of sub-$10 stones. Good learning experience, though.
 
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