Oil stone grit?

[Luis Reyes]

Hi All,

I found four oil stones on Facebook marketplace and bought them without doing much research. How do I know what grit they each are? The fourth one (light colored) I don’t think is very good as I found a $1.99 sticker on it.

I was thinking maybe darker to light would be coarse to fine grit? Should I just try this on an old chisel and see what happens?

thanks in advance!

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[Jake Hillestad]

Color is pretty meaningless without knowing brands. Even then, no guarantee.

Best bet is sharpening something with them and taking note of the scratch pattern produced.

[Jim Koepke]

Those look like what Norton made and labeled Crystolon.

They vary from coarse to sort of fine. On one in my shop like your light grey/dark grey stone is very coarse.

The other one that looks a little brownish may be a Crystolon India stone which is still coarser than a polishing stone.

As Jake mentioned, "sharpening something with them and taking note of the scratch pattern," may be your best way to rank their relative grit ratings.

jtk

[Rafael Herrera]

Hard to tell what the two on the left are, they look like coarse stones. The two on the right are "combination stones", they typically come in coarse/fine or medium/fine grits. The actual numbers are kind of meaningless since each manufacturer uses a different recipe. They are meant for around the house or farm kind of sharpening: axes, machetes, cleavers, lawn mower blades, etc. You use the coarse side to repair a damaged edge, the fine side for regular sharpening. For woodworking tools sharpening, a finer stone than these would be more appropriate as a finishing step.

[Mel Fulks]

Some of the low end coarse stones I bought as a kid were coarse enough …but didn’t cut metal. Finding a cheap used stone that is well
worn means it will cut.

[Eric Rathhaus]

The first two also look like they're covered in dirt, filings, oil and other detritus. Some don't do this, but I soak the used stones in hot water with a good degreaser added. You'd be surprised what the stone looks and feels like after a good cleaning.

[Luke Dupont]

The one with an orange side on it looks like a combination India stone. I really like Norton's India stones. You'll probably want to follow up with a finer Arkansas stone or a strop to get a really keen edge, but they're a great first step in a two stone set up.

Make sure to clean them well and maybe dress them with a 300 grit or less diamond plate -- use sandpaper or something for flattening, and the diamond plate just to rough up the surface. If an oilstone gets too "smooth" on the surface, it will cut much more slowly than it should. Dress it nicely and it's pretty much every bit as fast as a waterstone.

[Rob Luter]

At the end of the day, the grit number is meaningless. What matters is if they cut, how well they cut, and what kind of finish they leave.

[Maurice Mcmurry]

Last month I picked up a stone from Whetstone Creek. It was in the creek not in the abandoned quarry. It is a lousy whetstone but has potential as an oilstone. Judging by feel I guess it to be around 1500 grit.

I laid out several sheets of wet or dry sandpaper and rubbed my fingernails for comparison. This rock feels similar to 1500.

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[Luis Reyes]

The one with an orange side on it looks like a combination India stone. I really like Norton's India stones. You'll probably want to follow up with a finer Arkansas stone or a strop to get a really keen edge, but they're a great first step in a two stone set up.

I tried this one first and it does seem pretty coarse. It did a quick job but definitely will need something smoother next!

Thank you all for the tips, pretty excited to try the other ones!