Arkansas Stone Flattening TROUBLE!

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VogonPoet

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Oct 5, 2011
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Please forgive me if this is not in the correct sub-forum. Moderators/Admins feel free to move.

I have a set of cheap-o "Smith's Tri-Hone" Arkansas stones that became dished in the center. They are used with water-based honing oil. I tried to flatten them using a technique recommended by a friend and now 2 out of 3 stones are useless. I flattened the 'coarse' (synthetic, not natural Arkansas like the other two) and 'medium' stones. They are now extremely slick and have no "grit" to them whatsoever. Blades glide over them like glass and no actual sharpening occurs. I did not try to flatten the 'fine' stone at all, though it does need flattening very soon.

I used a 5/8" steel top off of an old table saw as a platform which appeared to be perfectly flat after testing it with a straight-edge. I used a fine-tip sharpie to draw diagonal hash marks across the whole surface each stone as a reference for my progress during flattening. It took 13 sheets of wet/dry 100 grit sandpaper on the coarse synthetic stone and 11 sheets on the medium stone to flatten them all the way (to the point where all sharpie marks were gone). The paper and stones were kept wet and constantly flushed out with water to clear the swarf and loose grit. The stones were moved in a figure-8 motion with very light pressure and the sandpaper was rotated frequently until it lost its grit and was replaced with a new sheet. Also, I was very careful not to mix sandpaper between the stones; each stone had its own sandpaper so as not to "contaminate" one stone with the swarf from another. It took a total of 7 hours to complete both stones (does this seem excessive?). The coarse stone is easily 1/8" shorter and the medium is 1/16" shorter.

After working a few blades over the stones for a couple hours the glassy smoothness did not clear up and the stones were completely ineffective. I suspected the pores of the stones were clogged with swarf from the flattening process even though they were kept thoroughly flushed for the whole process. I've used WD-40, acetone, denatured alcohol, and water-based honing oil with both an electric toothbrush and a regular nylon brush to try to restore the stones but none of them helped at all after a few hours of work. I got a bit desperate after some fruitless research and tried refinishing them with 60 grit sandpaper and even used a copper wire brush in an electric drill to try to reestablish some kind of surface but they are still smooth as glass and will not sharpen at all.

As it stands right now, the 'fine' stone that i DID NOT flatten is several times coarser than both the 'coarse' and 'medium' stones that i DID flatten, just to give you an idea of how slick these stones are. Neither will slowly soak in my water-base honing oil like they usually do, but instead float the oil across the surface and will not allow it to penetrate at all.

I'm stumped, guys. I am not a wealthy man, so I hesitate to splurge on a large diamond stone or a lapping stone to try flattening again. However, if that turns out to be my best option I would consider it.

Ideas? Did I screw up some part of the flattening process? Do I need to start over with a different technique? I'm up for anything at this point.

Thanks in advance, and sorry for the long-winded thread.
 
Vogon, Welcome. Wow! What a first post. I think you did the lapping/flattening part right and your stones are not messed up. But now a different finish needs to be returned to their surface and just how to do this I thought you were on the right track with 60g paper or 36g. Before you go any further give some others time to reply to your topic and see what may surface. DM
 
I haven't tried lapping an Arkansas stone. But, the little bit of reading I've done on it suggests that the most successful attempts at it have been done with diamond plates (coarse ones). The thing about wet/dry sandpaper is, silicon carbide is known for 'fracturing' to smaller particle size with use. In effect, even though you might start with 100 grit, the effective grit will get much, much finer as it's used. I'd imagine it would happen very quickly, when sanding/lapping a very hard stone. It'd essentially be the same as polishing a rock (it is the same, assuming the stones are truly natural). With diamond, being that it's many orders of magnitude harder than silicon carbide (or just about anything else), and it also won't fracture in size, like SiC, it should be more predictable in the finish left behind.

At a minimum, I'd get in touch with Smith's, to ask them what they recommend for flattening these (if anything). Might also see if they'd be willing to re-finish them, even if a fee may be charged for it. Don't know for certain, but it might not even be possible to lap them, without altering the finish at least a little bit. Assuming the stones are truly natural, they might've just been cut/sawed flat initially, without any further refining or finishing. Natural stones have their own character, as is, and I think most are produced and used with that in mind.
 
Lots of folks have their own methods for lapping different stones, my personal experience is that sandpaper, diamond plates etc are not the best methods unless you're lapping a waterstone. Having gone a bit too far with some of my own stones including an Arkansas or two I can say the best method to bring them back or flatten/deglaze them in the first place is to use a loose grit on another (flat) stone - preferably silicone carbide or AlumOx. The cheapest of hardware stones will work for this and generally I use a tile rubbing stone from the tile tool wall at Home Depot (looks like a hefty combination SiC stone, and it is).

For a loose grit I use some silicon carbide grit that is made for lapping gang reel mowers for golf courses, comes in a water-based gel. Valve lapping compound will work too, but many of these come with a grease that is not welcome in your case. The 120 grit works great for restoring a coarse stone, and 220 grit will do a nice job on the fine stone and because it breaks down with use you can use the 220 grit on the finest of stones, though something a bit smaller would be nice for your polishing grade stones. Just add some fresh grit when it breaks down, or keep using it if a finer finish is desired. I lapped a one side of a fine Spyderco to a very nice surface using 600 grit SiC and it will now produce a hair whittling edge while the unlapped side still shows some grind scratches.

Email me if you're not in a hurry and I can send you some 120 and 220 grit compound. You can get a wide range of graded SiC grit at any lapidary supply house (arrowhead is where I got some of mine). Aside from this, you could just go to Home depot and use the rubbing stone by itself (about 8 bucks I think) with a bunch of soap and water. I've had some luck with this, but nothing works better than a loose grit. Sandblasting grit might work too, but I've never tried it.
 
I used a coarse diamond and coarse and fine SiC stones to lapp/flatten my Arkansas stones and they came out fine. I may have not rubbed them as long as you did yours. I used water like you did as well. Some here have used a flat, rough sidewalk with good results. So, diamond is not necessary. Plus, I've lapped other type stones as well with good results too. Like AO and ceramic. Which I didn't mind if they went finer. Just restore the coarseness some and they should work. DM
 
Find a relatively flat section of sidewalk with a evenly brushed surface finish. Wet the concrete and use a figure 8 pattern until flat. Should not take more than a few minutes unless severely dished.

It's the way I always did it and never had a issue.
 
VogonPoet said:
After working a few blades over the stones for a couple hours the glassy smoothness did not clear up and the stones were completely ineffective. I suspected the pores of the stones were clogged with swarf from the flattening process even though they were kept thoroughly flushed for the whole process.
Click to expand...

Think of the classic French polish used by refinishers (like me on occasion) on furniture, and pore filling. The lubrication allows the crystalline structure (in my case pumice, in your case sand paper) to flow into the pores cleanly and stay. You can polish pumice so well into a porous wood like oak using mineral oil that you cannot get it out!

My guess would be that your industrious efforts broke off the aluminum oxide crystals (if metal or mulitpurpose sandpaper was used) or the garnet (if wood sandpaper) and deposited it into the pores, rubbed carefully in by you. Worse, the crystals can be lodged into place by using stereated sandpaper. Stereates are a soapy substance used to help keep the sandpaper cutting surface from clogging, but can easily be left behind on the work surface. I have had to clean stereates off my work more than once until I found that out. And the cheaper the sandpaper, the more stereates it has to make it seem more efficient.

If I were in your shoes I would quit cleaning by rubbing with brushes, more sandpaper, or other stones. If the stones won't cut now, you shouldn't be pushing more material into the pores or rubbing the clogs in deeper.

I think I would take them down to the car wash and simply blast out the pores with soap, the blast them clean with a rinse. It's cheap, and the water/pressure combo would probably due the trick as I know my personal pressure washer will etch concrete. So getting the nozzle pretty close to the stones should give you enough pressure to clean.

BTW, my buddy that worked as a machinist for years told me he flattens stones as he was taught, and that is with a cheap diamond stone similar to those found at Harbor Freight. He cleans off the stones with a high VOC cleaner like lacquer thinner, toluene, etc., to remove any oils a contaminants. He lets them dry, them resurfaces them while they are dry. A few strokes, the he blows them off with a compressor. A few strokes more, and then a blast of air.

Robert
 
I can honestly say I've tried my darnedest to make these stones work again, following most of the tips on here, another knife forum, and more hours of google searches. I've spent well over a week working on them in my off-time but I've made no progress. Not even marginal improvement. All stones are still perfectly flat like I made them originally, and each method I used definitely removed a good bit of material. Stones are noticably shorter than they were new. Here's a list of what I tried, in no particular order:

- My original 7-hour effort on sandpaper.
- blasted with pressure washer and dried thoroughly, which knocked a corner off of my coarse stone
- Refinish with coarser 40/60 grit sandpaper, both aluminum oxide and silicon carbide
- cement driveway with lapping grit as well as a single layer of coarse sand
- Cheap 6x2" coarse diamond plate
- 6x1.5" tile stone 60/80 grit, both alone and with lapping compound
- cement block with lapping grit as well as a single layer of coarse sand
- cleaned with denatured alcohol and acetone
- rubbed tons of honing oil onto them hoping they would somehow be "recharged"
- blasted with air compressor often on all refinishing attempts listed above
- all above methods were done both wet and dry as necessary and they were kept cleaned religiously

I bet I've got twice as much invested in fixing these stones as what they cost to buy in the first place. They were a cheap set of Smith's, after all. I'm at a point where I don't think wasting more time and money on them is even worth it. Having blasted them with my air compressor and pressure washer from the start I really don't think clogging is the issue anymore. All of the methods suggested here and elsewhere definitely seem like they would work but these stones are just not cooperating. I'm at a loss to explain why. Who knows if they're even 'natural' stones as advertised or some kind of synthetic material that was not meant to be resurfaced? I can't find any technical data on them anywhere.

I've put too much sweat and money into them with no results to justify screwing with them anymore. Time to move on.

Regardless, many thanks to everybody for the advice! ;)
 
Might be worth a call to Smiths - they might set you up with a replacement...Doesn't sound like you did anything wrong.
 
i had those cheap smiths stones for a while too, and after they dished out, i just didn't bother to flatten them. i still have a king 1000/6000 combo stone that i use once in a while, but have mostly gone to 1200 grit over a granite slab or 8/9 leather backing if i want to relax and sharpen by hand. however, i bought paper wheels about a month and a half ago, and it is so far the fastest way to get my knives sharp.
 
I'd still be VERY curious to hear from Smith's, regarding what they do/recommend. There's a good possibility that they'll simply advise replacement, especially since these are 'inexpensive' stones. On the other hand, they might also drop a hint or two as to why these didn't respond as expected. Even if they can't be fixed, chalk it up as a 'learning experience' on your journey to sharpening enlightenment. ;)

I lapped a couple of ceramic hones a while back, and they've also been permanently 'altered' in character. Much less aggressive, but all-the-better for finishing/polishing chores. I've simply reassigned them to a different 'niche' in my sharpening scheme. You might still find some use for your hones, in a similar manner. If nothing else, they could also be utilized as a smooth, hard backing for wet/dry sandpaper, if you were so inclined.
 
I'm still baffled by this. As I mentioned earlier, I bought a Spyderco fine stone with the intention of lapping one side to an Ultra fine, and leaving the Fine side as is. Lapped it with 600 grit SiC on the fine side of a cheap hardware store AlumOx stone, and just a touch with some 1200 grit. I could still see two low spots, but lived with it for a few months. Lapped it down with 220 to get it flat once and for all, and it worked. Just wouldn't produce a high-polished edge anymore - was actually a bit more coarse than the factory side. Lapped it down with 600 and 1200 grit once again and it restored the finish perfectly. I've done this on natural Arkansas stones a number of times - go to fine and the stone won't cut anymore, just sort of glazes up. Every time I've been able to restore it by lapping with a coarser grade of SiC powder. Personally, IMO Smith's should cut a deal or replace the stones.
 
HH,

You mentioned, earlier in the thread, about preferring loose grit vs. a fixed abrasive. It's something I haven't tried yet, but it did make me wonder about the possible differences made by doing so. Same as with sharpening blade steel; the abrasive size, shape, hardness, loose/fixed/bonded, wet 'slurry' or dry, and even possibly the differences in the backing 'stone' for loose abrasives all come into play. So many variables. I used a coarse DMT Duo-Sharp plate to lap my ceramic hone, but sort of wished (now) that I'd tried out the loose grit. I really wonder how much of a difference that'd make, compared to what I've already done. I sort of like how my ceramic hone is now, so I don't necessarily want to change it again (I still have another 'standard' one, as backup). But I am very curious about how it might've been done differently.
 
I have nothing but my own experiences to go by, I've glazed a fine Arkansas stone and both sides of an AlumOx bench stone by lapping with diamond plates. I have no doubt it can be done up to a point because so many other folks report good success, but suspect if one overdoes it you'll have to come back down in grit to reduce the polish. The hard Arkansas just looked better and better up to a point, and then it just wouldn't really "bite" on the steel anymore. I lapped it back down with 120 grit SIC to the point where it looked real dull again, and it recovered its ability to remove metal without leaving little glaze tracks across the stone.

The same thing happened to the AlumOx stone - it refined better and better up to a point, then it stopped biting on the steel and again, left glaze tracks across the stone. My belief is that you need a loose grit to attack the soft (non abrasive) parts of the stone a bit more than the abrasive parts. When you use a flat surface everything gets hit on the same plane and if you go too far you'll polish the thing into a decorative brick even if you're using plenty of water. Again, my IME this only happens with some stones types. I've lapped plenty of SIC stones using just another SIC stone to rejuvenate them a bit and never run into this issue. So far, just natural and AlumOx stones have given me issues. Not sure about the ceramic plates, but the loose grit works so well for me I'm not about to experiment with a diamond plate on my Spyderco or three line Swaty.
 
Informative stuff, guys.
I'm getting the clear message that when it comes to lapping stones (a new concept to me) that less is more.
Good to know.

My question is if it's feasible to intentionally over-lap a stone to make a poor man's xxx fine stone (I
ve noticed that they're very pricey, like a new knife pricey). Or if the reported glass-like surface is too smooth to even serve as an xxxfine ?
 
I've had the same experience as Heavy Hand, using diamond plates, coarse and fine. When lapping Arkansas and AO fine India stones. They can be brought back with loose grit. Pointy, they will only get 'SO FINE' and cease getting finer. The rest is glaze which is what you don't want. A Norton fine India a 320g stone may be brought to 6-700g 'feel' (maybe 800). Understand you cannot change the grit of a stone only its surface feeling. Which with this type stone will last a long time. Mine are holding well after 2yrs. of use and show no sign of reverting back to their former texture. The aluminum oxide stone is a good substitute for a hard Arkansas just it can be tricky to lapp. Less initial investment, better cutting and harder. Norton did offer this in a higher grit 25yrs. ago. A higher grit India may still be found at Sticks and Stones. These are Norton made. DM
 
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