Soft VS "Hard" (not True Hard/Black/Transluscent) Arkansas Stones

[Andrew Pitonyak]

I have a couple of old stones I acquired on a bundle and none of them are flat. I just wondering would you try to make them flat or use as is?

Although I spent significant time looking at how people recommend flattening Arkansas stones, I have never done it myself because none of my Arkansas stones are out of flat and the ones that I did buy that were out of flat turned out to be misrepresented and were not Arkansas stones and not worth flattening.

It was my intent to to use loose carbide on a glass plate to do it (with water), but I have seen (in videos) people do it on concrete. If mine were out of flat, I would start with one to see how it went and go for it. One concern is that you are indeed introducing scratches and then the question becomes, how fine should you go after flattening the stone. I know that for a while, it was recommended that you purchase a nice Washita stone and then lap the two different sides at different grits so that they would cut differently. So, understand that if you do lap these stones, you may end up changing the cutting characteristics. I have zero experience with this, it is just something that I expect to happen. This was mentioned in passing in a previous post.

"Best Arkansas Stones" (A brand / company) looked at scratch patterns to find equivalent "micron" sizes for their stones (this is or was on their web site, no idea if it is still there), but, they claimed

• soft = 12 micron = 1200 grit
• Hard = 10-11 Micron = 1500 Grit
• Black = 7 - 7.5 micron = 2300-2500 Grit
• Translucent = 5.5-6 micron = 3500-4000 grit.

I should use the "approximate" symbol rather than the "equals" symbol, but it is not on my keyboard and the non-scientists or mathematicians in the group probably prefer to see =.

I do own a sets from Preyda, Dan's, and Best. Nobody agrees on "equivalent" grit. Preyda claims:

• Soft = 400 - 600 grit
• Hard = 600 - 800 grit
• Hard Black = 2000 - 3000 grit
• Translucent = 4000 - 6000 grit
• Surgical Black = 8000 - 1000 grit

Then Dan's steps in and says (listed in order of what they think will leave the finest edge):

Soft = 400 - 600 grit
Hard = 600 - 800 grit
True Hard = 1200+ grit
Translucent = 1200+ grit
Black = 1200+ grit


Preyda and Dan's both agree that their finest stone is not the translucent. I own only a few translucent stones.

I have had good luck with all of these stones but the general consensus seems to be that Dan's is the fastest cutting (or maybe the best) but I am in no position to agree or disagree with that since I feel that I have too little experience to say this. I have, however, managed to get good results from all of these stones. Initially I had poor luck with my Best stones so I bought some Dan's stones and received advice here on how to use them and then I started seeing good results from all of them. Oh, I have also had pretty good luck with a stone that I accidentally purchased that the seller called a Washita but does not look like any washita I know. It seems to cut similar to what I expect from a Washita. I realized immediately I had purchased the wrong stone but it is one of my favorites; go figure!.

[Luke Dupont]

You can flatten softer Arkansas stones with a diamond plate, but it will wear out over time, and it will wear out VERY quickly if you try to flatten a transluscent or surgical black.

A very easy solution is to take two coarse (india or carborundum for example) stones, rub them together to make them flat, and then rub them on your Arks. I usually do this with a coarse india and it seems to work just fine, even for the hardest arks.

Sand paper on a flat surface, or better yet silicone carbide are options as well.

The stone will initially cut more coarsely after this, but it will quickly wear back into its natural grit if you sharpen often.

I find that I like to leave my surgical blacks with scratch patterns straight from the coarse or fine side of the India, though... Something about a scratched up surgical black allows it to cut faster but still fine, and I think there are a number of other people who notice the same thing.

As for grit and the edges left by Arks, you can't really equate scratch patterns and grit to edge fineness, because arks cut very, very shallow grooves -- much shallower than a diamond plate or man-made stone.
So, even if a Soft might technically be something like 400-600 grit, the edge you get is going to be *MUCH* finer than that, and the cutting speed equally slower -- more in the 1500-2500 range for a Soft Ark in my experience. And I'd put a Hard at more like 3000-5000, with the hardest and finest Arks being well above 10k in "effect". But there is no equivalant grit, really -- they cut differently and leave a very different edge compared to any synthetic stone, and even to many other natural stones. Taking a blade to a bare leather strop reveals just how fine an edge Arks tend to give, as the shallow scratches can be easily refined on just plain leather.

[Rafael Herrera]

I tried lapping a Washita stone using sandpaper and it took a long time. It also created a lot of dust that it was probably pretty bad to breath. A diamond stone may also take a long time and the stone may end up worn out.

Lee valley sells silicon carbide lapping grit. The coarse powder, 90 grit, on a piece of float glass and water will wear any stone very quickly, not just a Washita. For finer stones, 180 grit will smooth the surface.

It's nice to refurbish an old stone and fit it in a new box.

20200101_222040.jpg

[steven c newman]

Hmmmm, with all this constant sharpening...where does one find the time to actually USE the tools? Is there any shop time left to work on a wood project?

I usually schedule a day between projects, to refresh edges. Just normal maintainence....usually am doing any rehab work at the time, too.....while waiting on the next project to start.

IF I do stop during a project to refresh an edge...usually only 10 minutes, then back to work. YMMV

[Andrew Pitonyak]

Nicely stated Luke, thanks, lots of information there.

[Andrew Pitonyak]

Hmmmm, with all this constant sharpening...where does one find the time to actually USE the tools? Is there any shop time left to work on a wood project?

I usually schedule a day between projects, to refresh edges. Just normal maintainence....usually am doing any rehab work at the time, too.....while waiting on the next project to start.

IF I do stop during a project to refresh an edge...usually only 10 minutes, then back to work. YMMV

Especially with my knives, I have a tendency to get it really sharp and then cycle through them until I realize.... this thing is not sharp. And then I have a large stack to sharpen.

With my woodworking tools, I am more likely to do the fast touch-up while working. With my Shaptons, I rarely have to flatten. With my Arkansas stones, I even less rarely have to flatten (as in have not done it yet one one I purchased new.... or used).

No wait, what I really mean is that I never work wood. I just keep stropping looking for that perfect shaving edge!

[Eric Rathhaus]

I don't know how you have time to sharpen, Steven, with all the time you spend posting snarky comments on various forums.

[Jim Koepke]

I don't know how you have time to sharpen, Steven, with all the time you spend posting snarky comments on various forums.

LOL!

My sharpening tends to be done as needed. It only takes a few minutes to disassemble a plane, hone the blade, reassemble the plane and get back to work.

Maybe a little longer if a jug needs to be taken to the nearest faucet to use the water stones.

jtk

[steven c newman]

Tends to happen when one is chair-bound...hard to just sit around all day, unable to even get TO the shop.....tends to make one a tad bit...grumpy......

As for "snarky"? I return snarky for snarky....

Hmm, managed to get to the shop a bit ago....rehabbed 2 block planes....irons in both are OEM....and are sharpened back up to 600 grit...for now. Too sore to go out on a Quest for the Perfect Edge. One hour, counting "travel time" to the shop and back...was about all the old body could handle. BTW: Unicorn in effect.....Film if and when I can get back up out of this chair, waddle down the steps to the shop, and take a few pictures...may do a "Before & After" thing....

Sharpening Threads...never fails......

The Unicorn Machine...
Unicorn Machine.JPG
Old 6" Craftsman grinder...Brass wheel on the right, cloth wheel on the left...green stick to "charge" the cloth wheel up.

[Luke Dupont]

I usually sharpen as I need during work, but occasionally when I need stress relief, I'll go through my tools and knives and sharpen everything up.

I don't find it to be that big of a chore to pop the tool on a stone or two for a few minutes, but it can disrupt work when you have to sharpen a plane iron and then you also have to readjust the plane to take the right shaving again.

But, I confess to being one of those sharpening geeks who find some zen and relaxation in the process...

[Robert Hazelwood]

Re: Flattening an arkansas stone

I would not try to do it with a diamond plate. They are good for refreshing the surface of a flat stone if you want it to cut faster. But they are too slow for flattening a stone that is out to any significant degree. I would use coarse loose diamond or SiC grit on a flat surface, or 80 grit PSA sandpaper stuck down solidly to a flat surface and changing the paper often. If the stone is way out of flat, you can use the idler wheel of a belt sander to take off the high spots before lapping. I think David Weaver has a of video doing this.

I do not have a "Hard" Ark. But I do have a big Soft from Natural Whetstones and think it is great. I rub it a bit with a 320 grit diamond stone to keep it faster cutting and it seems to me like the perfect medium stone- cuts fast enough to establish good geometry but leaves a fine enough finish that the finishing stone can easily polish. I imagine most "hard" arks are more or less similar, especially if you abrade them regularly. If you let them settle in (don't abrade) then they should get a little finer than a Soft, and in that state may be a good finish stone.