Oil Stone Cleaning - how to?

Any ideas on leeching oil out of a stone or additional stone cleaning methods / tips

So I got this "Charnley" stone, which may or may not be a legit finisher, but I got it down to a single figure price which - for me - means it's worth finding out. If it's not, at least it should finish my chisels nicely (or keep a pile of papers in place with the window open). It'll need a lot of truing, lapping, chamfering & polishing (up to 1k ish?) with wet 'n' dry paper and microfinish films, but I like doing that sort of thing.

As you can see from the first photos, it was pretty oily. I wanted to be gentle with it, so after a few hours with a brass brush & some elbow grease, it's cleaned up pretty well. There is still some surface oil to be removed (another hour or so with the brass brush), but what I really want to know is: How to leech out the oil in the stone? Lapping etc will remove some of the oily layer, but I'd like to get as much as possible out before that.

So far suggestions include:

My brother-in-law told me of a popular Scandinavian method to turn an oilstone back to a water stone, involving soaking it in very hot water and detergent for at least 24 hours, until oil leached out to the surface, then repeating this process 4 or 5 times.

Others were:
"soak it in WD40",
"Put it in the dishwasher",
"Burn the oil out" (!?!),
"Soak it in white spirit/paint thinner or charcoal lighter fluid",
"Boil it with a rag in dishwasher detergent",
"use oven cleaner and an SE razor blade" and so on.

What kind of preparation would you do?

I've been told elsewhere that that I should just use it as it is (lapped of course), as the final photo shows most of the oil off.

Soak it in Simple Green.

coonskinner said:

Soak it in Simple Green.

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It's extremely expensive here in the UK unfortunately. There is a UK product - "Dettol" - that is very cheap and similar to Simple Green, tho' not as good, but I hadn't though to try that. I suspect the surface will be ok as it is, but I want it to be closer to perfect. I'll look for an inexpensive source of Simple Green here in the UK. There is no hurry, as it's probably been covered in oil a long time.

Lord Fatboy said:

It's extremely expensive here in the UK unfortunately. There is a UK product - "Dettol" - that is very cheap and similar to Simple Green, tho' not as good, but I hadn't though to try that. I suspect the surface will be ok as it is, but I want it to be closer to perfect. I'll look for an inexpensive source of Simple Green here in the UK. There is no hurry, as it's probably been covered in oil a long time.

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any real degreaser will work, you can also try dawn dish soap, just anything made to cut grease or degrease should do the job, i would soak for a while, scrub, rinse, soak. repeat until its all gone.

tetraodon said:

any real degreaser will work, you can also try dawn dish soap, just anything made to cut grease or degrease should do the job, i would soak for a while, scrub, rinse, soak. repeat until its all gone.

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Thankyou. I couldn't wait for advice, so I rushed ahead and ended up soaking it in a cheap degreaser, then scrubbing, then lapping & chamfering. I'm not quite done yet, but because it's such a hard stone, only a tiny bit of oil had penetrated the surface. I think by the time I'm done, it'll equal 10-12 hours at the sink (not including soaking time), but even if it's not a great finisher, I'll have a beautiful rock.

This is the stone, dressed, chamfered and sealed (lacquered). I wanted to use both sides, but lapping the darker side revealed more and more gritty inclusions, so I went with the other side.
Honing distance is around 5 1/2 inches by 1 1/2 inches. The small hole in the centre was full of grit, so I dug that out and sanded it smooth.

All in all, I reckon it took 20 hours at the sink, but it's my first natural and any caveman would be proud of it .

For UK users - "Elbow Grease" seems to be our equivalent of Simple Green. And it's cheap.

or Fairy liquid that's what I use in hot water, but let the stone heat up slow or it could crack.

Ice-Man said:

or Fairy liquid that's what I use in hot water, but let the stone heat up slow or it could crack.

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Yes, big fan of fairy platinum too...

I'm familiar with stones. I usually soak in isopropyl alcohol. It will evaporate very quickly. Scrub with a course brush, not a steel brush. Then wash with the yellow detergent. Don't clean with anything that has a hand lotion component.