DMT WTF

So I'm lapping my Chinese 12k with a brand new D8X in the sink under a constant stream of water, and after a few minutes of going at it I pull them apart and look what happened! It looks like there is a raised diamond or something that is roughly abrading one spot. The rest of the surface? Nice and smooth. I even "broke in" the DMT beforehand by running a screwdriver over it a whole bunch of times. And I checked the surface of the DMT, it wasn't damaged at all, the look and feel of it are still there.
So what happened? Still need to be broken in?

On top of this, I've only had it for 2 days and I can see rust developing on it! Rust! On the honing surface, and sides! I even dried it with a towel after I was done with it! I didn't use a hairdryer or anything, but there weren't any water beads when I put it on the table to dry.

I contacted the online retailer (a very reputable one, won't name it publicly) about the scratches it was putting on my stone and was told that, "this happens from time to time" and to just "use it till it goes away." As to the rust, I was told that this is only a cosmetic issue and won't affect its use.

Please someone tell me this is normal!!!
As you can probably tell, I'm pretty p*ssed off right now. :cen

The rust is normal.

Try finishing it with a d8c. In fact, I'm not even entirely sure those scratches even affect your hone. I could be wrong, but I'm not sure the hone is all the worse for it.

Honestly, yes it is normal. "Use it till it goes away" is correct and both of mine initially rusted a little and then never did it any more. I don't know why the rust stopped. Regarding the scratches, yes it must be due to a couple of raised diamonds on one end. You can either try to break it in more or just live with it. The scratches in the hone will not affect the function of the hone, just its cosmetics.

I'm sure you're not happy with it now and maybe your vendor did not try hard enough to convince you, but your DMT will be fine soon!

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Originally Posted by Leighton

Try finishing it with a d8c. I actually wouldn't have used the d8x on a chinese 12k. D8X and XX would be reserved for the most stubborn of ceramics.

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Actually, I'm not sure what a D8X is. The D8C is 325 grit and the D8XX is 120 grit. I haven't heard of the D8X. I do disagree about restricting the D8XX from the Chinese hone. Personally I think the D8XX is the only appropriate diamond plate for lapping hone.

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Originally Posted by Utopian

Actually, I'm not sure what a D8X is. The D8C is 325 grit and the D8XX is 120 grit. I haven't heard of the D8X. I do disagree about restricting the D8XX from the Chinese hone. Personally I think the D8XX is the only appropriate diamond plate for lapping hone.

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D8X is 220 grit or thereabouts. Your right, the D8XX is probably the only true lapping stone among the diasharps. However, DMT recommends the Duosharp line for lapping waterstones. :shrug:

+1 on rust. hasn't gotten worse.

I used a D8E 1200 for my lapping after lots of recommendations here. SLOW!

I tried lapping a spyderco UF on a d8e to get a more polished finish on the stone and I got some brownish slurry after a few circles. I stopped immediately. Do not recommend using the d8e at all for lapping anything after that experience.

Thanks guys. It is good to know that the rust is normal. Frankly, I was shocked when I saw it.

And I went back and ran a screwdriver over it about 200 times. It scratches a lot less now. I'll do some more in the morning, hopefully I can get that one rough spot out.

Hold on. The diamonds are embedded in nickel. Does nickel rust (at least that quickly)???:confused:

Are you sure the surface rust isn't swarf from stuff you used to break it in? A scourer and powdered cleaner might get rid of it.

Yeah, those gouges will fade with time, I even did the same "break in" type routine as you and had the same results. I fixed that by quick-lapping a spyderco hone;).

As far as the rust goes, I had the same problem and it stopped as well.

To minimize development of further rust, I also let my DMT dry resting on edge after I run it under hot water and scrub it a bit, so there's no chance of pooling and the water evaporates faster.

I had rust develop rather quickly on my D8E as well and then stop just as quickly. It is a very faint orange stain looking thing, only on a portion of the hone. My D8C still looks great, though.

DMT sent me a cleaning kit when I returned a defective plate. They sent it along with the replacement. Their customer service is first rate. I also had the rust and it isn't an issue. The cleaning kit includes something like Comet or something similar and a scrub brush with brass bristles. Every now and then it is good to give it a good going over with the brush and some cleanser. Here is a grit chart for DMT.

+1 on the rust not being a problem.
And if it is a raised diamond, try breaking it in with the back of an old chisel or so until the raised diamond is gone. Try to find out where exactly it is. You may have missed it when you used that screwdriver.

The only thing that managed to break in my D8C was
(attempting) to lap a Spyderco ceramic hone.

- Scott

I don't recall having the scratching problem you have, but I did have the rust problem. The end of my extra course was a little bit raised and the stones I was lapping eventually lapped the dmt flat and removed the diamonds from the end. That exposed the surface underneath the nickel and diamonds. I think that's why mine rusted. I have a rubber holder I use from time to time and if I don't take it out so it can fully dry, it will develop rust where the water was trapped between the hone and the rubber.

I must wonder at what exactly "prepping" the DMT actually does. If we're removing diamonds through that process, it doesn't sound too good IMO. However, I can't think of any other plausible explanation. Maybe pushing the diamonds down into the nickel substrate? I find that unlikely as well. We can't wear down the diamonds because nothing is harder than a diamond. Thus, the removal of "offensive" diamonds is the only theory that makes logical sense. Anyone have thoughts or findings?

Well, diamonds are hard, but they fracture. I think the initial break in fractures off the high points.

Diamonds are super-duper hard, but even they wear down over time. They aren't adamantium after all. ;)

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Originally Posted by joke1176

Well, diamonds are hard, but they fracture. I think the initial break in fractures off the high points.

Diamonds are super-duper hard, but even they wear down over time. They aren't adamantium after all. ;)

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That makes sense.:nj

The diamonds that are going to get worn/fractured first are the few that are projecting higher than the rest as they are going to get the brunt of the force either from the tool you are using to break it in or from a hone. After it gets down to the level of the rest of the diamonds, the force on the diamonds is uniformly distributed and then you get scratch-free lapping.

Did you send them the pic you posted here? That can't be "normal". It might not make much difference/damage to the hone you're lapping but I can't imagine that being good if you honed something on that DMT...

Ok, so results from one week later.
I have gone over the DMT with all kinds of metal. Screwdrivers, wrenches, pliers, bicycle handlebars. I have worked on this over the course of five days, each day running some piece of metal back and forth, in circles, slowly then quickly, all over the edges and surface of the DMT. Then I go back to the Ch12k, and lap the crap out of it under running water. Cumulatively, I have spent hours and hours on all this. The scratches have reduced in severity, but they are still there! Is this the best I can hope for? I know that the D8X will leave a scratch pattern on fine hones. I'm fine with that. But is it too much to ask for a uniform scratch pattern, and not just one rough spot on the DMT that scratches the hell out of my hones?

Call up DMT and send it back. I hear they have great customer service. I'm waiting on them to get back to me.

OK, you have followed DMT's advice to the letter and it hasn't broken it in adequately. Under the circumstances you would be justified in saying the plate is defective and asking for your money back or a replacement.

The trouble with a replacement is you will have to break it in again. :gaah:

You have to make a tough decision. Make do with it as it is, send it back, or do something drastic to break it in.

I think to get rid of that high spot you would have to use something big and flat like the back of a plane iron (blade.)

As a last resort lap a waterstone like a Norton 4/8K and let the slurry build up. Have the diamond plate on top. I don't care if it's a D8X, enough slurry will start stripping away that surface and break it in real quick.

This is exactly what I experienced with my D8C, and I
didn't get much help from the vendor. I should've just
sent it to DMT themselves, but I just lapped a few
ceramic hones (Spydercos) and it was fine after that.

- Scott

Hey Hunter,

don't worry about the scratches, they will go away. Same thing happened to my 12k and honestly it performed better than before. When you bring me the loner stuff bring it so I can take a look a it. By the way my scrathces are barely noticeable now.

Raf