The Fresh Loaf

A Community of Amateur Bakers and Artisan Bread Enthusiasts.

Flour Mill/Grind Stones - Real Stone vs Ceramic Corundum / Carborundum (i.e. Sandpaper)? is Abrasive in our food SAFE?

Nick Sorenson's picture
Nick Sorenson

Flour Mill/Grind Stones - Real Stone vs Ceramic Corundum / Carborundum (i.e. Sandpaper)? is Abrasive in our food SAFE?

I'm very much into wood working which involves some hand tool sharpening. In the sharpening world, we're very familiar with abrasives. Some people use sandpaper taped to a piece of plate glass or a flat granite tile working from course (say 400) to fine (say P2000 wet). Other people use a wet stone which is basically a block of adhesived together Aluminum Oxide (the main ingredient/abrasive in most sandpapers). Others (including me) prefer natural stones to sharpen with. I like them because they're VERY hard and don't wear out. The other methods use grit particles which wear away in a slurry of tool steel and abrasive particles/binder as the tool is sharpened. It's not a big deal because you wash the stone off when you're done.

That background given, I don't like the idea most grind stones are using when it comes to flour mills. I don't think most bakers think about it like I just did. But having used abrasives as much as I have (especially with stones and grinders) I don't like the idea of all that abrasive and binder going into my food/flour. I've also heard that dentists don't like the abrasive either (read that it can effect tooth enamel). Not to mention eating aluminum... I know... I know... they say it won't hurt but still... it's aluminum! Most home flour mill grinder manufacturers call it Ceramic Corundum but from what I've read (including the Wikipedia on "Corundum"), that's just another name for Aluminum Oxide. I've seen this in several places so I assume this to be the case. It makes sense, most stones for grinders (bench grinders for instance) are made using Aluminum Oxide as the abrasive.

But long and short of it, does this bother anybody else? I personally don't like the idea. I'd really like to find a real stone grinder if there is such a thing. Maybe it's not a big deal regarding our health but I'm curious.

The stones I use for sharpening tools (and my food knives) are Arkansas Oil Stones made by Hall's Pro Edge. I really have been happy with them. I use diamond for the course roughing out and switch to a black oil stone for the final edge. Works great! That's unrelated but part of what got me thinking about the stones in grinders.

Nickisafoodie's picture
Nickisafoodie

Try a wonder mill or similar high speed impact mill, cost about $250.  They work great, keep the flour cool, and even a medium setting makes fine flour.  No sharpening or other maintainence needed, and faster thruput too...  Been using one for 15 years regularly and it is still going strong.  use the search box in upper left corner and you will see lots of postings on mills... 

Good luck

varda's picture
varda

I just did a google search and this old TFL post popped up:  http://www.thefreshloaf.com/node/14546/wolfgangkomo-mill-stone-safety

suave's picture
suave

You have to understand the difference between ceramic and abrasive. 

pmccool's picture
pmccool

Of course, then you'd have the concern of microscopic metal particles in your food...

Not to put too fine a point on it, but everything we eat has something in it that is harmful to our bodies, if we eat too much of it.  That last phrase is the kicker.  If our water supply has high levels of naturally occurring arsenic in it, that's not a good thing even though it is 100% natural. 

Natural stones in mills are just as prone to wearing as man-made stones, which is why they often need to be re-dressed after extended use.  Where do the worn parts go?  Into your flour and then into your body.  They will wear your teeth as much as the carborundum particles, which is to say not much.  This was a big deal in many communities hundreds of years ago if the local mill used stones that tended to wear rapidly, or if the miller was not managing the mill properly.  In such cases, the flour contained high levels of grit from the stones and peoples' teeth suffered greatly from wear.  Nowadays, with most of our flour produced by steel roller mills, it's a non-issue.

So, continue your studying, figure out what sounds scary (but isn't) and what truly is scary, and make your choice accordingly.  My opinion is that any of the choices mentioned so far will produce good flour with minimal risk to you, the user.  You may come to a different opinion.  Either way, enjoy your freshly ground whole-grain flour.

Paul

Nick Sorenson's picture
Nick Sorenson

Hi Paul,

You mention that natural stones will wear just as much as synthetics, I don't mean to argue for the sake of argument of course and I agree with a lot of what you said especially the part about everything has something harmful the key is not to eat too much of it. The solution to polution is dilution.

But back to natural vs synthetics... this is with sharpening stones as a basis (don't know if it applies 100% to mill stones but I certainly would think that it should), but natural stones stay perfectly flat basically for the life of the stone where-as the water stones (synthetics using alum ox) have to be dressed/re-trued to flat regularly. The reason for this being, as mentioned in the original post, there's always a slury of aluminum oxide and binder/adhesive that's worked loose from the stone during sharpening. With a natural oil stone, there's basically (for all intents and purposes) ONLY the metal from the edge that was sharpened and that's it. 

So the two do wear quite differently and with natural stone wearing hardly at all. You definitely don't see the particulate like you do with the synthetic stones. And if you've sharpened tools or knives with a wetstone, you know that it's quite a bit that breaks loose. So it's quantity of particulate/foreign matter that I think would be the biggest difference besides the safety of the material itself.

pmccool's picture
pmccool

One base assumption you have mentioned is that milling produces the same slurry on the surface of the stone as occurs during tool sharpening.  That does not happen during milling.  If it did, no one would use a man-made material for a millstone because the inclusion of abrasive material in the flour would be intolerable.  

Grains, even harder types such as durum wheat, are significantly softer than metal.  Consequently, they do not wear the burrs as much as does a metal tool.  It is absolutely true that wear occurs.  However, the amount of wear from one mill run to the next wouldn't be visible to the unaided eye, whereas tool sharpening produces visible wear during each use.  From what I have been able to find on-line (it's a bit dubious since most of the sites are by manufacturers or their resellers), the corundum-ceramic stones are advertised as having about a 15 year life and granite stones are advertised as having about a 20 year life.  That also points to a low rate of wear for the synthetic stones and a correspondingly low deposition of the stone material in the flour.

Please understand that I'm not trying to steer you toward a material that you are uncomfortable to use.  Just be sure that you don't extrapolate the outcome from one type of use (tool sharpening) to the outcome of a very different (grain milling) use.  And be sure to discern whether the material used for sharpening blades is the same as, or different than, the material used in millstones.  Even if the abrasive material (carborundum, corundum, or other) is the same in both uses, I suspect that the substrate or matrix in which the material is housed is very different and therefore leads to a different outcome.

Paul

Nick Sorenson's picture
Nick Sorenson

This makes complete sense. I am used to a HUGE mess with waterstones and edge tools/knives and much less mess with the natural arkansas oil stones. So I just pictured the wetstone (synthetic) mess carrying over to grinding wheat. I suppose it's probably to a much lesser degree with wheat. Didn't think about that point. Thanks for mentioning it. If I had the choice between a rock with it's God given bond vs a bunch of abrasive particles held together by glue, I'd pick the rock's natural adhesion any day. But for the most part, it looks like all home level grinders that use a "stone" pretty much have a man made abrasive as far as I can see. BUT... maybe it's not that big of a deal when grinding this soft of a medium (wheat).

MangoChutney's picture
MangoChutney

No, this does not bother me.  I am not keen on eating any kind of grit in my food, but whatever may be coming from the synthetic burrs in my Wolfgang mill is apparently too fine to bother me if it even exists.  Sharpening metal tools and grinding grain are not the same.  Corundum is much harder than grain and the plates are not supposed to be allowed to touch so they don't grind each other.  I have seen a fine dark powder resulting from running the mill with the plates adjusted too close together.  This does not seem to appear when the plates are properly adjusted, nor when grain is added with properly adjusted plates.

I use my Wolfgang mill daily for making breakfast, every five days to make bread, and occasionally otherwise.  Breakfast is 1/3 cup oat groats milled with 1 tablespoon flax seeds, which does not clog my mill as long as I mix the two well.  I have even begun lately to mill the combination on my finest setting, which I had previously avoided because even oats alone has more fat content than other cereal grains.  Flax alone even at a coarse setting will indeed clog the mill.  However, it is easily cleaned if this should happen.  The worst part is cleaning up the flax seeds from the counter top when you turn the mill upside down to dump them out.

As for whether alumina is toxic, I don't believe that it is.  Differing oxidation states of metals behave very differently, as do differing salts.  As an example, you eat sodium chloride and in fact must have some of it in your diet.  Sodium bicarbonate is baking soda.  Sodium carbonate is washing soda, and can be used to coat pretzels and bagels.  Sodium hydroxide is used to clean out drains, and for the previously mentioned coatings if you are brave.  Sodium metal reacts with water to form hydrogen which can easily explode due to the heat created by the reaction.  Alumina is a fairly innocuous salt of aluminum.

sonika's picture
sonika

Maybe you should consider the Samap hand grain mill. Here is the link for you guys to look at:

http://www.youtube.com/watch?v=Ukc_BLolCHk

I found it while doing research in order to decide what kind of mill to get (still undecided). If anyone has prior experience with it, please enlighten us on the stone wear. I,  too, am concerned about the unwanted materials that end up in the flour as a result of milling parts wear. In case anyone is interested, I have opened a topic about the subject here:

http://www.thefreshloaf.com/node/36017/grain-mill-abrasion-measurement-experiment


jjcobbie3's picture
jjcobbie3

I know this is a very old thread, but I will weigh in as I've used my Komo mill for about 5 years now.  I recently decided to discontinue use of the Komo Fidibus XL due to this very issue.

After inspection of my Komo corundum ceramic stones, large pieces of the corundum are missing , resulting in a sort of furrowing occurring, especially near the center where the grain enters the milling chamber.  Very noticeable stone loss, and I have also had noticeable grit in my breads.  Although I wouldn't describe this crunching as frequent, I would describe it as normal, and noticed the phenomenon regularly with consistent use over the 5 years.  Given that the corundum is bound together with some sort of adhesive, this does raise a red flag to me, and deserves further scrutiny as to what the adhesive is made of.

In my search for a natural alternative, I found the Salzburger Getreidemuhlen mills.  Some of their mills use a natural granite millstone, while others have the corundum ceramic grinding wheels.  I ordered the MT18, which is their largest mill, primarily because it uses natural granite millstones, and also has a larger millstone diameter.  I have been extremely happy with the resulting fineness of the flour, and have thus far had no issues of grittiness in my breads.  Also, the milling chamber is not made of plastic, which reduces the static charge on the flour.  My Komo made flour always would cling to my stainless steel bowls due to the charge created in the milling chamber.

As for the Salzburger, it is an excellent machine, and worth the steep price tag for both piece of mind (i.e. no binders or grit in my food), and for the flour fineness capability.  I still like to freeze my grains prior to grinding to reduce the flour output temperature.  I generally will grind a 10 lbs batch of flour each time and freeze the resulting flour to prevent oxidation.  What I have found is that at an extremely fine setting, the mill will shut off approximately 4 lbs into milling due to an automatic trip in the motor that prevents overheating.  Although this has been a bit of an annoyance, I have been able to work around it fairly easily by allowing the mill time to cool, and finishing processing.  This takes generally less than an hour.  This mild inconvenience is far outweighed by the quality of the flour produced, and I do believe that the "God-made" bond inherent in the natural granite millstone outperforms the corundum ceramic stones quite easily, and logically.

Lastly, the adjustment process for the mill is quite nice with infinitely variable adjustment due to the stainless steel thread design with set screw style stop.  I have found that as the mill heats up, there must be a slight expansion of the stones; therefore, once the flour output slows I loosen the mill up slightly until the equilibrium is reached.  I check the fineness of the flour by rubbing it between my finger and thumb, and once I am satisfied the mill can be left to grind without much attention.

I hope this helps someone.  I am not paid nor do I receive any sort of compensation from Salzburger Mills, but I will say, I'm extremely impressed with their mills over their competitors.

https://natural-grainmills.com/salzburger-commercial-grain-mills/

David R's picture
David R

I don't think this shows natural stone being better, so much as it shows this particular manufactured stone being worse. Notice that you (and maybe they) haven't compared with other types of manufactured stones.

Maybe there aren't any other kinds of manufactured stones in existence. But I kind of doubt that.

jjcobbie3's picture
jjcobbie3

I think it is pretty straightforward that the natural stones use no adhesive, whereas the corundum ceramic stones require adhesive to be manufactured.  That's a pretty stark difference, in my opinion.

In addition, you can look to what professional millers use for grinding grain as an example.  There are many granite stone mills used in commercial production of flour, but to my knowledge, not a single large scale corundum ceramic mill in use commercially producing flour.  If the corundum ceramic material were superior in any way, it would be logical to find large corundum ceramic mills to exist commercially.

David R's picture
David R

Are you really insisting that "corundum ceramic" from one particular manufacturer is the only synthetic stone in the world?

jjcobbie3's picture
jjcobbie3

I haven't said anything about "synthetic stone" manufacturing, I'm merely pointing out that all "synthetic stones" require some sort of adhesive as a bonding agent, whereas natural stones do not require it.  I'm sure someone could make a mill stone using natural crushed granite, and adhesive, but the adhesive would seem to be inherently weaker than the granite in it's original form as a solid rock, and it would then subject the grains to coming in contact with the adhesive - which would defeat the purpose.

I don't doubt that there are probably some better "corundum ceramic stones" manufactured that may not have the same issues that my Komo "corundum ceramic stones" have had, but to me that is a mute point; there are true/natural granite stone mills on the market that remove the adhesive from the equation entirely, and do a very nice job milling flour.

Clearly you are entitled to your opinion, and to support corundum ceramic stones as a fine option, but I am also entitled to my opinion, and I am extremely satisfied with the larger granite mill stones of the MT 18 mill made by Salzburger.  I believe the flour the granite millstones produce is of superior quality to what I was getting from my Komo mill.  Although I haven't experienced any other mills besides the Salzburger and the Komo Fidibus XL, my assertion is that the Salzburger takes the cake (or the bread), hands down.

David R's picture
David R

I mean to say that all we know so far is that one type of synthetic ("corundum ceramic"), from one single manufacturer, is clearly inferior. What about other formulas? What about other manufacturers?

I can find you mountains (literally) of 100% natural stone that makes far worse millstones than the corundum ceramic you're discussing. That's because I'm choosing a poor example of natural stone. I'm saying it's possible that you're choosing a poor example of synthetic stone - maybe there are better ones.

jjcobbie3's picture
jjcobbie3

I suppose a person could get the Salzburger MT5 mill, which has the synthetic "corundum ceramic stones" if they prefer an artificial stone for some reason, and it is possible that the Salzburger sourced "corundum ceramic stones" are superior to the Komo; although I have not been privileged to try the MT 5 mill.

We're really just talking natural, vs synthetic in this debate, and my preference is the natural granite stones.  Yes, there are other natural stones that are not suitable for a grain mill, such as limestone, or even some types of granite.  But the type used in the MT 18 mill is very suitable, and very capable.

https://natural-grainmills.com/natural-stone-by-flour-mills/

David R's picture
David R

Of course we're really just talking natural vs synthetic - and natural is obviously the loser, because soapstone rubs down to nothing in just a few uses!

There cannot be a single debate "just natural vs synthetic in general", because in this context there's no such thing as "natural stones in general" or "synthetic stones in general" - each type of natural stone, and each type of synthetic, is potentially very different, and they can only be considered individually, not in general.

Between the particular granite you've used and the particular synthetic you've used, there's really no contest. But those are not the only natural stone in the world and the only synthetic stone in the world.

jjcobbie3's picture
jjcobbie3

I think there must be some confusion, as the Salzburger mills do not use soapstone for their millstones; rather, they use granite.  These are two different stones.  Soapstone is clearly not a good option for any grain mill.  Granite is clearly a great option since it outperforms synthetics, and is used in commercial industry.

I think you can indeed have a single, general debate regarding natural vs synthetic, since all synthetic stones use a form of adhesive as a binder.  This adhesive will certainly contact your grain, and be found in small quantities in your milled flour.  No such adhesive will ever exist in the flour ground on natural granite stones.  Clearly this is a big difference, and can be applied, and in general, to all synthetic stones.  Likewise, all granite stones clearly are incapable of leaching adhesive into the flour, since they contain no adhesive whatsoever.

Even if there is some synthetic stone out there that has amazing properties, no man-made synthetic-stone object can compete with what our creator has already endowed to his creation.  What he has endowed to us is the perfect grain milling material, namely, granite.

PeterS's picture
PeterS

can have binders which are organic adhesives or mineral based.  The latter are synthetic glasses (stone-like) and chemically/biologically inert.  The binder comprises a small amount of the total mass and the stone would wear so slowly as to never amount to anything significant in the flour.

Commercial mills probably choose their millstones based on cost and not much more: consider the price difference between a granite countertop and a synthetic such as Cambria which are half again more.  The granite may also be more durable in the long run; a factor for an entity milling thousands of pounds of grain per week.  A small custom sized and shaped synthetic millstone is likely more commercially viable for a home or small business mill.

Granite itself is a silica (Quartz; silicon dioxide) blend of a mix of sodium, potassium, calcium alumino silicates which for all practical purposes here is chemically similar to carborundum--a form of aluminum oxide.

Alumino silicates are commonly found in many food products as anti-caking flow agents, and other cosmetic and drug products--with long histories of safe use.

One would have to ingest a few lifetimes worth of bread over a shorter period to notice the effect (hazardous or non-hazardous) on one's existence.  There are many more sources of materials in our lives that present much greater and significant hazards to our well being that a synthetic millstone.

Karen's picture
Karen

I've been lurking here for a long time but felt I had to bite the bullet and join after finding this thread in a Salzburger Getreidemühle search.

I've been lusting after an MT 5 (limed oak--what's not to love?) for a very long time and can finally afford one; unfortunately, that model isn't recommended for grinding Kamut and Einkorn, which is an option that's important. I could either go MAX "SPECIAL" or MT 12 which, to be honest, looks to be too much mill for me. The problem with the MAX is that access to the stones, e.g. to check for glazing, is more difficult than on any of the MT models. Christina, who I believe is the late founder's sister, is a nice lady who's very upfront about each model's strengths and limitations. My first choice years ago was the gorgeous KoMo Classic; I'm kinda glad now it wasn't in the budget because your account of your XL's stones was pretty alarming (I'd have thought they'd be tough in addition to being hard).

I was very impressed by the new Mock Mills, especially given the Pro 100 can handle flint corn (with two passes). However, the Salzburger lure is strong. SG makes the point that not all granite is created equal and that their choice of raw material is meticulous (it bears mentioning that they no longer offer mills with corundum stones, even the cute little Carina now has granite stones). They seem to have a very satisfied niche market. I suspect I'll end up with one model or the other although sinking a grand into an MT 12 isn't very palatable.

Bread1965's picture
Bread1965

I'm looking to buy a mill and am giving serious thought to the Salzburger for the main reason concern you have about the ceramic stone. One consideration I have is how loud it is. I can't seem to find a demonstration video that gives you an honest indication of how loud the machine is. Would you say it's the same as your old Komo +/- ? I don't think I'd buy the MT18. I'm looking at the MT5 but may go up to the MT12. Thanks in advance, frank!

 

jjcobbie3's picture
jjcobbie3

Hi Frank,

 

Sorry for the slow response.  I would say the Salzburger is about the same loudness as the Komo, or slightly louder.  I would call the difference negligible.  Ultimately, the mills without load sound about the same, and the mills under load (while grinding) are much louder as that's when the real work is getting done.  The motor on the Salzburger, itself, is not loud at all, and I would consider it to be very high quality.

Thanks for reaching out, take care!

-Jake

Fernando68's picture
Fernando68

Hi jjcobbie3,

I am considering a Salzburger MT12 and I was wondering if you are still satisfied with your MT18.

I am a little concern about the fact the MT18 shuts off after 4 pounds of flour. The MT18 has a 900W motor, the MT12 has a 550W motor.

How fine is the flour you are grinding? lets say compared to commercial flour

Do you need to "calibrate" the stones touching each other to get to this level of finesse?

Thank you for your help

jjcobbie3's picture
jjcobbie3

Hi Fernando68,

 

I am very happy with the Salzburger MT18 grind quality.  The way I start the mill is with the stones not touching at all, and then I adjust the stones closer together until I get the desired fineness.  What I have learned from trial and error, is that at some point additional fineness does nothing to contribute to better loaf quality.  Some advice I got from the people at Salzburger is to adjust the fineness until you get the desired baking characteristics.  I've found after initially setting the mill to produce super fine flour, that it was actually just stressing the mill without providing any benefit to the bake characteristics or flour yield.

One other thing that I've experienced with my mill, is that the heat dissipation slots are not sufficient to reduce motor heat significantly, and so I did have the mill shut off after approximately 4 lbs of flour.  I have been able to solve this issue by using a air compressor and air nozzle to blow fresh cool air in through one of the slots, and the resulting air that comes out the other slot is quite warm as the cooler air displaces the warmer through the pressure of the air nozzle.  I use a piece of tape to cover one of the slots completely and hold the nozzle in that hole, that way the air is forced to exit the other hole.  By doing this I have been able to successfully grind approximately 15 lbs of flour without the motor turning off.

I hope this helps, and thanks for reaching out,

-Jake

Fernando68's picture
Fernando68

Thank you Jake

Very helpful information

Fernando

 

DANNY's picture
DANNY

Thank you for your post. I really appreciate your input. I'm struggling with all the information out there, but have decided to not go with the mills made from corundum ceramic stones. The challenge I face is the significant difference in cost between Salzburger mill and the Nutrimill Classic Grain Mill. I'm in Canada and the difference in cost is about $800. You obviously can't compare the two but wow what huge  difference. Thanks again. 

Karen's picture
Karen

That's a very substantial difference in price and I don't blame you a bit.

AzJon's picture
AzJon

Just as a point of interest: most toothpaste on the market contains aluminum oxide and you'll likely ingest more of it through daily teeth brushing than through your mill.

 

As a second point of interest: corundum ceramics are used in medical implant devices as well due to their hardness and non-reactive nature.

 

You're honestly in more danger of chemical residue on your grains than you are from the corundum ceramic grind stones.

Kooky's picture
Kooky

Bit of a resurrection here but lots of Salzburger love related to this topic. This alone is worth the price of one, I must order in a few days. Nobody lives forever, but any increase in peace of mind for one's health along the way is worth it.

I switched to "tooth powder" a while ago from a local zero waste store... Organic is not always possible as per the previous comment but definitely preferred.

There is a video of a Salzburger mill completely milling a bowl of pebbles into dust... So the question is, really, since the granite is non-toxic, what the effect of completely powdered stone is on the teeth from high quality German engineering. I presume in the olden days, there would be a large variety of grit sizes. With the engineering of a SB I would guess it's pretty uniform in distribution. I have two mortar and pestles, one of volcanic rock and a cheaper one made of marble... Who knows the effect. Regardless, fresh toasted, pulverized cumin is unbeatable.

Karen's picture
Karen

I wonder which model it is? I ended up buying a small Mockmill because similarly sized Salzburgers can't handle Kamut.

WordDoctor's picture
WordDoctor

zI am so thankful to Nick and Jake for this thread. I am probably going to go with the Salzburger MT18 because of what I have learned here. Thanks again!

Kooky's picture
Kooky

I ended up with the MT12 no plastics based on their chart. It does everything I need with a lower output than the MT18 since I would never need such quantities. 

I love it so much I ended up ordering their gear driven flaker, sieves and wood butter, but I wish I had ordered them all at once to save on shipping. 

WordDoctor's picture
WordDoctor

I am also getting the gear driven flaker and the wood butter. I will probably get the MT12 because that what Christine recommended for us. She said the MT18 was better suited for small bakeries or restaurants!

Kooky's picture
Kooky

Yes, if I ever have the opportunity to open a grain mill around here I will! And I hope they have an industrial, USA ready mill available. If I can afford a Rofco oven I think I will start a small bakery but I don't want to use my personal machine for it.

I love my MT12 so much. I've used it every day since I got it in the mail weeks ago with no sign of letting up. I'll have a 50lb supply of oats on the way soon, both for oat milk and my new daily health breakfast...

Karen's picture
Karen

I'd have liked a plastic-free MT 5 ED until I caught sight of Unfortunately not available in the USA and Canada!.