Problem: Stones useless after flattening....

[jangul]

Can anyone help me to understand what has happend here?

Flattened my shapton (ceramic) 120 and 220 with a 400 diamond plate. After flattening they lost all effect. The knives just slides over, no feedback and no steel comes off....

Any ideas how to fix them?

[ken123]

You need to flatten with something coarser or after flattening, retexturize the surface with a rougher stone or plate. You are cutting THROUGH the particles on tje surface. At least use a 140 grit eg Atoma or for even more aggression use a 24 grit Nubatama or 60 grit diamond plate. I carry these.

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Ken

[Lepus]

Like Ken said the plate's abrasive is cutting your stone's abrasive. You need to at the very least remove the top layer of now duller abrasive. A coarse plate certainly will do this, but you could try to free up abrasive with another more tightly bound stone and some friction. Once you get deeper into the stone and free up some abrasive you will see your results improve again.

Usually if I manage to "dull" a stone I let myself work the abrasive off with a knife. That could be a problem with the Pros since they don't dish very quickly, but my 220 actually sheds abrasive fairly readily and apparently the 120 is even softer and looser. The converse of flattening a finer stone with a very coarse plate is also somewhat true; if you flatten say a Shapton Pro 8000 with an Atoma 140 it will seem particularly aggressive for a while until you've worled dowm those deep, deep diamond scratches.

I don't have a 120, but if I did I would consider lapping it and my 220 together instead of lapping them on a plate. I have a few chunks of a 60 grit stone I used for a whole to texturize coarse stones when necessary, but since I shifted to using an Atoma 140 more often for knives that has been less useful.

[Thuja Magus]

Get some silicon carbide powder something like 60 grit works great and rub the 120 on the 220 with the powder.

[gladius]

Get some silicon carbide powder something like 60 grit works great and rub the 120 on the 220 with the powder.

—-
+1

...I was just typing that EXACT recommendation!

Didn’t Mark just get some in recently?

I use the 80 grit powder and it is fast and cheap.

[jangul]

Thanks. Really love this forum.

I forgot to mention that I've tried to rub the 120 and 220 against each other, but it didnt have any effect. Perhaps both was now to smooth, and about the same hardness.
I'll order some powder, and try.

Or would you recommend the Atoma? They are quite expensive here in Norway, about 150 usd (and about the same from CKT, with single shipping and taxes). Could use one for thinning my Fallkniven knives, if its durable. My other diamond plates seems to loose the abrasive fast...

[Jason B.]

The Atoma 140 will kinda work on the 220 but makes the 120 very smooth and not cut well at all. The SiC powder is the best option because it actually exposes whole fresh abrasive and gives the stone better surface texture which is very important with ALL Shapton Glass stones.

[ken123]

I now have 46 and 60 gtit diamond plates. These are game changers for coarse grit stone flattening. Less than Atomas and I ship internationally.

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Ken

[Lepus]

Less than Atomas you say...

What differentiates one from the other? I would expect the 46 grit to usually just be the better choice.

[ken123]

Less than Atomas you say...

What differentiates one from the other? I would expect the 46 grit to usually just be the better choice.

A full size (8x3) plate is $60. The 46 is slightly rougher thsn the 60.

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Ken

[Jason B.]

I have a diamond dressing tool (about 60 grit)that I have used on my SG120 to get it cutting better. It did ok but was really aggressive on the surface and didn't leave a very good texture. IMO, very Coarse diamond plates are not very good at texturing and one should follow the recommendation of Shapton and use SiC powder for the best result.

[journeymandoug]

I find that conditioning the surface is best left to steel being sharpened. Flattening, is always handled by my extra course plates. Make sure you rinse and even scrub the surface of your stones pretty often. Once loaded, which requires fewer particles than you’d think, especially on finer stones you are basically scrubbing your steel across a surface composed of the exact same steel. I use an edge pro to set bevels, so the smaller stones need a little more care. Shaptons are easy to load, because they require so little water.