Scratch marks in stones after lapping

I'm getting ready to start keeping my razors in shape, and I've got a Naniwa SS 5K, 8K, and 12K. I also got a DMT 325 plate to lap them. I got them through SRD. So, I thought I would lap each stone as that seemed to be a pretty standard recommendation, and I figured it would have to be done at some point anyway.

After lapping them with running water and using a figure 8 type of pattern, I am noticing that there are scratch marks on the tops, and the tops of the stones where I've lapped them do not feel as smooth as the bottom of the stone that I haven't lapped. Please, please, please tell me that I've not just ruined the entire set up.

I think 325 is good for removing a lot of material quickly. I usually go up to 1200 lapping. That leaves a non scratch surface. However lately, my worn coarse DMT 325 has been leaving a polished finish. Maybe yours is not broken in yet...

Your stones are not ruined, take a screwdriver or a heavy cleaver and use it to knock down the high diamonds on your dmt, they need to be nicely worn down first, after a while they will. Leave a grist fins on your stones.
Plus the low spots from a high diamond won't affect your edge only high spots, not to mention you still have the other side too. So your fine. Tc

Everything is new, so I would assume that my DMT 325 is not broken in yet. What do I do in the meantime? I am guessing that I should not try honing on the stones if they don't have a non-scratched, polished finish.

I thought that I would be good to go right away running the DMT over the stones a bit.

Just do as TC recommended and knock the high diamonds down. It does not take a lot of effort or time to do. Then relap your hones.

Bob

That happened to me the first time I used my DMT325 and I thought OMG I ruined my homes. It is common enough with DMT325s that there are a few threads on it here.

Or, you could go outside and hone the sidewalk for a few seconds at a time. Even a red brick....
:rofl2:
Seriously!

I agree with the above comments. A coarse DMT would leave some scratches and needs to be broken in. Just sharpen up all you kitchen knives and anything else you can fine. ahaha.

As for lapping in the meantime and with finer grits, for many years I used a 12-12" granite floor tile from the hardware store and some wet dry sandpaper. tape it down and have at it! Works great. Just be sure to clean the hones very well to avoid grit contamination. Now I use DMTs 250 to 1200. But I wouldn't hesitate to use the tile method again. Saves having to wait to break in the DMT and saves you buying more DMTs for a while if you don't want to.

Furthermore, Scratches wont hurt as long as they don't "catch" the edge, as said above

Imagine a bed of nails. You can lie down on it because the nails are all of the same height and so the pressure is uniformly distributed. Now imagine the different effect if one nail stuck up a half inch higher. That nail would hurt.

The advice above is right because of a similar problem caused by high diamonds. If all the diamonds were the same height, they would cut uniformly and leave a smooth surface. If a few diamonds are higher, they are going to cut into the hone deeper and will leave scratches.

To summarize: take an old screwdriver, socket extension, or any other straight piece of steel, spray some water on your DMT, and rub the steel back and forth over the surface for a bit - refreshing the water as needed. This will break in your DMT, you will be able to feel the difference as you do this. When done wash all the swarf (steel and diamond bits) from the DMT and relap your hones.


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Feeling much better! Thanks all!

Sometimes a high diamond will resist the above methods of breaking in a new DMT.

If you are still getting scratches carefully do one lap at a time to locate the high diamond. Then go after that spot with a screwdriver. You may have to test in two directions at 90 degrees to precisely locate it.

Or sharpen a couple kitchen knives on them, you will feel where the high spots are.

Also, start by beveling the edges of the stone, that will knock down the high spots.

I just had same issue two days ago with my new dmt and shaptons. I even honed a couple knives before using it to lap my hones. It still left scratches in my hones which didn't affect honing at all. You're gonna be fine, no worries :)

Yup. I call those scratches negative honing surfaces. They don't hurt anything and over time your diamond plate will sort itself out.

Agreed. It's only cosmetic. No sense in scraping more of the hone material off. Definitely season the DMT before using it again.

I remember when I bought my dmt with Shapton glass stones.

A high patch destroyed my honing surface, I couldn't figure out why my 30 k felt so rough when honing.
Years later and much effort my dmt is worn and even.

As long as it is not one area with a high patch you will be ok.
The scratches shouldn't effect the honing.

Try the screw driver shank method ..

Even a decently worn 1200 plate will leave some scratches, it is 1200 after all, though as Ron says the scratches are not harmful. Those scratches though, always seemed to be 'not in harmony' with the idea of a high end jnat so now I lap using sandpaper on plate glass up to 2000 grit on the finest finishers. Here's a couple of tips to try.

If you're using synths, try the King 8000 grit slurry stone to clean hones after use and smooth the surface after lapping. This stone I believe, was designed to create slurry, and it does, but I can tell the surface is much smoother than after using the Naniwa brown biscuit.

On a jnat finisher, nearly all the wear comes from raising the slurry with a tomo, not honing the razor. Use the tomo with even pressure over the entire hone surface and you'll almost never have to lap the stone.

Cheers, Steve

Quote:

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Originally Posted by Steve56

Even a decently worn 1200 plate will leave some scratches, it is 1200 after all, though as Ron says the scratches are not harmful. Those scratches though, always seemed to be 'not in harmony' with the idea of a high end jnat so now I lap using sandpaper on plate glass up to 2000 grit on the finest finishers. Here's a couple of tips to try.

If you're using synths, try the King 8000 grit slurry stone to clean hones after use and smooth the surface after lapping. This stone I believe, was designed to create slurry, and it does, but I can tell the surface is much smoother than after using the Naniwa brown biscuit.

On a jnat finisher, nearly all the wear comes from raising the slurry with a tomo, not honing the razor. Use the tomo with even pressure over the entire hone surface and you'll almost never have to lap the stone.

Cheers, Steve

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Replace Jnat and insert any finishing stone, synthetics included, and I'm of the same mindset. The scratches may not be detrimental, but they still kick up my OCD. I still use the DMT or a diamond plate when I need to flatten, but after the stone is flat like I want it's time to switch to sand paper and get the scratches out. Well, depending on the stone.

My low grit 800 and 1K stones only get hit with the DMT. Middle grit and higher get 1-2K at least. My naturals are all high polished.

The naniwa biscuit is pretty coarse, but I'm coming to like it. Seems to clean things up nicely and doesn't leave scratches that are too terribly deep. It makes sense the King slurry stone would be finer though. I think I read somewhere the Naniwa biscuit is something like 400 grit? The surface I've been using doesn't feel that coarse, but it sure does clean my synthetics off quick. I might have to put one of those King stones on the wishlist somewhere, I like the sound of it.

Another option is to use a small piece of cheap hard Arkansas hone for creating slurry. They are common for knives and often only cost a few bucks. Their advantage is that they are so hard that all of the slurry will come from the synthetic and itwill leave no scratches at all.

Quote:

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Originally Posted by Steve56

Even a decently worn 1200 plate will leave some scratches, it is 1200 after all, though as Ron says the scratches are not harmful. Those scratches though, always seemed to be 'not in harmony' with the idea of a high end jnat so now I lap using sandpaper on plate glass up to 2000 grit on the finest finishers. Here's a couple of tips to try.

If you're using synths, try the King 8000 grit slurry stone to clean hones after use and smooth the surface after lapping. This stone I believe, was designed to create slurry, and it does, but I can tell the surface is much smoother than after using the Naniwa brown biscuit.

On a jnat finisher, nearly all the wear comes from raising the slurry with a tomo, not honing the razor. Use the tomo with even pressure over the entire hone surface and you'll almost never have to lap the stone.

Cheers, Steve

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I never thought of using high grit sandpaper on my jnats.
Normally I use my Shapton lapping plate and then I do some 1200 Atoma, finally I break a sweat using a soft nagura.
What I find shocking is how easily it is to dish out (probably a fine shallow dish)my Nakayama which is hard and I do slurry from the edges.
In saying that though, I do a lot of honing on that stone.
I will try the sandpaper method next time, hopefully no bits will lodge in the stone.
Cheers..

When I started out in the honing game I used SiC wet & dry paper (in wet mode, i.e. with water but some folks use WD40) on a flat tile to flatten my hones. I used my 325 DMT to sharpen plane irons and wood chisels before I ever applied it to a hone. By then it was just right to bring hones to a smooth flat surface - or to generate slurry for faster cutting.