Restoring old, heavily used sharpening stones...

C

Clan Gunn

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Oct 28, 2012
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Have a number of older, heavily used sharpening stones that I would like to restore and put to use. These run around 8 X 2" and 6 1/2 X 1 3/4" plus a smaller one. One had a box with India Oil Stone printed on it. Believe these where used with an oil for sharpening wood working chisels and plane blades. Some are two sided, most are hollowed out. I borrowed a UA Sait #25050 handled brick (8 X 3 1/2 X 1 1/2), slow going. Even tried a used 6 X 48" belt, also slow. How should I attack this problem and how to dell with the gumming up of both the Sait and old stones?

Thanks in advance. A starting step towards sharpening knives, then carving tools, turning tools, plane blades,...
 
Clan Gunn said:
Have a number of older, heavily used sharpening stones that I would like to restore and put to use. These run around 8 X 2" and 6 1/2 X 1 3/4" plus a smaller one. One had a box with India Oil Stone printed on it. Believe these where used with an oil for sharpening wood working chisels and plane blades. Some are two sided, most are hollowed out. I borrowed a UA Sait #25050 handled brick (8 X 3 1/2 X 1 1/2), slow going. Even tried a used 6 X 48" belt, also slow. How should I attack this problem and how to dell with the gumming up of both the Sait and old stones?

Thanks in advance. A starting step towards sharpening knives, then carving tools, turning tools, plane blades,...
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First step might be to soak them in some oil and see what leeches out overnight. My gold standard for reconditioning most stones is to get your hands on some 80, 120 or 220 silicon carbide lapping compound. Is used for gang reel mowers on golf courses, valve lapping, if you can't find any I could send you a cup or so. Pick up a tile rubbing stone from Home Depot, or a cheap hardware store combination stone that's pretty flat. Make a paste out of the lapping compound, a lot of dish soap, and some water - make it kind of thick. Face the stones to each other and lap away, circles, figure 8s, switch hands, ends etc. As the siliconcarbide breaks down, add some fresh grit and keep working till it cleans up. Once it gets pretty close (you'll see the high spots slowly working down), clean it off and lay out a grid with a thick pencil and give it a few more minutes work till all the lines grind off. Rinse and do the other side. Is easier than it sounds on most stones.

Martin
 
I would first put them in a pan of soapy water and slowly heat it to boiling. I do it in an oven when my wife is out of town. The water cannot get hotter than 212 (boiling). When the water is boiling turn the oven off and let it soak. Do this a few times and you will leach out all of the oil. Don't do it when your wife is at home, trust me.
 
HeavyHand (aka Martin), thanks, you are a class act. Pondoro2310 thanks for keeping me out of the dog house. So these are worth saving. There's also a small stone that seems very hard. The carbide stone is a little early and I need to remove the oil first. I was getting ready to attack the stone with a disc (7") grinder.
 
I'd stay with sandpaper on a plate of glass to flatten them. You want them flat. Chisels are hard on a stone but you can bring them back. Getting the oil out will help.
 
Clan Gunn said:
HeavyHand (aka Martin), thanks, you are a class act. Pondoro2310 thanks for keeping me out of the dog house. So these are worth saving. There's also a small stone that seems very hard. The carbide stone is a little early and I need to remove the oil first. I was getting ready to attack the stone with a disc (7") grinder.
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Am glad to be of help! I've lapped quite a few stones and pooched the job on a couple of them, learned a lot from having to go back and fix those...

Best single advice is to use plenty of water, oil, soap etc - make sure the grit can move loose and there's some sort of lubricant, or there's a real good chance the stone will glaze.

Martin
 
I had a couple big old stones that needed some heavy work. They were badly chipped all around the sides, and dished quite a bit. I tried the sandpaper, silicon carbide stones, etc., but it was just taking way too long. I had a lot of material to remove. So I took 'em out on my back porch, kneeled down, and rubbed them against the concrete using both hands & putting my shoulders into the work. This finally let me make real progress, and I had 'em trued up in no time.

I tried boiling a stone to get old oil out of it, as mentioned. It got out some, but not much. Wayne Goddard wrote about this problem in Blade some time ago- he soaks old stones in Simple Green cleaner (or various generic versions of it) to get the gunk out, and I've taken to doing the same. Simple Green is also great to use as the lube on water stones or sandpaper- I have found it keeps the stone from clogging much better than water does, and does not cause rust as quickly as water.
 
the possum, "I had a lot of material to remove. So I took 'em out on my back porch, kneeled down, and rubbed them against the concrete using both hands & putting my shoulders into the work." Tried this some years ago, you did way better than me. Thanks for reminding me about Simple Green.
 
I like soaking in lacquer thinner. The stuff will take everything out. Just keep it out side.

Lapping harder oil stones is a lot easier with lots of water and loose grit, like HH said. Get a granite tile and your base.
 
Gah, that was poorly written. Lets see if we can try this again. Get a concrete foot path paver. Should be something to the tune of 12" X 12". Splash water on it followed by a handful of sand. Rub well, in the random motion described before. And add sand often. I think that will be satisfactory but it probably runs higher a chance of glazing the stone. YMMV.
 
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the possum said:
I had a couple big old stones that needed some heavy work. They were badly chipped all around the sides, and dished quite a bit. I tried the sandpaper, silicon carbide stones, etc., but it was just taking way too long. I had a lot of material to remove. So I took 'em out on my back porch, kneeled down, and rubbed them against the concrete using both hands & putting my shoulders into the work. This finally let me make real progress, and I had 'em trued up in no time.
I tried boiling a stone to get old oil out of it, as mentioned. It got out some, but not much. Wayne Goddard wrote about this problem in Blade some time ago- he soaks old stones in Simple Green cleaner (or various generic versions of it) to get the gunk out, and I've taken to doing the same. Simple Green is also great to use as the lube on water stones or sandpaper- I have found it keeps the stone from clogging much better than water does, and does not cause rust as quickly as water.
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I've had good success rubbing them on concrete as well. Use lots of H2o. DM
 
Did the re-cycle thing with 63 lbs. of wrought iron and was paid $4 plus. The day was not a loss though, someone came in with a bunch of junk and I grabbed a metal pot. Have the old sharpening stones in hot water w/soap. Still may try the paint/lacquer thinner.
 
Some of the knife makers would have paid you a LOT more than that for wrought iron!
 
Gunn, It may seem like a lot of elbow grease to get your stones back in good working order but they'll be good for some time and you'll not allow them to get in this shape in the future. Plus, you'll learn a lot doing this. They'll still give you many years of service and result in good sharp knives. DM
 
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