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Fallkniven DC4 Sharpening Stone Failure

Fallkniven DC4 Sharpener

When I sharpen my knives at home I can keep their edges in the best possible condition using a series of full-size quality bench stones (whetstones). I have a beautiful set of Japanese water stones in three different grits; course 800, medium 1200, and extra fine 6000.

It’s not feasible to carry large bench stones with me on a multi-day hike, or any hike for that matter, so whatever I decide to carry is going to be a compromise. The next best thing to quality whetstones, in my opinion, is a small double-sided pocket stone such as the Fallkniven DC4.

Fallkniven DC4 Sharpener

The DC4 has one side that has a course diamond abrasive coating (25 microns thick) and the other that is a finer ceramic made from synthetic sapphire. Inside the leather pouch I usually carry three small nails that I hammer into a flat piece of wood like a fallen tree or log, to hold the stone steady while I sharpen my knife – not my idea, but one I saw Ray Mears use.


  • Size: 1.25″ x 4″
  • Stone: 2.875oz
  • Leather sheath: 0.75oz
  • Total Weight: 3.625oz

I’ve used this combination stone with amazing results for the past year and have always carried it safely inside the leather pouch it came with. On occasion I’ve cleaned it off with soapy water as per the instructions, but probably no more than a few times.

Close up of F1 blade grind

I mention that I’ve washed the stone because recently it has developed a problem on the diamond abrasive side. If you look closely at the photograph below you will see what looks to be a blister in the thin diamond coating surface. The last time I used this stone I noticed the blister was moving as I drew the blade along the surface, so much so that I was concerned that I was going to crack open the blister and make the coating start peeling off.

Fallkniven DC4 Sharpener

Based on my experience using this stone for quite some time and from all of the exceptional reviews I’ve read from others than have used it, I’m beginning to think that this is a quality control problem. There’s no way that the few times I’ve cleaned the stone would have been enough to cause the blistering – in my opinion.

I honestly don’t remember where I purchased the stone from and it’s more than likely beyond the warrantee period anyway, so I guess I’ll just mark it down as bum luck. It’s a very popular little sharpening stone especially among bushcrafters, so it made me wonder whether anyone else has experienced the same issue with a DC4?

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Disclosure: The author purchased the Fallkniven DC4 sharpening stone with his own funds.

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  • I’ve been using a DC4 for four or five years now. I haven’t experienced the blistering. The problem I did have with it was the diamond plate becoming separated from the ceramic stone. I glued it back together with Guerilla Glue and it’s been good for the past few years. I assume that was a quality control issue as well. Perhaps Fallkniven is just lacking in that department. It’s still a great stone though. If I could only have one device for sharpening knives, the DC4 would be it.

    • Oh I agree it’s a great piece of gear and my go to stone to carry. I’m just bummed this has happened. It’s hard to see in the photos, but the ceramic section of mine is warped/twisted off to one side – how is that possible?

      It still functions for now. I figure on using it until it fails which may be years – who knows. I’ll post an update as and when the blistering finally fails. I think I may have even purchased mine based on one of your posts or comments ;) Happy new year BTW!

  • I have never used one of their stones, but I am definitely liking how compact it is. Crazy to see that blistering though. I have never encountered that before. Thanks for sharing the review and showing the photos. Looks pretty handy!

  • Guest

    It’s a lot of work but if you convex your blade edges then you can carry a lightweight strop (or just use a leather belt) in the field.

  • Rob Davis

    I usually just carry a 1″ x 3″ Arkansas pocket stone and wear a leather belt that doubles as a strop.

  • Jeff Wuslich

    Brian, which Japanese water stones are you using? Apologies if you’ve already answered this, but I couldn’t find.

    • Jeff, I don’t think I ever provide the exact details, so great question. I forget where I bought mine from, but I have a combination of three grits: course 800 ($25), medium 1200 ($35), and extra fine 6000 ($70). I know that you can get them at the Knife Center. Mine do not have a brand name on them anywhere that I can see. Hope this helps – Brian

  • zimmerman1181

    Hi Brian. I realize this is an old post, but was wondering if you had any update on the DC4. Is it still working out for you given the bubble situation, or have you found another product you like better for field sharpening, etc. etc.?

    I don’t know how I’ve gotten by without one up to this point, but I’m in need of a sharpening setup (I don’t have anything currently). Most all the knives I have are small folders (sub 4-inch blades). Would the DC4 be a good all-in-one type setup to get started on given my situation, or would you recommend something else for someone in my situation?

    I suppose, in addition to my small folders, I might want to start sharpening my kitchen knives as well. But perhaps that’s an entirely different question. :)

    • The DC4 stone is still holding out amazingly! The bubble is still there and I am constantly worried it’s going to pop and begin blistering off. As far as I can tell mine must have been a bad batch, everyone else seems to swear by them and other than this small defect it is just about perfect.

      I have a bunch of new sharpening products in testing right now, several of which would be right up your alley for folders and kitchen knives. I’ll have a review out shortly and hopefully it will provide you with some solutions or ideas. They’ll be a giveaway too so stay tuned.

      • zimmerman1181

        Awesome! I’m excited to read the upcoming review and will definitely keep an eye out for the giveaway. Thanks for the update!