Fixed abrasive stone : Recommandations for stone after DMT Coarse

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Philippe Gagnon

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May 11, 2016
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For the last few mounths I experimented with fixed abrasive stone for curiosity as I normally use waterstones (I have a lot of them).

I have been enjoying the DMT Coarse 8x3 plate as of late. I love the feel and the agressive edge it leaves. I'm looking for a finer stone to use after it. I already have a Spyderco Medium but it is now slick and doesnt cut anymore, I dont really care for it and don't want to bother with conditionning it.

I was reading about the fine or extra-fine and it seems some people compain about the quality control and the consistensy in diamond size.

Does anyone have long term experience with these plates ? Is it a real problem or does the bigger diamong go away after some use ?

I'm open to other suggestion as long as the stone doesn't slurry and has fixed abrasive.

Thanks
 
I have dmts from 120 to 8k equivalent. They all lose.some aggressiveness after a while .I don't find any of them to be badly made. Each one.improves the edge over the last plate. You can go as high as you like with them. But can save a few plates easily on the.high grit end with a pasted strop.
 
I wouldn’t hesitate to try the fine if you like the coarse (own both). Then it would be up you how much higher to take the progression.
 
I like the DMT coarse edge too. I often jump to a hard wood strop with 1 micron diamond paste after the coarse stone. It does a good job with burrs and doesn’t eliminate the bite of the coarse edge.

You could go with the fine or EF dmt stones too, but you get a different edge. More refined but less aggressive.
 
The DMT C does leave a really nice aggressive sharp edge. I think the F might be nice because it should leave some of that aggression but refine a bit more for push cuts too. I don't have the F. I have the C and the EF. The EF is a good stone for sure. I think it makes nice edges for kitchen use. But compared to the C it's almost slick. Almost. You can feel a bit of cutting and you can easily see the metal left behind on the plate. The resulting edge isn't all that aggressive, but it does have a bit of "bite" to it.

You might try following the advice of diamond paste on a strop after the DMT C. Several very learned members here have suggested that over the years (including in this thread). I have not personally tried it.

Regarding your Spyderco Medium stone: As far as I know, those stones do not wear in any way and do not shed grit. If it looks gray and shiny, it is probably loaded with metal from the blades you have sharpened. I do not think your stone needs to be "conditioned". I think it's just "dirty". So clean it. It's easy. Use some comet or bar keeper's friend and a scrub brush from your kitchen sink. It should come clean in no time. Making a paste with the powder (bar keeper's friend or other cleaner) and rubbing that on the stone first can really help.

You might be surprised by how easy it is and how well your stone performs afterward.

Good luck and good sharpening.

Brian.
 
I have quite a bit of experience with DMT's products. Our family has a hardware store with a sporting goods section, and we have been selling DMT's (and EZE Lap) diamond plates for 30 years or more. We even have one of their 6" fine (red) stones on display for public use. It has been on the counter for at least 25 years, and is still sharpening knives to this day! It is worn, but still sharpens!

I agree, the edge off of the DMT Coarse (Blue) stone is really nice. Aggressive. If you're looking for more refinement, I cannot recommend enough the next stone in their line, the Fine (Red) stone. It is 600 mesh (compared to 325 mesh for the coarse), almost double the refinement. The edge is still very aggressive, but is as refined as most knife edges really need to be, IMHO. Even in the kitchen, an edge from the 600 mesh (25 micron) stone is plenty sharp for push cuts and slicing cuts. I actually don't have the medium Spyderco (I want one), but if you don't want to purchase another stone, I would look into getting yours back into working condition. I have never had any, nor heard of any, QC issues with this stone at all. Besides the XC and C, it is the best stone in their lineup.

However, there ARE some QC issues with the 1200 mesh EF (Green) DMT plates. When new (and even after a long break in period), it feels like there are larger diamonds scattered in the EF mix. It doesn't feel right. The feedback is just horrible due to these anomalies. I just don't like that stone at all. I even sent a new one back to DMT due to this issue. They sent a replacement....same exact problem with the brand new replacement stone. And there have been many others who have commented on this as well. It's just something about that stone. The Atoma 1200 mesh is a MUCH better diamond plate than the DMT version.

I have the EEF plate as well. The 3 micron 8000 stone. I don't use it too often, only when I want to really refine edges on the more wear resistant steels like CPM M4 and ZDP189. I agree with others who have stated that they don't feel that this is a real 8000 grit/3 micron stone. It feels like a 2000 grit/8 micron stone. It is new, so it should break in as well, and get closer to its rating. The feedback on this stone is not nearly as bad as the 1200 mesh EF. I rarely use this stone, as I feel it is too much refinement for most knife cutting chores. 3 micron is where I sort of draw the line between knife sharpening and the beginning stages of straight razor edge refinement.

Bottom line, if you want to buy a new stone, the 600 mesh Fine is an excellent, excellent choice.
 
Thanks guy. I will get the D8F fine plate to try.

About the spyderco medium, I clean it regularly when I use it, it helps somewhat but I feel the stone is so different than when I got it. It feels extremely smooth and almost doesn't abrade. I remember when I got it 3 years ago, I could feel it grab the knife and I could see steel loading up on the stone after every stroke. Now it feels slick and there is absolutely no feedback when doing a stroke. I will source some 400 grit SiC and try to condition it. Will see.
 
DMT's do smooth out after a bit, but they still work fine. I used a set of fine/ultra fine DMT 6" bench hones for 20+ years and they still cut as good as new. Picked up the 8" fine/ultra fine and gave those to my BIL. I clean mine with BreakFree CLP occasionally when they load up; that works great for lifting out the swarf.
 
Philippe Gagnon said:
Thanks guy. I will get the D8F fine plate to try.

About the spyderco medium, I clean it regularly when I use it, it helps somewhat but I feel the stone is so different than when I got it. It feels extremely smooth and almost doesn't abrade. I remember when I got it 3 years ago, I could feel it grab the knife and I could see steel loading up on the stone after every stroke. Now it feels slick and there is absolutely no feedback when doing a stroke. I will source some 400 grit SiC and try to condition it. Will see.
Click to expand...

The medium Spyderco might be glazed, if much sharpening was done on steels with a lot of ultra-hard carbide content like vanadium carbides. The hone is aluminum oxide, after all, and like any other AlOx stone used on such steels, the grit might've been 'polished' by harder carbides over time. If the surface of the clean hone has taken on a glassy 'shine' when viewed at low angle toward a bright background, that could be glazing. Vanadium carbides are about 25% harder than the hone's aluminum oxide grit (First Rule of abrasive polishing = harder material polishes softer material). These hones don't shed much grit, almost none in fact, so they can't 'refresh' themselves with use and something's gotta give when they do wear. As durable as they are, they're still not impervious to wear on the surface of the hone. The linked thread below relates to the topic of glazing of Spyderco hones used on 'super steels'. It happens, and simple cleaning away of embedded swarf won't fix it. If it is glazed, hopefully the SiC grit conditioning will improve how it works.

https://www.bladeforums.com/threads/refinishing-a-white-ceramic-stone.589241/

If a lot of sharpening has been done on high-vanadium steels, then the diamond route will be much better for those anyway, down the road.
 
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Philippe Gagnon said:
About the spyderco medium, I clean it regularly when I use it, it helps somewhat but I feel the stone is so different than when I got it.
Click to expand...

Have you tried Bar Keeper's Friend? It has oxalic acid, which eats steel. It's a very mild reaction, but it's very effective in removing metal swarf that's embedded in stones. Again, making a paste with the powder and a few drops of water is nice because it keeps the chemical concentrated and you can rub and scrub it against the loaded surface to really remove that embedded metal.

I suppose it's possible that the stone needs to be surface ground using SiC powder, but I've never heard of that being the case in the 15 years or so that I've owned a Spyderco stone. I've only been active on BladeForums for about 9 years now, so maybe I've just missed the occasional report. I would encourage you to try the easy method (with BKF) first.

I'll be very interested to hear the outcome of your efforts with the Spyderco Medium stone.

Good Luck Philippe!

Brian.
 
I, too, have had good results using Barkeeper’s Friend to clean hopelessly plugged AlOx hones. Scrub with a Scotchbrite pad and don’t be shy with the elbow grease. Returns the hone surface to as-new condition.
 
Philippe Gagnon said:
Now it feels slick and there is absolutely no feedback when doing a stroke. I will source some 400 grit SiC and try to condition it. Will see.
Click to expand...

These stones are very hard and dense. I suggest you start much coarser than that on the grit, like #60. You can refine it from there if you need but I don't think you'll ever get to 400 grit, or you'll just be back to polished smooth.
 
I'm not the biggest fan of the DMT Extra fine. Typically I finish most of my edges with the DMT fine stone (600 grit). When lightly stropped, I find that the edge is very aggressive while also easily shaving. I don't care for the DMT Extra Fine.
 
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