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Lapping an Arkansas in excruciating detail

Inspired by this thread, I thought I'd post up how I flatten and dress a stone.

I'm dressing a hard black Ark with unknown branding, a $20 used tool store find that was finished very rough, maybe 36 grit on all surfaces when purchased. I was hoping I might luck into something like Keith Johnson's favorite, opaque black ark. This one is totally opaque, with some lighter figuring/veins much like the one he's fond of. I doubt this one is equal, but the search is always the fun part.

Anyway, here goes, and you can see how things change slowly along the way.

I've been working with a couple baggies of SiC powder I got from a kind knife forum guy. Recently invested in a full set, and it's definitely made things easier. You only need 1/4 - 1/2 tsp. of each grit for a stone this size.

I like to use a dead-nutz flat marble counter offcut, with sacrificial high quality sandpaper to save the marble surface from dishing (Cubitron or Precision Pro Grade for coarse grits, Rhynowet for finer grits). These papers are incredibly durable, and I can lap many stones on a single sheet. I wet the back and front of the paper with Windex or some cleaner to make it adhere to the stone, prevent slipping, and lubricate the SiC powder.

What does the cutting speed depend on?
  1. Sharp abrasive
  2. Pressure (the fraction of force divided by area, in a literal sense)
  3. Distance travelled over the abrasive
How does this affect the process
  1. Refresh your abrasive every so often, and clean off the old. You don't need much, but you want good contact between the stone and the loose grit. If you let a bunch of worn grit accumulate on the paper, fresh abrasive dulls itself on old abrasive. If you only use fresh, it'll cut faster. I don't have a recipe for how often - be observant.
  2. More pressure cuts faster, but too much can be destructive to the paper and the stone. Just be aware of how you angle the stone. Even 800 grit powder will round a sharp corner really quickly because of the small surface area. Work on keeping the stone flat, and not rocking it, since you can create a slight convex surface if you rock the stone, or have really thick SiC powder that doesn't allow flat lapping. Food for thought.
  3. Long, sweeping arcs/figure-8s will get things done quickly. Remember to keep things lubricated enough for easy SiC powder movement, since the grit needs to move freely over the surface to cut efficiently.
Here are some pics through the process. This was flattened with 60 grit (not pictured, sorry), then dressed with 120, 240, 320, 400, 600 and finally 800 (probably overkill, but going back down a grit is the easy part).

Note how much powder I'm using, how the surface changes at each grit, and how much more the finer grits will clump up, almost like clay.

120
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220
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I should have cleaned off the old powder first, oops.
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Despite many uses, this Cubitron is still going strong
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Process continued:

320
Wetting the paper back to prevent slipping.
I'm using paper of finer or equal grit to the loose SiC powder at each step. In this case, a single piece of 800 grit paper will serve to take me from 320 grit to 800 grit powder.

Between 320-400 grit, you can really see the surface start to flatten out, and become less pebbly. I think you'd see the best surface if you had the patience of a saint, and spent a lot of time (1-2 hours) at 220 or 320 grit, to really flatten the peaks down to meet the valleys. Sadly, I am no saint.
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I try to used pressure on all 4 corners, or a wide, flat palm when my fingers get tired (since I'm holding the camera, imagine my other hand is also on the stone). This distributes pressure equally over the stone surface. If I rock the stone, I'll wear the surface unevenly, and it won't get flat, or it won't all be dressed to the same surface texture.
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400
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600
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Process finished:

800
After lapping, it seems like this is not a totally homogenous stone - some of the lighter inclusions seem to be softer, and were more easily worked away, leaving some pitting on the surface. Not a big deal by any means. The razor will ride on the remaining flat surface, and hone nicely, I believe. I lapped it once previously, and it produced a nice initial shave. I was hoping to restart at 120 grit, flatten down past the pits, and get a flatter surface, and had a little luck by spending more time at the mid grits between 120-400 (to really even out the the lumps left by the coarse 60 grit flattening process). But it's not perfect. C'est la vie, that's just the nature of this particular rock! All in all, $20 well spent, and after some elbow grease, I'd say it's worth at least $10 now!

If anyone has lapping tips, tricks or insights, I'd love to hear them. I'm always learning too. Hope this helps beginners hoping to get started. It's much faster to use powders than other methods I've tried, much more economical, and also leaves a much more homogenous surface with no striations, as opposed to sandpaper alone, or diamond plates.

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Well done and nice write up!

Pretty much the way I do it or very close.

I do finish on a well worn Atoma 400 or 1200 depending on the finish I am after or the particular stone. I find it easier to get as flat as possible with the Atoma diamond plate. Othereise I do the same.

Cheers!
 
Yup, 60 grit wet and dry is nothing like loose 60 grit Silicon Carbide. You will go through a box of Wet and Dry and hours of grinding.

My experience is that once flat, you can run up the grits quickly.

For me the trick is a steel Dollar Store cookie sheet on flat cement floor, I lay a 24X20 inch piece of 1.25 inch granite counter top, ($5 from Habitat for Human on the cement floor. And on your knees, use your body weight on the stone.

Mark the stone with a grid from a wide sharpie and stay on the loose silicon carbide, 60 grit until you can erase a grid completely in less than 10 laps.

Pencil will wash off quickly with slurry and you are not close to flat, Sharpie must be ground off. I usually do a sharpie grid 4-5 times before I am satisfied the stone is flat. A new stone should not take more than 15-20 minutes to get flat.

Remove the deep 60-grit scratches with 80 and once all the 60- grit scratches are gone, you can polish up the grits quickly, switching to 600 wet and dry paper and up to 1 or 2k. Take one side to 600 grit the other to 2k and burnish.

The trick is flat with no scratches. Dead flat is not necessary, you want the stone smooth, so as it wears, no rough spots or scratches pop up ruining an edge. If you feel the slightest rough spot while slowly honing with a little pressure, you need to re flatten, no cutting corners.


Test you stone with a piece of 600 wet and dry on a flat surface, a sharpie grid should be removed in less than 10 laps.

Like I said the work is in getting to flat with lose 60 grit and removing 60 grit scratches with 80 grit.

I like your sandpaper method, will have to give it a try for loose 60 grit Silicone Carbide.

The steel cookie sheet will not wear and contains the slurry, I use a lot more water than you do and add grit, teaspoon at a time when it feels like it is not cutting.

Once your stone is flat and at 600 grit finish, you can change finishes easily in a few minutes.
 
Yup, 60 grit wet and dry is nothing like loose 60 grit Silicon Carbide. You will go through a box of Wet and Dry and hours of grinding.

My experience is that once flat, you can run up the grits quickly.

For me the trick is a steel Dollar Store cookie sheet on flat cement floor, I lay a 24X20 inch piece of 1.25 inch granite counter top, ($5 from Habitat for Human on the cement floor. And on your knees, use your body weight on the stone.

Mark the stone with a grid from a wide sharpie and stay on the loose silicon carbide, 60 grit until you can erase a grid completely in less than 10 laps.

Pencil will wash off quickly with slurry and you are not close to flat, Sharpie must be ground off. I usually do a sharpie grid 4-5 times before I am satisfied the stone is flat. A new stone should not take more than 15-20 minutes to get flat.

Remove the deep 60-grit scratches with 80 and once all the 60- grit scratches are gone, you can polish up the grits quickly, switching to 600 wet and dry paper and up to 1 or 2k. Take one side to 600 grit the other to 2k and burnish.

The trick is flat with no scratches. Dead flat is not necessary, you want the stone smooth, so as it wears, no rough spots or scratches pop up ruining an edge. If you feel the slightest rough spot while slowly honing with a little pressure, you need to re flatten, no cutting corners.


Test you stone with a piece of 600 wet and dry on a flat surface, a sharpie grid should be removed in less than 10 laps.

Like I said the work is in getting to flat with lose 60 grit and removing 60 grit scratches with 80 grit.

I like your sandpaper method, will have to give it a try for loose 60 grit Silicone Carbide.

The steel cookie sheet will not wear and contains the slurry, I use a lot more water than you do and add grit, teaspoon at a time when it feels like it is not cutting.

Once your stone is flat and at 600 grit finish, you can change finishes easily in a few minutes.
I was surprised the first time I used 60# SiC powder. The scratch were deep and three powder was very fast, I only use it on really messed up stones or hard Arks(which I hope I won't ever have to do again). From anything softest than that I use 220# SiC powder to start and issuance stop at 600# and will use a worn out cheap Chinese 1k# plate to buff/ condition the surface, sometime a harder stone or an old fine India after depending on the stone.
 
I didn’t get any 80 grit with my set, only 120. I think that would be really nice to help set the surface up. I do agree that once you’re flat, running up the grits shouldn’t take too long. I think this stone in particular just has some soft spots, and it’ll never get a 100% level surface.

You don’t think dead-flat is necessary? That’s generally my aim.
 
Yes, you want it flat, and smooth, but you do not need to obsess. trying to get to Surface Plate quality, “Dead Flat.” You probably do not have the equipment to calibrate the surface anyway.

But if the surface is not “perfectly” flat the razor will just ride on the high spots. I doubt that none of our stones are Dead flat or remain flat if they were.

A smooth surface is what you want and obviously reasonably flat.

In the lower grit it is much easier to remove previous stria if you make smaller grit jumps. Just make sure you remove all the previous grit stria before moving on.

You can also get a finer stria pattern if you lighten up on the pressure for your final laps on a grit, same as when honing. This will make the stria pattern shallower and the transition easier.

Bottom line is a smooth stone. If you slowly slide the razor on the stone and feel the slightest bump, that is the edge hitting a scratch or rough spot. It must be removed. You remove a scratch or divot by reducing the level of the whole stone to the depth of the scratch.

It’s a lot of work, but with the right progression it is not that bad, once done correctly the stone face is good for life for honing razors.

An Ark edge is a unique razor edge one of the best edges on can put on a razor, equal to a Jnat edge. It is worth all the effort to prepare a stone.
 
This is pretty much how I do it too. My final finishing is on plain WD paper. I use a granite surface plate as the substrate.
 
Awesome post, @captaincaed - thanks for posting! Not sure if I have ever actually seen SIC powder.

I like your method of sprinkling the SIC powder onto the wet/dry paper. I have only ever used wet/dry on a marble slab. Thanks to your post, I now realize that I can simply supplement my existing method with the SIC. How smart is that, right?

That said, I would not go as fine as 800. The "factory" finish on my Dan's translucent seems perfect to me, so I asked Kim who said that Dan's uses 90-grit SIC to lap the soft and hard Arks, and then a combination of this recycled grit plus some fresh 90-grit SIC to lap the black and translucent Arks such that it is very difficult to put a number on the grit that they use to lap the black and translucent Arks.

For the record, the first time I lapped my Dan's hard black I went to something like 1200 :). This stone is now down to 240.
 
Nice job. Wow you did it inside? I usually do that out in the back yard on a block of granite on a wood table and a hose. So it is easy to clean. My wife would kill me if I did that in the house.
 
I use a similar technique. A clean and lapped granite tile with a piece of glass on top. Sic powder, then wd usually finish on a super worn dtm. Unfortunately my undiagnosed OCD has me checking the stone with a straight edge that has been checked against a certified surface plate. Many years ago a chased an edge for days, turned out my mid range stone was wonky ruining my apex.... maybe I'll work it out in therapy one day. But for know it is obsessively flat for me.
 
Awesome post, @captaincaed - thanks for posting! Not sure if I have ever actually seen SIC powder.

I like your method of sprinkling the SIC powder onto the wet/dry paper. I have only ever used wet/dry on a marble slab. Thanks to your post, I now realize that I can simply supplement my existing method with the SIC. How smart is that, right?

That said, I would not go as fine as 800. The "factory" finish on my Dan's translucent seems perfect to me, so I asked Kim who said that Dan's uses 90-grit SIC to lap the soft and hard Arks, and then a combination of this recycled grit plus some fresh 90-grit SIC to lap the black and translucent Arks such that it is very difficult to put a number on the grit that they use to lap the black and translucent Arks.

For the record, the first time I lapped my Dan's hard black I went to something like 1200 :). This stone is now down to 240.
Kim told me they finish up around 600# when I asked her about the black I bought but I think the flat side on my primitive cut was way lower than that. I don't even think it was flat really. Great stone after some work but the work...
 
Kim told me they finish up around 600# when I asked her about the black I bought but I think the flat side on my primitive cut was way lower than that. I don't even think it was flat really. Great stone after some work but the work...
You only need to do it once.

If it didn’t take so long to lap them, I’d probably have a dozen more by now.
 
I use a similar technique. A clean and lapped granite tile with a piece of glass on top. Sic powder, then wd usually finish on a super worn dtm. Unfortunately my undiagnosed OCD has me checking the stone with a straight edge that has been checked against a certified surface plate. Many years ago a chased an edge for days, turned out my mid range stone was wonky ruining my apex.... maybe I'll work it out in therapy one day. But for know it is obsessively flat for me.
Those really worn diamond plates work awesome for buffing and conditioning a real hard stone like an ark. They're really good for refreshing the surface of washitas to "wake them up" too. I use really cheap ones of ebay because I abuse them badly on many different things but I've yet to need to throw one out. Even after many novaculites, still mainly use the same plate. The back is 400# and not nearly as worn out so it flattens softer stones pretty quick.
 
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