Norton 'Economy' Stone: feedback from manufacturer re: abrasive type

[Obsessed with Edges]

In another thread (linked below), there was some discussion/debate over what abrasive type is used in the Norton 'Economy' stone, currently sold at one or more home improvement centers & hardware stores. I had found a catalog description (linked in the other thread) stating that Norton spec'd it as aluminum oxide. Others in the discussion had stated it was actually Crystolon (silicon carbide). This prompted me to send an email to Norton (actually to Saint-Gobain Abrasives, Norton's current parent company and owner), to confirm which type it actually was. What transpired via that, is below. I'm posting it in this new thread, so as not to go further off-topic in the other thread.

http://www.bladeforums.com/forums/s...-KA-BAR-USMC-Short-Came-dull-cannot-get-Sharp

This has all piqued my curiosity. So, just to confirm (hopefully), I sent off an email to Saint-Gobain Abrasives (apparently the current owner of the Norton Abrasives brand) to ask them about it. If they actually respond, I'll post it here. (...)

David

Got some updates from Saint-Gobain, re: the Norton 'Economy' stone (product code 87933), which is listed in their product catalog as aluminum oxide.

Seems to have opened up a can-o-worms at their end, to some degree. I initially inquired as to what abrasive type was used (aluminum oxide, silicon carbide or other), and their first response was that it was Crystolon (silicon carbide).

I then inquired as to the differences between this stone and the other similarly-packaged and nearly identical 'High Quality' stone (87935) listed as Crystolon in their catalog, and pointed out the big difference in price ($6 vs $20+). I also asked, if they're both actually Crystolon, what accounts for the price difference(?). I also pointed out the description of the Economy stone being listed as aluminum oxide in the .pdf catalog (I sent them a link to it also). This latter point is what got things sort of stirred up at their end, and another of their people (tech rep) got involved in the discussion. At their end, they saw in their computer records that in spite of different product codes (87933 vs 87935), the two stones were listed as essentially identical (both Crystolon), but they still didn't know why the big difference in price.

A little more digging at their end, and they sent me another email noting that they'd figured out that the 'Economy' stone (87933) was, at some time in the past, actually aluminum oxide. They mentioned that they switched from aluminum oxide to Crystolon (which prompted me to ask when that occurred?). More digging, and they got back to me and said the switch from aluminum oxide to Crystolon, in the Economy Stone (87933), was made in 2008. On that point, they did offer some speculation that the pricing hasn't apparently changed along with the switch from the original aluminum oxide version to Crystolon, so the 'newer' versions of the Economy Stone in silicon carbide (Crystolon) were underpriced. They also noted that their catalog descriptions of these apparently hadn't been updated to reflect the change to Crystolon.

I also asked, how would one be able to know the difference between the two, if older and newer versions of the Economy stone were both marketed under the same product number (87933), but older versions might be aluminum oxide(?). I pointed out the apparent differences I saw in color, of the stones shown in their catalog (the 'Economy' stone appeared more grey, while the 'High Quality' 87935 stone listed as Crystolon appeared darker/black). They then told me that the alox version will always be either a lighter grey, or one of several other colors in the older versions (including a light grey, but specifically excluding black). BUT, they assured me, the Crystolon version will always be darker/nearly black in color.

So, to summarize, it seems the current version of the 'Norton Economy Tool & Knife Bench Stone', part number 87933, should be silicon carbide (Crystolon, by their own words). And, to differentiate between the current version and possible older aluminum oxide versions out there, the Crystolon versions will always be darker in color (nearly black). If all this is truly the case, it might be a good time to go shopping for one of these, in the event the 'Crystolon' pricing ever catches up with the current 'Economy' description.


David

 

[HeavyHanded]

In another thread (linked below), there was some discussion/debate over what abrasive type is used in the Norton 'Economy' stone, currently sold at one or more home improvement centers & hardware stores. I had found a catalog description (linked in the other thread) stating that Norton spec'd it as aluminum oxide. Others in the discussion had stated it was actually Crystolon (silicon carbide). This prompted me to send an email to Norton (actually to Saint-Gobain Abrasives, Norton's current parent company and owner), to confirm which type it actually was. What transpired via that, is below. I'm posting it in this new thread, so as not to go further off-topic in the other thread.

http://www.bladeforums.com/forums/s...-KA-BAR-USMC-Short-Came-dull-cannot-get-Sharp



Got some updates from Saint-Gobain, re: the Norton 'Economy' stone (product code 87933), which is listed in their product catalog as aluminum oxide.

Seems to have opened up a can-o-worms at their end, to some degree. I initially inquired as to what abrasive type was used (aluminum oxide, silicon carbide or other), and their first response was that it was Crystolon (silicon carbide).

I then inquired as to the differences between this stone and the other similarly-packaged and nearly identical 'High Quality' stone (87935) listed as Crystolon in their catalog, and pointed out the big difference in price ($6 vs $20+). I also asked, if they're both actually Crystolon, what accounts for the price difference(?). I also pointed out the description of the Economy stone being listed as aluminum oxide in the .pdf catalog (I sent them a link to it also). This latter point is what got things sort of stirred up at their end, and another of their people (tech rep) got involved in the discussion. At their end, they saw in their computer records that in spite of different product codes (87933 vs 87935), the two stones were listed as essentially identical (both Crystolon), but they still didn't know why the big difference in price.

A little more digging at their end, and they sent me another email noting that they'd figured out that the 'Economy' stone (87933) was, at some time in the past, actually aluminum oxide. They mentioned that they switched from aluminum oxide to Crystolon (which prompted me to ask when that occurred?). More digging, and they got back to me and said the switch from aluminum oxide to Crystolon, in the Economy Stone (87933), was made in 2008. On that point, they did offer some speculation that the pricing hasn't apparently changed along with the switch from the original aluminum oxide version to Crystolon, so the 'newer' versions of the Economy Stone in silicon carbide (Crystolon) were underpriced. They also noted that their catalog descriptions of these apparently hadn't been updated to reflect the change to Crystolon.

I also asked, how would one be able to know the difference between the two, if older and newer versions of the Economy stone were both marketed under the same product number (87933), but older versions might be aluminum oxide(?). I pointed out the apparent differences I saw in color, of the stones shown in their catalog (the 'Economy' stone appeared more grey, while the 'High Quality' 87935 stone listed as Crystolon appeared darker/black). They then told me that the alox version will always be either a lighter grey, or one of several other colors in the older versions (including a light grey, but specifically excluding black). BUT, they assured me, the Crystolon version will always be darker/nearly black in color.

So, to summarize, it seems the current version of the 'Norton Economy Tool & Knife Bench Stone', part number 87933, should be silicon carbide (Crystolon, by their own words). And, to differentiate between the current version and possible older aluminum oxide versions out there, the Crystolon versions will always be darker in color (nearly black). If all this is truly the case, it might be a good time to go shopping for one of these, in the event the 'Crystolon' pricing ever catches up with the current 'Economy' description.


David

Thanks for the update! Glad I didn't put in the disclaimer on my Econstone video, and glad my senses weren't playing tricks on me.

I have been taking a very close look at a bunch of the manufactured stones in my collection following the original thread and beginning to wonder all sorts of things. From looking at the authentic Crystalon stone and comparing it to the econo stone I can say 100% they are not the same thing, not even due to a lack of pre-oil. They both are silicon carbide, but the particle distribution and ratio of binders is nothing alike, this may be the reason why the econo stone can glaze over - higher concentration of binders and lower purity of silicon carbide. This accounts for the lighter shade of grey as well. I also compared the Crystalon to my India stone and an ACE hardware stone that looked a lot like silicon carbide. The India appears to have fewer binders overall and a much much higher level of particle and surface uniformity - just as the product literature claims. I also noticed that the coarse side of my India stone grinds faster than the Econo stone, or ACE SiC stone - so to state the obvious - particle purity, percentage of binders, quality of firing process, all contribute to how well a stone performs. Cannot make assumptions based on abrasive type alone.

Glad you took the time to ask, and they took the time to respond. Now I can stop looking at my Econo stone sideways...

I'd like to put together some micrographs of these stones, but cannot get the camera to show the contrast I can see through the eyepieces. Will monkey around with the lighting and see if I can get something worth sharing.

 

[Obsessed with Edges]

Thanks for the update! Glad I didn't put in the disclaimer on my Econstone video, and glad my senses weren't playing tricks on me.

I have been taking a very close look at a bunch of the manufactured stones in my collection following the original thread and beginning to wonder all sorts of things. From looking at the authentic Crystalon stone and comparing it to the econo stone I can say 100% they are not the same thing, not even due to a lack of pre-oil. They both are silicon carbide, but the particle distribution and ratio of binders is nothing alike, this may be the reason why the econo stone can glaze over - higher concentration of binders and lower purity of silicon carbide. This accounts for the lighter shade of grey as well. I also compared the Crystalon to my India stone and an ACE hardware stone that looked a lot like silicon carbide. The India appears to have fewer binders overall and a much much higher level of particle and surface uniformity - just as the product literature claims. I also noticed that the coarse side of my India stone grinds faster than the Econo stone, or ACE SiC stone - so to state the obvious - particle purity, percentage of binders, quality of firing process, all contribute to how well a stone performs. Cannot make assumptions based on abrasive type alone.

Glad you took the time to ask, and they took the time to respond. Now I can stop looking at my Econo stone sideways...

I'd like to put together some micrographs of these stones, but cannot get the camera to show the contrast I can see through the eyepieces. Will monkey around with the lighting and see if I can get something worth sharing.

Agreed. When they told me the cheaper stone was also Crystolon, I immediately started thinking, there must be something different about the binders and/or concentration or purity of the abrasive itself, even if it's the same abrasive type. Makes no sense, otherwise. I'm sort of hoping they might get back to me again; once they started looking into it, they just kept firing more updates back to me, as they found them. I haven't asked them for more yet; I was actually surprised they stayed patient with all of my questions thus far. They do seem very willing to help, though. That says good things about their company, I think. :thumbup:


David

 

[HikingMano]

Thanks for the info :thumbup: I remember running into this issue in the past.

 

[David Martin]

Glad you got a response from these guys. I've e-mailed them on items in the past and gotten nothing. It's a big company and e-mails get lost in the shuffle. Still, I'm glad you two stayed on this matter to arrive at a definative answer from different ends of the equation. Well done gentlemen. DM

 

[David Martin]

So, the Economy stones are less pure with lower quality binders than Norton's higher quality retail stones. i.e. their standard IB-8. You must mean 'on the Economy stones' the SiC will be darker almost black. Because, their JUM-3 is not this color. Thanks, DM

 

[fervens]

I really appreciated the update and am glad they got back to you on this matter. I have had the same issue as DM trying to get ahold of them, so I'm surprised they did. But it also makes me feel better about the info they are giving you. Thanks again!

 

[Chris "Anagarika"]

It is always good to clear the mud (no pun intended).

Thanks for sharing, although no store around me sells this, the info is useful nonetheless.

 

[Obsessed with Edges]

So, the Economy stones are less pure with lower quality binders than Norton's higher quality retail stones. i.e. their standard IB-8. You must mean 'on the Economy stones' the SiC will be darker almost black. Because, their JUM-3 is not this color. Thanks, DM

The color variations are probably due to the binders themselves, as opposed to the SiC abrasive.

In their own words, from one of their emails to me (I added the bold highlight):

"Hi David, one thing I just thought about…. I told you earlier about some color differences….there was a time that some of our India stones were made from a light gray type of aluminum oxide (nowadays it’s brown…same abrasive, just colored differently now). So some of the older ones were indeed a lighter gray (probably the lighter ones in the picture on that webpage). But when comparing the gray india stones to crystolon, the crystolon will always be much darker, because the mineral it comes from is naturally black in color."

David

 

[HeavyHanded]

The color variations are probably due to the binders themselves, as opposed to the SiC abrasive.

In their own words, from one of their emails to me (I added the bold highlight):




David

As mentioned, the Econo stone has a lot of what appear to be binders - honestly I wouldn't be surprised to hear there was AlumOx mixed in as well, but is likely some form of quartz. I did some reading on SiC production and unless I misunderstood, every run of SIC will include material with a range of purities based on their location in the finished slug. I imagine there are some creative uses for the low-grade materials, such as the economy stone. I have an older grey stone from Vermont American that was also described as AlumOx and visually the grains appear very much like a washed out version of my India stone, but with a much wider range of particle size and with some of the same bits of pale green and dark blue glass/minerals/binder? that I see in the confirmed silicon carbide stones (including genuine Crystalon). It gets difficult to tell for sure what the composition is when there are so many impurities and I can only go by overall shape and color of the abrasives - this one might be SiC as well. Also - natural AlumOx might look very much like low purity silicon carbide, and some of the binders and unreacted silicon dioxide might look very much like natural AlumOx. One thing for sure, the better (and more expensive) stones seem to have fewer binders/unreacted silicates and much tighter tolerances for particle size. My ACE stone is a deep, rich color and looks like relatively good quality SIC under the microscope, but with a wider range of particle sizes per side and the overall appearance looks like there is something very different in the way the block is fired compared to the genuine Crystalon, I suspect a higher ratio of binders but maybe something even more fundamental. This stone was only 8.99. Was right next to a very light grey one of the same dimensions that was only 6 bucks for what I assume was low-grade AlumOx. There are deals to be had out there if your demands aren't too great, but it looks to me like you get what you pay for...

 

[David Martin]

HH, Thanks. So, even the Norton hecho in Mexico stones express tight grain binders and high concentration of material SiC or AlumOx. DM

 

[HeavyHanded]

HH, Thanks. So, even the Norton hecho in Mexico stones express tight grain binders and high concentration of material SiC or AlumOx. DM

My US made SIC puck looks identical to the Mexican Crystalon, but on older slipstone I have circa 80s I think, looks a bit different from either.

I just bought an older 8" India stone made in USA and am comparing it to my Mexican mfg. So far the only obvious difference is the US made one has a much more uniform coloration out of the box. Another difference that I created, the Mexican one has been boiled, I'm leaving the US one as is. As a result of boiling I can see voids going down into the stone, some of which look to be collecting some garbage. The US made one looks like a much more solid mass, but I believe this is the pre-oil filling in the voids. I recall one forumite who used chemical degreaser saying the stone produced a waxy goo that came out with repeated treatments. The pre-oiled stone needs considerably less oil to use and wipes absolutely clean. I believe this waxy goo is a more solid form of mineral oil (so perhaps very much like paraffin) and will slowly dissolve in whatever surface oil is used, especially the Norton brand which is a thin mineral oil. More to follow maybe - I have to do some grinding on the US made India to break it in more before any other differences show up, but so far the Mexican mfg seems to be faithful copy.
HH

 

[David Martin]

HH, Thanks for this information. So, your saying the early Norton, USA made stone and those later made in Mexico stones are close in appearance, or not? I got one of the made in Mexico stones and upon recieving it felt the need to boil it as it was loaded with something along the lines of heavy mineral oil or vasoline. Once, this was cleaned out the pores of the stone opened and it 'felt' much more gritty. Should you get one like this a pre-oiled/ pre-loaded stone. I recommend you thoroughly clean this out as it will load up with use anyway, when using mineral oil during sharpening. Yet, you know where you started and it may take some time before it loads up on you. Then clean it out again as normal maintenance of sharpening equipment. I use paint thinner and a wire brush to clean my stone after each use but have noticed 'Break-Free' does a better job. DM

 

[HeavyHanded]

HH, Thanks for this information. So, your saying the early Norton, USA made stone and those later made in Mexico stones are close in appearance, or not? I got one of the made in Mexico stones and upon recieving it felt the need to boil it as it was loaded with something along the lines of heavy mineral oil or vasoline. Once, this was cleaned out the pores of the stone opened and it 'felt' much more gritty. Should you get one like this a pre-oiled/ pre-loaded stone. I recommend you thoroughly clean this out as it will load up with use anyway, when using mineral oil during sharpening. Yet, you know where you started and it may take some time before it loads up on you. Then clean it out again as normal maintenance of sharpening equipment. I use paint thinner and a wire brush to clean my stone after each use but have noticed 'Break-Free' does a better job. DM

Here's what I'm seeing from the stones I own:

Recent USA mfg Crystalon puck and recent Mexico mfg Crystalon combination stone look identical. Its possible the puck was made in Mexico and the packaging didn't reflect the change. The material shows a fairly high level of uniformity as far as particle size and amount of binder. The combination stone has been boiled, the puck has not, but also did not claim to be pre-oiled. So far the puck shows no sign of loading up and has been used dry, with a splash of water, and with oil.
I have an older slipstone of 80s vintage that appears somewhat different than the two more recent mfg but haven't figured out what the difference is yet - might be as simple as the methods used to grind the SIC to the desired size or there could be a change in the binders.

Ace hardware silicon carbide stone shows many similarities to the Crystalon but with a wider range of particle size and a bit more binder. It also appears to be fired somewhat differently but might just need to lapped prior to use - some of what I'm seeing might be surface issues from the firing or post firing surface treatment. I have heard of some people having issues with Crystalon stones feeling somewhat glazed over as they come from the box - a quick lapping is said to deal very well with this. I haven't had any such issues, but will be lapping the ACE stone to see if this helps.

Norton economy stone appears to have even more range of particle sizes and even more binder or low purity silicon carbide. I have personally had this stone glaze over when lapped with another stone, but not if lapped with a loose grit. In use it performs very much like a Crystalon stone but maybe a bit slower - maybe a lot slower - I haven't done any side-by-side testing. It 'feels' the same and creates a very Crystalon-like mud when used with oil.

All the SIC stones have very small pale green and dark blue pieces of mineral/glass? that might be part of the binder or might be unreacted silicates. I initially suspected they're part of the binder but then that means very different manufacturers are all using the same binder materials - very possible and just as likely they're using the same 'seed' silicates during the manufacturing process but I really have no idea. These bits are not apparent in the India stone. I have an older Vermont American stone that claimed to be AlumOx and has similar colored bits in the fine side, but not the coarse side. The abrasive particles maybe aren't of high enough purity for me to tell what the abrasive is and as I speculate, natural ALumOx and low purity SIC might not only look very similar but might grind very similarly as well. The particles are more similar to the India stone but the binder and firing process must be very different.

My Mexican mfg India stone appears to have a less surface uniformity as far as coloration goes abrasive particle composition and distribution, binders, etc appear same as US mfg. I do not know what produces the classic "India stone" color. I have to admit I cannot readily make out the binders in the India stone, but have not taken good long looks yet and under varying lighting. I have boiled this one, but from what I can tell aside from the absence of the wax/lube/grease? and blotchy coloration, it seems to be a very close copy of the original American mfg stone. I have used the American mfg one to do some back-bevel grinding mostly just to break it in. It seems to wipe clean far more completely than the boiled Mexican India stone that I sometimes scrub down with soap and water and a stiff brush to clean up completely. I am going to leave the lube in the US mfg one and see how it works out over time. I suspect it will stay considerably cleaner than the boiled one when used with mineral oil. I would recommend at this point people not boil their Norton stone until they've tried them with some oil first - if that isn't agreeable go ahead and boil. I noted earlier, Norton and many other mfgs make and sell honing oil, none offer soapy water or any other fluids. Not saying other options might not work well, just pointing out the obvious.

Not sure if I'll bother to look any more into this, but have learned something from what I've already done - might be enough. People have been known to get bit nutty from spending too much time over a microscope...

 

[David Martin]

"It seems to wipe clean far more completely than the boiled Mexican India stone" I wish to take off at this topic. This same characteristic I've noticed with my Norton India stones as well. The Mexican made India stone which I boiled is harder to clean after sharpening than my older mid-80's, USA mfg. India stone. The USA stone gets very clean with one cleaning using paint thinner and a wire brush (2min. effort) and this one looks and feels to have never been pre-oiled. Whereas the Mexican made stone was and I tried to remove it. It will get clean but requires several 2min. attempts, perhaps 3.? This reason, I honestly don't know why. Plus, the USA mfg. stone works a little faster than the Mexican mfg. stone. Higher quality grit or binders between the stones.? DM

 

[Obsessed with Edges]

Just wanted to pass along some observations, re: the 'new' Norton Economy Stone.

I picked one of these up at Home Depot this week, and noticed the stone is labelled as 'MADE IN BRAZIL'. Something sort of odd I noticed, I did see at least one in the store display, on which the packaging indicated Mexico as country of origin, but the stone under the shrink-wrap was still marked as 'MADE IN BRAZIL'. The one I picked up doesn't indicate Mexico on either the packaging or on the stone.

At any rate, I've also noticed this stone doesn't appear to be pre-oiled, as with some older stones described from others posting here. I dribbled a few drops of mineral oil on it, and the stone drinks it up like water (never seen a stone soak up the mineral oil this fast). It soaks up water like a sponge too, as I found when giving it a soap/water bath, and takes a pretty long while to dry afterwards (a day or so).

The stone had some relatively sloppy-looking finish issues on the Coarse side; what appeared to be a ~1/4" diameter dried/hardened gob of black stuff at one end. Almost looks like the tell-tale 'button' of stuff left on injection-molded products, which seems odd on this stone. Maybe binder material, I'm not sure. Also some whitish flecks of relatively hard material scattered across the coarse side. Most were proud of the surface (as was the black stuff mentioned), so I just rubbed the coarse side with a cheap Arkansas stone to make everything flush (also did a nice job cleaning/lapping the Arkansas stone).

Haven't done anything major with the stone yet, other than a little re-bevelling of a cheap stainless paring knife I use frequently, to get a feel for the abrasive. Did this all on the 'Fine' side, which still worked quite aggressively on this particular blade. Still pondering which of my knives will get a new bevel during the break-in of this one...


David

 

[David Martin]

Dave, Thanks for the preliminary run down. Looking forward to your subsequent assessments and further experiences in using this stone. Haa, as I have a bonus points card in my pocket for 10$off at my local Ace Hardware store and may use it for one of these stones. DM

 

[HeavyHanded]

Just wanted to pass along some observations, re: the 'new' Norton Economy Stone.

I picked one of these up at Home Depot this week, and noticed the stone is labelled as 'MADE IN BRAZIL'. Something sort of odd I noticed, I did see at least one in the store display, on which the packaging indicated Mexico as country of origin, but the stone under the shrink-wrap was still marked as 'MADE IN BRAZIL'. The one I picked up doesn't indicate Mexico on either the packaging or on the stone.

At any rate, I've also noticed this stone doesn't appear to be pre-oiled, as with some older stones described from others posting here. I dribbled a few drops of mineral oil on it, and the stone drinks it up like water (never seen a stone soak up the mineral oil this fast). It soaks up water like a sponge too, as I found when giving it a soap/water bath, and takes a pretty long while to dry afterwards (a day or so).

The stone had some relatively sloppy-looking finish issues on the Coarse side; what appeared to be a ~1/4" diameter dried/hardened gob of black stuff at one end. Almost looks like the tell-tale 'button' of stuff left on injection-molded products, which seems odd on this stone. Maybe binder material, I'm not sure. Also some whitish flecks of relatively hard material scattered across the coarse side. Most were proud of the surface (as was the black stuff mentioned), so I just rubbed the coarse side with a cheap Arkansas stone to make everything flush (also did a nice job cleaning/lapping the Arkansas stone).

Haven't done anything major with the stone yet, other than a little re-bevelling of a cheap stainless paring knife I use frequently, to get a feel for the abrasive. Did this all on the 'Fine' side, which still worked quite aggressively on this particular blade. Still pondering which of my knives will get a new bevel during the break-in of this one...


David

This compares well with what I found, including the product/pkg discrepancy. Mine had a lengthwise curl as if the fine side had contracted more than the coarse side when fired. Had to lap it vigorously with a tile rubbing stone and some loose 120 grit SiC. I also put it in a small dish made from foil and soaked it in mineral oil - it comes around pretty quick.

 

[Obsessed with Edges]

This compares well with what I found, including the product/pkg discrepancy. Mine had a lengthwise curl as if the fine side had contracted more than the coarse side when fired. Had to lap it vigorously with a tile rubbing stone and some loose 120 grit SiC. I also put it in a small dish made from foil and soaked it in mineral oil - it comes around pretty quick.

I'm still debating whether to oil it at all, which is why I haven't yet tackled a major project with it. Thinking about wetting it by other means, like dish soap + water, or Simple Green + water (I've read it's popular too; picked up a bottle of it at HD along with the stone). As readily as it soaked up moisture, the idea of using it just like a waterstone did cross my mind.

I've noticed some of that 'contraction' you saw in yours, also bending/curling towards the Fine side of the stone. When checked with a straight edge, the contraction appears to be in both axes (lengthwise and across it's width). I'm wishing now that I'd also picked up one of the tile-rubbing stones while I was at HD. I actually thought about that when I was in the store, but didn't pick one up.


David

 

[HeavyHanded]

I'm still debating whether to oil it at all, which is why I haven't yet tackled a major project with it. Thinking about wetting it by other means, like dish soap + water, or Simple Green + water (I've read it's popular too; picked up a bottle of it at HD along with the stone). As readily as it soaked up moisture, the idea of using it just like a waterstone did cross my mind.

I've noticed some of that 'contraction' you saw in yours, also bending/curling towards the Fine side of the stone. When checked with a straight edge, the contraction appears to be in both axes (lengthwise and across it's width). I'm wishing now that I'd also picked up one of the tile-rubbing stones while I was at HD. I actually thought about that when I was in the store, but didn't pick one up.


David

The rubbing stones make a good base and they're pretty flat as well, but for serious lapping I've found failure to include a loose grit to result in some stone glazing, no matter how much water is used. Even a pinch or two of blasting grit will work wonders compared to the bare stone. Have heard the Simple Green works well too, and I used to use soapy water, but after trying oil for a while, I can't bring myself to use another method unless I have no choice. Other options work, or nothing at all if I'm camping or on the go or in a real hurry. The oil seems to keep the stone in the best shape and in my hands the best edge per grit value. Have heard the oil promotes breakdown of the binder faster than other choices, don't know if this is true but my stones all look brand new after much use - actually better than brand new. Keep your observations coming, I'm very interested.

HH