History of Whetstone Use

[cotedupy]

Reading through some old threads I noticed some... err... 'spirited debate' on occasion, some of which revolved around the historical use of sharpening stones. So here, in case it's of interest to anyone, are some bits of history...

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The world's oldest known whetting stone is at least 65,000 years old, and it's Australian. Aboriginal peoples at the time were easily the most advanced humans in the world, no other culture is known to have sharpened the edges of stone tools in this way for the next 20,000 years.

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Oil has likely been used on sharpening stones for at least 6,000 years. This coincides with a rough estimation for the first cultivation of olives for production of oil in the Mediterranean, the oldest surviving oil amphorae date to around 3,500 BC.

The popularity of oil vs water more recently in Europe was probably actually dictated by geography as much as anything else. Most natural sharpening stones can be used well with either, and availability would have been the largest contributing factor to what was chosen. Sharpening stones from countries further north were more traditionally used with water, further south - with oil.

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The first significant description of sharpening stones in western literature comes from Pliny's Natural History completed in 77AD, in which he makes a distinction between those used with oil, water, and saliva. Many of these stones are not clearly identifiable now, but we can see that even then the Turkish / Cretan oilstone was held in high regard.

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(All that may not be of interest to anyone apart from me, but thought I'd put here just in case!)

 

[D_W]

I don't know much about the history of older whetstones other than to say my window into them opens as one that lasted a very long time was closing (turkish oilstones). I have a cretan - they're still mined, though they may not all be the same as what was written historically, they are fine oilstones that hold shape well but are more friable than hard and trans arkansas stones.

The only older turkish that I have is a somewhat irregular stone that's more brown than the characteristic black and it's about as fine as a slurried translucent arkansas and will release particles more easily than an arkansas stone, so with a hard steel and a lamination layer, it keeps itself cutting and wears relatively slowly. They were noted in old texts as being able to cut harder steels well, even though the abrasive is the same hardness as an arkansas stone, a rolling abrasive will cut steel, especially a matrix with carbides - not sure which is giving the actual hardness on a dent test - harder than the abrasive itself.

They are just dandy. I've never found a black one at a reasonable price and almost spent a wad on one that was labeled, dark black with great characteristic lines in it and looked to be unused. But it was 1.5x7", $250 or something, and I just couldn't bring myself to do it. The one that I have, that's probably not as good of quality, but is still very good, was $55, probably because nobody knew what it was.

I think their standards for a hard stone in the old days were a lot higher than now, so when they talk about truing a stone often when it's used heavily, the fine workers at the time would've had little tolerance for a stone that couldn't be maintained flat easily. It rarely needs flattening to stay true, but rarely is maybe 5x as much as an arkansas stone and it will give up its surface maybe faster than that when there is a soft layer of steel on tools to pull of particles.

When we stopped using wrought and fairly soft backs, we lost this. If you have a wrought japanese tool, you will find something like a washita is suddenly a lot more snappy in sharpening and the ability to really keep it "fine and dull cutting" isn't there. The visual effect is nice.

(got stuck in my bubble talking about the turkish - it would've been a very practical fine stone)

Before that, I've not looked back much - this kind of topic and what was sharpened is interesting, though. I've had a fair number of tools that are from the early 1800s and they're a little softer than mid to late 1800s when the washita became widely distributed. I think the use of a sandstone to maintain the full bevel and probably some type of lower cost stones for most workers (the turkish would've been expensive at the time, and nicholson or roubo or someone in that several hundred year period remarked about the decline in quality and the cost for what you get)....probably those low cost stones were more similar to a hindostan now, and they struggle to cut steel that an arkansas stone will cut pretty well.

More surface finishing without much abrasive follow up probably also biased toward having edges undamaged, which favors more frequent sharpening, too.

It's hard for me to grasp whetstones from several thousand or tens of thousands of years ago without knowing what the tools were made of, how hard they were, and whether or not the objective was the same (e.g., was it more common to abrade an edge and then burnish or work harden the apex). It certainly is the case that the oft described damascus steel had large visible carbides in it (that polish shiny dots), which we wouldn't like now because it would make the steel hard but not very tough.

There's some lack of much sample size when looking back that far that I kind of fall off on - proof is nice so that broad conclusions aren't changing with the finding of one or two new samples.

 

[Jacob]

Metal tools didn't start until the bronze age about 5000 years ago but I'd guess whet stones were in use continually since your 60000 year old example.
Oldest known polished stone axe (i.e. "whetted" with another abrasive, presumably a stone) perhaps 45,000 years old Oldest known axe discovered in Australia, claim researchers
There's a lot in "The Wood Age" by Roland Enos about early tools and the development from wood to wood and stone. He says polished axes were not just symbolic but were highly functional as timber splitting mauls as they split better than sharp riven cutting edges. Kind of obvious really! He even mentions sharpening angles - 35º for a polished stone maul - but the edge itself not necessarily sharp as the split runs ahead of it. He reckons the ability to fell and to split (rive) timber was an industrial revolution in itself. It's a really interesting read - quite short and packed with information.

 

[cotedupy]

Metal tools didn't start until the bronze age about 3000 years ago. Oldest known polished stone axe (i.e. "whetted" with another abrasive, presumably a stone) perhaps 45,000 years old Oldest known axe discovered in Australia, claim researchers

Ah interesting, I hadn't seen that!

So the picture I posted above came from a finding just a bit after that, in 2017. Which was why the caption says it had 'rewritten the history of Australia' - pushing the date of the earliest migration back by about 20,000 years.

https://www.smh.com.au/technology/a...the-history-of-australia-20170719-gxe3qy.html

 

[raffo]

Before the start of metal use, certain tools were made of stone and volcanic glass.

Stones like cherts (or novaculite) that fractured the way they do produced edge tools. The skill to shape stones by ancient cultures is remarkable. Other stones were abraded to shape using other stones.

In Peru, the Incas used polished stone tools. Their expertise in shaping stones for tools (or weapons) and architecture was amazing.

(edited, added stone tools picture)

 

[cotedupy]

I don't know much about the history of older whetstones other than to say my window into them opens as one that lasted a very long time was closing (turkish oilstones). I have a cretan - they're still mined, though they may not all be the same as what was written historically, they are fine oilstones that hold shape well but are more friable than hard and trans arkansas stones.

The only older turkish that I have is a somewhat irregular stone that's more brown than the characteristic black and it's about as fine as a slurried translucent arkansas and will release particles more easily than an arkansas stone, so with a hard steel and a lamination layer, it keeps itself cutting and wears relatively slowly. They were noted in old texts as being able to cut harder steels well, even though the abrasive is the same hardness as an arkansas stone, a rolling abrasive will cut steel, especially a matrix with carbides - not sure which is giving the actual hardness on a dent test - harder than the abrasive itself.

They are just dandy. I've never found a black one at a reasonable price and almost spent a wad on one that was labeled, dark black with great characteristic lines in it and looked to be unused. But it was 1.5x7", $250 or something, and I just couldn't bring myself to do it. The one that I have, that's probably not as good of quality, but is still very good, was $55, probably because nobody knew what it was.

I think their standards for a hard stone in the old days were a lot higher than now, so when they talk about truing a stone often when it's used heavily, the fine workers at the time would've had little tolerance for a stone that couldn't be maintained flat easily. It rarely needs flattening to stay true, but rarely is maybe 5x as much as an arkansas stone and it will give up its surface maybe faster than that when there is a soft layer of steel on tools to pull of particles.

When we stopped using wrought and fairly soft backs, we lost this. If you have a wrought japanese tool, you will find something like a washita is suddenly a lot more snappy in sharpening and the ability to really keep it "fine and dull cutting" isn't there. The visual effect is nice.

(got stuck in my bubble talking about the turkish - it would've been a very practical fine stone)

Before that, I've not looked back much - this kind of topic and what was sharpened is interesting, though. I've had a fair number of tools that are from the early 1800s and they're a little softer than mid to late 1800s when the washita became widely distributed. I think the use of a sandstone to maintain the full bevel and probably some type of lower cost stones for most workers (the turkish would've been expensive at the time, and nicholson or roubo or someone in that several hundred year period remarked about the decline in quality and the cost for what you get)....probably those low cost stones were more similar to a hindostan now, and they struggle to cut steel that an arkansas stone will cut pretty well.

More surface finishing without much abrasive follow up probably also biased toward having edges undamaged, which favors more frequent sharpening, too.

It's hard for me to grasp whetstones from several thousand or tens of thousands of years ago without knowing what the tools were made of, how hard they were, and whether or not the objective was the same (e.g., was it more common to abrade an edge and then burnish or work harden the apex). It certainly is the case that the oft described damascus steel had large visible carbides in it (that polish shiny dots), which we wouldn't like now because it would make the steel hard but not very tough.

There's some lack of much sample size when looking back that far that I kind of fall off on - proof is nice so that broad conclusions aren't changing with the finding of one or two new samples.

Continuing in your bubble of talking about Turkish stones D...

I've had quite a few old Turkish and quite a few modern Cretans, and I am completely 100% convinced they are one and the same. There is more variability in the old ones than in the ones available today, but it's all the same stone. Here are some of mine from recently, I've had a few other old Turkish too which I swapped for things.

The first stone in the top row I don't believe is actually a Turkish, though I've no idea what it is. The second was found in the US, and I believe is an old Pike stone, it's extremely fine. The third (black) one is probably the same level but it's a bit faster in use. The fourth is softer and faster, it was the first one I found and might still be my favourite. The fifth is pretty soft and coarse, though it was cut parallel to layers in the rock which gives it a kinda combi effect, with one side slightly finer than the other.

The four stones on the bottom row are all modern Cretans. The first stone is very dark, hard and fine, it's quite comparable to the black Turkish stone above. The other three are all quite similar just at various stages of oil soaking - partially soaked, fully soaked, and not soaked at all. In terms of speed and level they're probably around about the average point for old Turkish, ime.

Here's a pic of the 'combi' effect on the fifth Turkish:

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The reason I've found quite a lot of these stones is an interesting one. Until a few months ago I was living in Australia for a few years, and they're far more common to find there than basically anywhere else. I'll copy and paste below something I wrote about why that is...

 

[cotedupy]

[Copied from a post I made on KKF earlier this year]


For a while I, and a few others I've spoken to, have found it curious that in Australia old examples of Turkish Oilstones are relatively common - I come across them far more often than I do Washitas, a stone produced in much greater quantities, and which largely replaced the Turkish stone in many other countries. The penny dropped for me a month or so back when trying to research about the historic Mudgee Sharpening Stone from New South Wales.

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As far as I know the Mudgee stone was the only Australian whetstone ever quarried on a reasonably large commercial scale. The opening was announced with much fanfare, and a clearly significant commercial investment, in January 1890, and by March they had had to double the shifts worked in order to keep up with demand. Yet less than two years later production had ceased entirely, for want of custom.

To sustain a commercially viable whetstone business you need to be in a country with enough people who need whetstones, and when I say 'people' - that usually means 'industries'. In 19th century Britain, as well as having a far larger population than Australia you also had a sizeable cutlery industry, and even then much whetstone quarrying was still the by-product of quarrying for building stone. Earlier in the 18th and 19th centuries there had been quite significant production of scythestones, but the industry died out completely in a very short space of time after advances in the automation of agriculture during the industrial revolution. So what did the owners and investors of the Mudgee Sharpening Stone Company imagine was going to sustain them?

The answer obviously, was sheep. There are a lot of sheep in Australia; today over 100 million, second only to China, and more than four times as many as New Zealand - an island nation to the east of Tasmania notable for being populated almost exclusively by sheep. Lots of sheep means lots of wool, and lots of wool means lots of shears that needed sharpening. The Mudgee stone was marketed directly at shearers as an alternative to the expensive imported stones they had been using, and initially it clearly went rather well. But production had begun at exactly the wrong time. The rapid uptake of a sheep shearing machine, created by Frederick Wolseley in 1888, killed the Mudgee Sharpening Stone Company dead in much the same way that automated harvesting had done the British scythestone industry 80 years before:

'But by February 1892 the Mudgee Sharpening Stone Company had ceased production owing to slow demand and the accumulation of stock. Sadly, by September that year the directors of the company had abandoned the idea of reopening the works. It was the rapid acceptance of the shearing machines invented by Frederick Wolseley from 1888 into the big station woolsheds which sounded the death knell for the Mudgee stones.'

And the quite specific timeline of that event I think has an interesting impact on how relatively common Turkish stones are in Australia in comparison to Washitas. Below is the only picture I've been able to find of what the Mudgee stone actually looked like (it's a type of slate), and we can see that Turkish stones and Washitas were also favoured by shearers:

By the turn of the century commercial production of Washita stones in the US had probably already been established for at least 50 years. But it wasn't until 1889 that they eventually made it to the UK, here's a contemporary account of how it immediately rendered the Charnley stone obsolete:

'In the year 1889 the “Washita”. An imported stone, appeared on the English market, and was hailed with delight by all woodworkers , who straightway discarded their “Charnley Forests” for ever.'

We can I think assume that at that time the Washita would not have been shipped directly to Australia from the US. The pacific ocean is big, and considerably more ships were going the other way round. Washita stones were taken to Britain and often rebranded by companies there; A B Salmen for instance sold Pike Washitas under a label identical to the Pike one but with their own name and logo. Indeed when Pike Norton created a subsidiary company in the UK in the early 1930s a large part of the reason was to establish more direct trade with other markets, and in particular - Commonwealth countries.

So if the Washita stone only arrived in Australia in 1889 at the very earliest, then like the Mudgee stone, it coincided almost exactly with the introduction of automated shearing machines and the total bottoming-out of the main market demand for whetstones in Australia. A market that had until that point been overwhelmingly dominated by the old Turkish Oilstones which are, perhaps unsurprisingly, still common to find here.

 

[cotedupy]

Before the start of metal use, certain tools were made of stone and volcanic glass.

I didn’t know this until recently, but obsidian scalpels are actually still used for surgery today apparently. Which is quite cool!

https://edition.cnn.com/2015/04/02/health/surgery-scalpels-obsidian/index.html

 

[D_W]

Excellent collection of turkish and cretan. My cretan is listed as the light colored type or whatever it is of the less fine label, but it's black once oil is introduced.

I thought about buying one of the fine ones to compare to the turkish stone that I have (my turkish stone is irregularly shaped and made in a form fitting box, which someone in the US informed me was written to be typical before early industrialization - I guess it was easier to make the box than shape the stone).

The very early washitas that I've had often have irregular bottoms, cut in facets, but sometimes two instead of one flat face, and usually closer to being a square in cross section - nearly the same thickness as width.

I agree with what you say about the modern cretans - I've had two in total, bought one, sold it, and then bought another - they are inexpensive in europe, or at least were at the time, and you could get a huge one of something like 5-10kilos if you wanted.

The cutting characteristics between the pair that I've had and the turkish oilstone are almost indistinguishable other than that the new stones are a little aggressive until they're broken in. In my case, the lighter colored stone is very slightly more coarse than the old turkish, but the difference is probably like that of 6k waterstone vs. 8k waterstone at the very most. Maybe less. I'm not sure i could tell them apart if I closed my eyes and honed something on them.

It's too bad they aren't sold in larger amounts so that they could be shipped surface and sold on amazon reasonably here - they're a very useful stone thanks to what's overall a very favorable tradeoff in fineness / speed. I'd go so far as to say the coarser stone is functionally a lot like a washita. If I had unlimited space, I probably would've contacted the guy who sold them on an EU site (maybe still does?) and bought a bunch.

The somewhat interesting choice of sizes - like 2.75 x 7 or so? sold here for $55 about a decade ago.

 

[raffo]

I didn’t know this until recently, but obsidian scalpels are actually still used for surgery today apparently. Which is quite cool!

https://edition.cnn.com/2015/04/02/health/surgery-scalpels-obsidian/index.html

That's right, I had read that at some point too. Manufactured edges can't match the edge of obsidian. They're used to cut soft tissue, though. They're fragile.

 

[cotedupy]

Excellent collection of turkish and cretan. My cretan is listed as the light colored type or whatever it is of the less fine label, but it's black once oil is introduced.

I thought about buying one of the fine ones to compare to the turkish stone that I have (my turkish stone is irregularly shaped and made in a form fitting box, which someone in the US informed me was written to be typical before early industrialization - I guess it was easier to make the box than shape the stone).

The very early washitas that I've had often have irregular bottoms, cut in facets, but sometimes two instead of one flat face, and usually closer to being a square in cross section - nearly the same thickness as width.

I agree with what you say about the modern cretans - I've had two in total, bought one, sold it, and then bought another - they are inexpensive in europe, or at least were at the time, and you could get a huge one of something like 5-10kilos if you wanted.

The cutting characteristics between the pair that I've had and the turkish oilstone are almost indistinguishable other than that the new stones are a little aggressive until they're broken in. In my case, the lighter colored stone is very slightly more coarse than the old turkish, but the difference is probably like that of 6k waterstone vs. 8k waterstone at the very most. Maybe less. I'm not sure i could tell them apart if I closed my eyes and honed something on them.

It's too bad they aren't sold in larger amounts so that they could be shipped surface and sold on amazon reasonably here - they're a very useful stone thanks to what's overall a very favorable tradeoff in fineness / speed. I'd go so far as to say the coarser stone is functionally a lot like a washita. If I had unlimited space, I probably would've contacted the guy who sold them on an EU site (maybe still does?) and bought a bunch.

The somewhat interesting choice of sizes - like 2.75 x 7 or so? sold here for $55 about a decade ago.

To be completely honest I wouldn't fret too much about finding a darker, finer example. The faster, slightly coarser versions are better (imo) because as you say - they can start to almost have the kind of range as Washitas. Whereas fine ones are comparatively slow, and can't do the heavy lifting so well. You probably sharpen a wider variety of types of blade than I do, so might find more of a use for them, but for me - the very fine examples of Turkish/Cretan sit in a kind of grey area between being good for kitchen knife edges and being good for razor finishing.

All four of the Cretans in my pic there are the same size as the ones Griffiths used to have, and you're right - it's something like 170 x 70. I got them directly from the person in Greece who originally requested that size be cut, and I think sold them to GSG. Nice size for knives I think.

Would love to see a pic of your irregularly-shaped old one if you have...

 

[cotedupy]

There's a lot in "The Wood Age" by Roland Enos about early tools and the development from wood to wood and stone.

Cheers for this recommendation too, I'll have to hunt down a copy. As you can possibly tell - I have a slightly geeky interest in this kind of thing!

 

[essexalan]

To be completely honest I wouldn't fret too much about finding a darker, finer example. The faster, slightly coarser versions are better (imo) because as you say - they can start to almost have the kind of range as Washitas. Whereas fine ones are comparatively slow, and can't do the heavy lifting so well. You probably sharpen a wider variety of types of blade than I do, so might find more of a use for them, but for me - the very fine examples of Turkish/Cretan sit in a kind of grey area between being good for kitchen knife edges and being good for razor finishing.

All four of the Cretans in my pic there are the same size as the ones Griffiths used to have, and you're right - it's something like 170 x 70. I got them directly from the person in Greece who originally requested that size be cut, and I think sold them to GSG. Nice size for knives I think.

Would love to see a pic of your irregularly-shaped old one if you have...

I bought some Cretan stones directly from the shop some years ago and I asked for something roughly 8"x3"x1". A large brick turned up with several other sizes included. Types available were white, grey and black but they had no black stones in stock. Cost was very low at the time.
The large stone, light grey, was very friable in nature even after it was dressed with particles continually breaking loose. I then read that these stones were "cooked" in warm oil for several days so that the entire stone was infused with oil in my case walnut oil. Changed the colour and nature of the stone completely. I doubt that a Cretan hone treated in this fashion could ever be returned to it's natural state.
If you look closely some of these old hones have a distinct green or amber hue to them which would probably have been caused by the olive oil used.
Old timers in the UK call Washita stones Turkey stones just to add to the confusion.
Shipping from Crete now makes purchasing these stones prohibitive unless you know somebody stopping off on a cruise.

 

[cotedupy]

I bought some Cretan stones directly from the shop some years ago and I asked for something roughly 8"x3"x1". A large brick turned up with several other sizes included. Types available were white, grey and black but they had no black stones in stock. Cost was very low at the time.
The large stone, light grey, was very friable in nature even after it was dressed with particles continually breaking loose. I then read that these stones were "cooked" in warm oil for several days so that the entire stone was infused with oil in my case walnut oil. Changed the colour and nature of the stone completely. I doubt that a Cretan hone treated in this fashion could ever be returned to it's natural state.
If you look closely some of these old hones have a distinct green or amber hue to them which would probably have been caused by the olive oil used.
Old timers in the UK call Washita stones Turkey stones just to add to the confusion.
Shipping from Crete now makes purchasing these stones prohibitive unless you know somebody stopping off on a cruise.

Ah interesting that you got some stones when they were still selling the three different colours. In my pic above the one on the left I think is probably what would be called the 'black' kind, with the other three the normal 'grey' (I think). The 'white' version you have is noticeably softer and coarser then...? Sounds cool!

I've always wondered what exactly made the old stones different colours - whether it was the type of oil, or whether it was something in the stone. My suspicion is the latter though. I've had stones with some really funky colours in them; red, yellow, orange, pink that were definitely part of the stone itself. But it's possible that some types of oil could cause green / brown colours too as you say. Here's one not pictured above that I don't have any more which was very noticeably green:

The reason I think the colour may be more to do with the stone itself is that when I find old stones I tend to degrease them, and then re-soak in mineral oil. They actually degrease very quickly, far more quickly that Washitas for instance. The pic below is after about 30 mins in Simple Green; at this point it's still got some oil in the middle which would seep back to the surface, but if you leave them degreasing for a day or two you can get it all out. I think this was the black Turkish in middle of the top row above:

 

[cotedupy]

the olive oil used

It's certainly true as you say that old Turkish stones would normally have initially been soaked in olive oil. There are a couple of old sources that describe them being transported to Smyrna in barrels of it, and I found an old Levant Company duty document from 1836 which shows they were being imported into Britain by the 1000, 'in casks the one hundred'.

Though there must also have been some that arrived 'raw' I think, as there are also descriptions of them being boiled in milk before use. Which is another interesting example of geography being perhaps the largest influence on how stones were used / treated... Mediterranean countries generally do not have much of a history of milk production*, outside of individuals using goat or sheep's milk for cheesemaking. Whereas in Britain you have rather more cows than olive groves, so you make do with what you've got!

(I've never actually tried the milk thing, I wonder if it'd result in a different colour? I imagine it might...)



* The notable exception to this being the island of Menorca, which still has a significant dairy (and Gin) industry as legacy of British rule between 1708 - 1802. But hop over on a boat to Mallorca; you'll barely see a cow anywhere, and your liquor will be flavoured with the traditional 'Herbes' rather than Juniper.

 

[essexalan]

Ah interesting that you got some stones when they were still selling the three different colours. In my pic above the one on the left I think is probably what would be called the 'black' kind, with the other three the normal 'grey' (I think). The 'white' version you have is noticeably softer and coarser then...? Sounds cool!

I've always wondered what exactly made the old stones different colours - whether it was the type of oil, or whether it was something in the stone. My suspicion is the latter though. I've certainly had stones with some really funky colours in them; red, yellow, orange, pink that were definitely part of the stone itself. But it's possible that some types of oil could cause green / brown colours too as you say. Here's one not pictured above that I don't have any more which was very noticeably green:

View attachment 143766


The reason I think the colour may be more to do with the stone itself is that when I find old stones I tend to degrease them, and then re-soak in mineral mineral oil. They actually degrease very quickly, far more quickly that Washitas for instance. The pic below is after about 30 mins in Simple Green; at this point it's still got some oil in the middle which would seep back to the surface, but if you leave them degreasing for a day or two you can get it all out. I think this was the black Turkish in middle of the top row above:

View attachment 143767

The white Cretan was a bit like a soft white Arkansas in character. The grey Cretan changed colour completely to a dark olive green with the inclusions showing up lighter. Fine and slow cutting after treatment. The stones appear to be quite porous as a lot of bubbling went on during the oil soak and quite a lot of oil was soaked up, this was followed by several hours in a low oven. The oil appears to set hard in the stone which would help bind it together and make it difficult to clean unlike a Washita. I will have to dig the other stones out for a comparison.
Some years back and Charnley Forest stones were there for the taking when they cut the bypass through the outcrop. Most of them went in the road foundations.

 

[cotedupy]

The white Cretan was a bit like a soft white Arkansas in character. The grey Cretan changed colour completely to a dark olive green with the inclusions showing up lighter. Fine and slow cutting after treatment. The stones appear to be quite porous as a lot of bubbling went on during the oil soak and quite a lot of oil was soaked up, this was followed by several hours in a low oven. The oil appears to set hard in the stone which would help bind it together and make it difficult to clean unlike a Washita. I will have to dig the other stones out for a comparison.
Some years back and Charnley Forest stones were there for the taking when they cut the bypass through the outcrop. Most of them went in the road foundations.

Oh I've never tried putting one in an oven after soaking. Though I have heard you can melt wax into them in an oven, which makes them extremely fine and slow, and is apparently irreversible. Certainly though every old Turkish I've had degreased far easier / faster than Washitas generally do. Interesting too that your one went dark green - the grey Cretans that I've had all just went dark grey with mineral oil. You could well be right that the walnut oil played a part.

Would be cool to see yours if and when you do get them out!

 

[essexalan]

Oh I've never tried putting one in an oven after soaking. Though I have heard you can melt wax into them in an oven, which makes them extremely fine and slow, and is apparently irreversible. Certainly though every old Turkish I've had degreased far easier / faster than Washitas generally do. Interesting too that your one went dark green - the grey Cretans that I've had all just went dark grey with mineral oil. You could well be right that the walnut oil played a part.

Would be cool to see yours if and when you do get them out!

Have heard of "pickling" them in milk but never tried it, that might get a bit cheesy. I think the Cretans are more porous than Washita but would have to slice mine down the middle to see how far the oil treatment has penetrated.
LH stone is untouched Cretan Grey, middle stone is the brick after oil treatment and the RH stone is a Cretan Black. Cretan White has disappeared.
Green tint to the treated stone is apparent in sunlight but the semi hard walnut oil residue I cleaned off was still walnut oil colour.

 

[D_W]

Oh I've never tried putting one in an oven after soaking. Though I have heard you can melt wax into them in an oven, which makes them extremely fine and slow, and is apparently irreversible. Certainly though every old Turkish I've had degreased far easier / faster than Washitas generally do. Interesting too that your one went dark green - the grey Cretans that I've had all just went dark grey with mineral oil. You could well be right that the walnut oil played a part.

Would be cool to see yours if and when you do get them out!

you could dissolve paraffin based wax out of the stones with kerosene, mineral spirits, etc.

I've dissolved paraffin into mineral spirits and it's gone fairly quickly at room temperature (using it as a method to deliver wax into pencil barrels so that they don't warp with seasonal changes).

 

[D_W]

(I should've said a soak in kerosene. I'm sure there are other solvents a lot stronger than simple green that would dissolve oxidized oils and waxes, but I don't know what they are.

Xylene in the US is also an option, though it's extremely aromatic without being quite as flammable as naptha (or gasoline or toluene)....from recent experience. It can still be a fire hazard, though - and the aroma is strong enough that it's the kind you think you're still smelling when you're no longer smelling it.

I used it to thin floor finish and it is strong enough to break down even water based paint in a paint brush, though it takes a couple of days - probably not as strong as acetone. I'd imagine oil based or hydrocarbon waxes, it would break down quickly.