Flattening a Shapton stone on silicium carbide?

[Mark76]

On another forum I got the question whether a Shapton stone can be flattened on a silicium carbide stone.

I don’t know, but maybe somebody here has experience. (I think a silicium carbide is a ceramic stone.)

My initial thought was that it can probably be done, although it may not be ideal. Silicium carbide is probably hard enough, but I don’t know whether pieces of the ceramic would pollute the Shapton, although I’ve never seen anything come off the WEPS ceramic stones after they are worn in. But, as I said, I have no experience in doing this.

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Mark76]

Update. Apparently we’re not talking a silicium carbide stone, but silicium carbide grains or granules. I’d never heard of the stuff. Here it’s sold:

http://www.knivesandtools.nl/nl/pt/-edge-pro-stone-leveling-kit.htm

It’s marketed as a leveling kit for the Edge Pro. (Don’t ask me why.) Does anyone have experience with it?

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Mr.Wizard]

That is normally called silicon carbide (SiC) and it is an extremely common abrasive. It’s the stuff most commonly on black wet-dry sandpaper for example. You can easily get it loose in smaller quantities at a lapidary shop. As an Edge Pro user I have followed Ben Dale’s instruction and used it for flattening stones. It has some interesting properties in this application.

• While Ben Dale recommends adding a bit of water I had no success with this; I probably used too much or too little but it just made a gooey mess so I tried it without and found that it worked just fine. I make sure the stone is dry too.
• Because the loose grit rolls around it chips away at the surface of the stone rather than (merely) cutting it down, much as illustrated in this video: http://www.youtube.com/watch?v=1hwiKscLbHA. This works very well at refreshing the aggression of coarse stones, perhaps better than anything else.
• SiC is quite friable and therefore it breaks down into finer grit as you use it. This allows you to start with very coarse grit for a coarse stone and then use the same grit for a somewhat finer stone, or perhaps several in series.
• The stuff is messy and gets into the pores of stones. (It left a gray color on a fairly porous white stone.) Given the friability of the grit this probably would not have any ill effect but it still doesn’t look clean.
• It doesn’t seem possible to get a truly dead flat surface while at the same time having the grit coarse enough to work well. For both this and the reason above I would never use this on fine grit stones when diamond plates were available. (Actually I’d use the three stone co-lap method first.)

I use loose SiC for truing and dressing stones under 220 grit. I’ll use it on a 220 stone if I want maximum aggression or if I don’t want to put wear on a diamond plate for a cheap ‘n’ nasty stone. Beyond that I’ll use a DMT X plate or finer.

[Mark76]

The stuff is messy and gets into the pores of stones. (It left a gray color on a fairly porous white stone.) Given the friability of the grit this probably would not have any ill effect but it still doesn’t look clean.

Thanks! This is what the person who asked me was afraid of. You say it wouldn’t have any effect. Are you saying it won’t have any effect on stones that are more coarse than the stuff into which the SiC breaks down? Because I can imagine that if a stone is finer, this will have an effect.

And if so, have you got any idea at which coarseness level this will occur?

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Mr.Wizard]

First off: I don’t have a microscope and I haven’t done any remotely scientific testing so this is merely speculation.

My belief is that SiC is more friable than Al₂O₃. If you try this lapping yourself you’ll see that it breaks down pretty fast. (At least the basic black kind I have. High purity green SiC might be tougher?) I speculate that even if SiC becomes embedded on the surface of an alumina stone the SiC will break down quickly and not cause any problem after its first use. Further if the pores of the stone are not significantly larger than its grit size then even if SiC works its way deeper into the stone, meaning it will persist for a while, it should not be more coarse than the original grit. I suppose the SiC could clog the alumina stone but I have not observed this.

In short unless a stone were highly porous (pores larger than grit size) I would not expect that using loose SiC would pose a risk to anything other than aesthetics. (And from what I’ve seen Shapton stones are dense.)

While writing this a memory surfaced. Shapton makes, or used to make, a flattening kit using loose grit called the Cast Iron Lapping Plate:

http://www.jendeindustries.com/products/lapping-products/shapton-lapping-products/product/126-shapton-cast-iron-lapping-plate

http://straightrazorplace.com/honing/39658-sledge-my-new-lapping-plate.html

Although I can’t say for certain I imagine that this used SiC grit. I don’t think Shapton would have sold this if it would damage their stones.

[Mark76]

Thanks!

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Mr.Wizard]

I found this series of videos through a link on Cliff Stamp’s forum. Based on these I wasn’t using enough water when I tried it with water.

[Leo Barr]

I used the Silicone Carbide on a glass plate on my Edge pro stones I used water and would begin with the 120 grit stones as you use it you can feel the silicon carbide breaking down and mixing with the ground off stones as the paste gets smother you can move up to the finer grits after use I let it dry out and then added water on the next use . I found it works well on the EP stones I have not tried it on Choseras but it does flatten the EP stones quite rapidly .

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