Wow...you have been busy. I still am confused though.

It seems like the softer (higher talc content) soapstones fade more quickly than the harder varieties like Julia whereas you would think that the higher talcs contents would "hold" oil longer.

So the platyness of the stone may be the main difference between how the stone reacts to water. The higher lamellarity (less compacted), the easier the oil would be lifted from the surface???

I also think one of the reasons that we are seeing more complaints about soapstone's behavior is the fact that so many more people are choosing soapstone than ever. With more stoners, there are going to also be more problems as different quarries get mined out and they move onto less desirables sources.

Thanks for the research.

I admit I am still trying to figure it all out too.

But, the harder stones (like Julia) would have less talc and more of the other minerals and stones in the makeup, so I think that is the main difference. Identifying the other types of stones in the mix is, I think, a big key to the answers. Look at it this way: when you put a sheet of plastic wrap on top of a freshly oiled counter, the area right underneath is going to hold the oil longer, so if there is a "layer" of talc with a "layer" of harder stone on top and then a "layer" of talc, it would (I think) do something similar (you are not going to get this exact type of clean "layer on top of layer" effect in the stone, but the fact that talc seems to form in a sheet like way seems hint that this type of effect might be part of the genetics of soapstone.

The platyness I think explains why some parts of a single counter can go grey much faster than the rest of the counter, and the fact that Soapstone likes oil (and how it "holds" it).

Added to this formula though, is the fact that a counter will oxidize (much like copper). I am not sure if this is because of the talc content or because of the other "stuff" within the stone.

To address the issues of water spotting, here are (what I think are) the variables:

1) The stone variety. The percentage of talc and the presence of other minerals within the soapstone mix.
2) The water and possible minerals that may be attracted to (in particular the magnesium) in the stone.
3) The humidity and/or temperature variation in the environment it is placed
4) The oil/wax that is applied onto the stone

Re: the theory of less desirable sources. I don't think this is the case. The quarries seem to be smaller deposits (than granite quarries) and I think it is a question of when they find one and what kind of stone comes from it. Certainly, the types of rock that is within a soapstone slab mined in India is going to be different from a slab mined in Brazil or one from Vermont. We are seeing the harder varieties now, which are desirable.

Someone reported here that both hard and soft soapstone can be found in the same quarry. It makes sense, then, what you say about how some patches react differently, i.e., it looks uniform, but really isn't.

Thank-you SO much for doing the research!! I have always thought that the "little grooves" explanation for holding oil was missing something. It's so weird that it's hydrophobic (not rabid!) but organophillic, but makes so much sense given how it behaves.

I remember posting it on a thread last year.

I'll quote:
(....)
I received samples from a quarry. I live near it. I asked them if they have to sort out the stone after mining it. In other words if varying hardnesses are all present in one same batch that they dig out in one operation. Which might mean that in a single counter top I might have softer and harder places. They said, "no it is the opposite, we go get the hardness you want in different areas of the quarry which is a huge area almost a square mile. On any given day we only pull out one hardness of stone. We can mine soft stuff which is good for sculptures, or hard stuff which is good for fireplaces and counters." In other words, the hardness is consistent across any given counter top, and secondly that one can specify the hardness one wants to buy. So instead of "Your best bet is to ask about the composition of the stone" just go see it and scratch samples of it. That is what geologists do anyway. They scratch rocks.

--
In the 1970's I went into a talc mine. There was nothing soft about it. There was no visible talc dust. Perhaps I could say there was a slightly oily feel to the stone in some places where the surface was not irregular but the people who were with me said, "yeah, barely."

Nothing got soft and malleable when wet.

Years later i went back in. Same result.

--
Any stone can be reduced to powder form. That's how Silestone Zodiaq Caesarstone etc are made. They are powder glued back together.

Why is talc deemed soft? Well, I guess when it is in powder form it has certain properties.
What makes people think solid talc will let water through it?
Is it because so many Other Stones let water through ?

On the other hand, if a stone has an Oily feel to it, could we not agree that this oiliness might be a clue to its water-repellent properties on a micro level? I'll leave this to a future PhD thesis on capillarity.
---........---
(End Quote)

On another thread (linked to below) I said (quote):
....
I searched high and low in several languages, and found that there is laboratory grade soapstone with a hardness _greater_ than limestone's (about 6), and sculpture grade soapstone, the softest...

According to Wikipedia, soapstone "...undergoes transformations when heated to temperatures of 1000-1200 °C into enstatite and cristobalite; in the Mohs scale, this corresponds to an increase in hardness ..."
If so, does anyone know about Brazing its surface with heat?
I've seen this done to granite.
---........---
(End Quote)

Here is a link that might be useful: Nov 2008 thread: Anybody regret having soapstone?

Thanks for that David.

RE: Talc mines. Even within cosmetic grade talc, finding a "pure" talc is difficult, which explains in part your experience.

Chemical makeup of mineral (not massive talc, the mineral talc) talc (1 on Mohs scale): Mg3Si4O10(OH)2
And that of natural Steatite (about 7.5): 3MgO*4SiO2*4H20

Your note about brazing the surface is interesting. I don't have any idea. Soap doesn't react to the heat of a hot pan, but none of us are playing with anything that is going to come close (at least I'm not) to the 1000-1200 degree mark.

Talc's melting point: reacts at 900 degrees C, melting point at 1500 degress. Maybe Wikipedia was referring to the formation of the metamorphic rock?

But Steatite is an impure stone. So you are going to have other things mixed in.

The harder stones like Julia react very differently to scratching than say the softer Venata. The Mumbai grey I tested I could scratch with a fingernail. Not so with the Minas or the Beleza, for example.

Whhhaaaaaaaat?

Here is a link that might be useful: granite countertops

Sorry granite-girl; I think your reaction is shared by many.

Let me back up a bit:

There seemed to be a lot of discussion about Soapstone oiling and about water spots showing on some stones and not others. No one seems to know why. So...I thought I would do some research to see if we could figure out what the chemistry in the counter is. Figuring this out I thought was key to understanding why some counters seem to show water spots and others not (and also why some counters seem to stay darker for so much longer).

If we could figure out the chemical makeup, it would be easier to find a solution to the waterspot issue in particular.

I know all these counters are called Soapstone, but it is such a general term for so many different stones that vary in color, pattern, and hardness which as it turns out have different base minerals in the makeup of the rock. Talc is certainly the major part of these counters, but I think depending on what else is in the stone, it will "act" differently.

This is not to discount the qualities Soapstone counters share (the resistance to staining, the resistance to damage by setting hot pans on it, etc.), but to try to understand the differences between the types.

If the platyness is linked to the organphillicity of a particular soapstone, this could explain why the relative hardness (which is determined by the amoount of talc) doesn't influence whether or not water produces white rings/spots on the stone. I have to disagree with the "flaky pastry" analogy because this infers that the oil is getting between layers of stone and since soapstone is very dense and considered impervious, I doubt that this is happening. However, I can imagine that larger platlets of organophillic material (ie. talc) could increase the surface area of bonded oil and not allow it to easily leech into a pool of water left sitting on the counter. If this is the case, then the only solution is to wait for the counters to oxidize, (if they do in fact oxidize...I still can't find an explanation for this though the structures given above may provide insight...too bad I was lousy at inorganic chemistry :)) in which case, the oil will still be lifted but the counters will be dark enough to hide the effects.

Ruby, you did a great job digging up this information. Thanks so much for a fun read.

Rubyfig, I really appreciate the time and effort you have taken to look into this problem! Although I am one of the lucky ones who doesn't have a serious issue with rings and spotting, I can see that more and more of us are concerned with this issue. So thank you!

Granite-girl, appreciate your general contributions to stone discussions but would advise against joining in on these topics for the purpose of promoting a business.

Seriously, I think we need to find some chemists to help us all out (I have a fine art background). :)

Re: the flaky pastry analogy. (From my notes, and I cannot remember where I read this) goes back to the minerology of talc: " Talc is a hydrated magnesium silicate. It's elementary sheet is composed of a layer of hydroxyl octahedra, sandwiched between 2 layers of silicon oxygen tetahedra. The main (or basel) surfaces of this elementary sheet do not contain hydroxyl groups or active ions, which explains talc's hydrophobicity and inertness."

Impervious or inert? Because if SS is impervious, where does all that oil go (it doesn't act the same as oil on a sheet of glass)? Maybe the structure of the oil (mineral oil being a petroleum byproduct) breaks down?

The oxidation I think has a lot to do with the magnetite or reactional magnesium carbonates or some of the other minerals that are part of the makeup...still trying to figure that out.

I'm reading all of this and struggling to remember the Organic/Inorganic Chem I took in college that I know are somewhere deep in the recesses of my mind. Now if we can all figure out the cause and then come up with a solution, I say we group together, patent it and market it as the perfect soapstone product.

Got this definition of Oxidization from wisegeek.com

Here is a link that might be useful: What is oxidization?

Mineral oil simple evaporates, people. It is volatile, as a petrochemical.
The white veins so beloved by us fans are the veins of almost pure (and super-soft) talc, I believe.
Pure talc is mohs scale 1, but steatite soapstone like Alberene Church Hill (proud DIY-owner) are approximately mohs 3.2. That's three levels harder than the main component mineral, and must be explained by the presence of harder minerals in significant amounts.
The flaky pastry analogy is flawed. There is nothing to "get in between"; the "flakes" are fused one to another. If it were flaky, water and whatever would permeate through, like baklava soaked with honey. mmmmmmm honey.
Casey

I don't think the veins are pure talc, at least not in the counters I have seen. The veins in my Santa Rita are hard, shiny, glittering veins of quartz. They are harder than the rest of my counter and cannot be scratched like the rest of the counter.

My mom's Black Venata is the same way.

I guess I should have paid attention in my organic chem classes too.

Quartz, eh? Mohs hardness of 7. That places it in the middle between Church Hill Soapstone and Diamond. in terms of hardness.
Casey

Casey, I am struggling with the mineral oil simply evaporating comment. If that were the case, please help me understand why the oil would not dissipate evenly. It seems to correspond the the structure of the stone (in these examples, Beleza):

Day 1, freshly oiled:
{{!gwi}}

Day 1, after a few hours:
{{!gwi}}

Day 2, 1st thing in the morning:
{{!gwi}}

Mineral oil is a volatile compound and definitely evaporates. Remember, when you oil your counters you're removing all but the thinnest layer from the surface of the stone. The uneveness of the evaporation is probable due to several factors: uneveness of the oil film itself, non-uniform adherence of the oil to the stone due to uneven surface texture and varying compostition of the counter surface (ie. the stone itself isn't uniform).

Mineral oil doesn't have the same properties as cooking oil. I'm don't know the composition, but I would guess it's considerably less complex with fewer intermolcular forces holding it together, hence a higher rate of evaporation. I did read that lower viscosity mineral oil evaporate faster than those with higher viscosity. How this relates to Annanna's experience (fewer white rings with thinner mineral oil), I'm not sure.

Did you get instructions with your stone rubyfig? And I forget, how old is your stone???

My counters evaporated oil constantly for several weeks. Bucks County Soapstone told me to oil DAILY for 2 weeks, then every 3 days, then once a week and so on. At around 6 months, the color stabilized. At that point, I had quite the biceps! They supplied me with a thin mineral oil which lasted 6 months. I tried drugstore thick oil after that and hated it. Then I switched to Bee's Oil.

I also found that oiling late at night and wiping off the counters in the am helped keep color longer too. There is not a scientific reason for this as the stone is not absorbing oil but it really did make a difference.

BTW Your stone is really pretty faded too! Was it darker or is that darker than the unoiled state?

Cleo, once again thanks for an informative post. I wasn't given an "oiling schedule" when my stone was installed (I really wish I'd used Bucks County; I liked them so much when I was there but I was worried that black venata would be too soft). I'm definitely going to try yours when I get back in my kitchen.

Thanks Cleo,

I was not given an oiling schedule either (rather, every stone person I spoke to seemed to have a different one). The pictures are literally within the first 24 hours I had the top (It is about a week old now, but I have been locked out of the kitchen since Monday while the floors are being refinished (everything is covered in plastic) and I am dying to know how they are reacting). This coloring within 24 hours is what freaked out the DH.

I have ordered the bees oil (still waiting for it to come, but I will let you know).

But something happens to these stones (chemically I think) when they "season"...and I am trying to figure that out because maybe it will lead to answers with the spotting that some have seen.

What I noticed is that the oil evaporates faster on the side I have the windows , so maybe the heat or the wind is a factor there too.

Your counters seem to be doing what mine did. For the first week especially, the counters faded almost halfway back to unoiled color overnight. And Santa Rita has to be kept dark because of the spots so I was crazed for awhile.

My moms Black Venata from Bucks County Soapstone faded quickly too but she is sticking to their schedule. She is still oiling weekly but it is maintaining the color after 2 months.

I think your counters will be great once you get in there. It is a little scary looking at the thousands of dollars laying on your cabinets and wondering if you did the right thing. I know I felt that in the beginning.

Thanks for all your research.

Another factor that can affect the eveness of the oil is how the counter was finished (sanded). With soapstone less is more. Many "stoners" want to polish soapstone which is exactly the wrong proceedure. Typically I finish soapstone to only about 100 grit.. The more you try to polish it, the more uneven the oil will "take". Areas that are harder will polish more while softer areas will hold the oil, thus looking uneven. Try resanding the stone to 100 grit, I think you will see an improvement. I would suggest trying a left over piece first, or in an area out of the way. Good Luck.

FYI I oil my tops maybe, once every couple of years. The more you use them the less you need to oil and the more even the finish is.

Thanks tom999. Mine has evened out somewhat (it was finished to 150 grit. The oil in my stone seems to have the opposite effect: the harder areas seem to be holding onto it longer), but I was really trying to undestand what is happening when the stone "seasons" (I think it is a reaction to the elements in the stone reacting to both air and oil). Again, I think this might lead to understanding what causes the watermarks some are experiencing.

If I had read these posts before I'd installed soapstone, I would have thought you all had too much time on your hands, but I understand better why this topic merits so much discussion.
I've had my stone for about eight mos. and I'm still learning about it. Thank you all for taking the time to explore this at a deeper level!

How often do my two favourite topics (chemistry and kitchens) come together in one thread? Hmm..where to start?

Although I am a phd level organic chemist, I do not profess to have all the answers for you, but I'm happy to help you understand the info you're digging up. This topic is not a simple one, and indeed when it came up last year, I spoke with my geologist colleague and even he didn't have all the answers.

A couple things though...the waterspotting is NOT due to a chemical reaction between the water and the magnesium compounds in the soapstone. That would have happened the very first time the magnesium came in contact with water, and if it were reversible, it would be at very high temperatures, depending on the specific hydrate formed. In other words, if that reaction were to happen, it have happened way before that soapstone made it's way into your kitchen. More likely the waterspotting is an interaction between the thin coat of oil on the soapstone and the water depending on the amounts of each and the specific makeup of each.

Also, I am not personally convinced that soapstone itself oxidizes as it ages. This is based on my conversation with my geologost friend and my own personal experience with the 45- year old soapstone bench that I spent 5 years working on while completing my doctorate. The geologist pointed out that the soapstone's magnesium silicate is already as oxidized as it gets. Also, even though my bench remained the dark color for long periods, it could be stripped with certain organic solvents to reveal its gray color. These both lead me to believe that it's not the stone itself that oxidizes, but the thin coat of oil that sits on it. I don't have any evidence other than my own personal observations to support this, but thought I'd toss it out there.

Very interesting alku05. In my attempts to stop the water spotting on my own soapstone with various oil/wax products and sandings, I have always been confused as to how the stone itself could oxidize. As you have said, if you strip or resand the stone, it returns to it's original color and then you have to start all over with oiling etc.. if you want it darker. One thing florida joshua from Creative Soapstone has suggested to me is the way the stone is finished could also contribute to water spotting.

Could the water spotting not be attributed to the composition of the water? Since water varies in hardness from place to place combined with the additives most cities put in their water, maybe that would explain why sometimes the same stone variety spots for one person and not another.

We have well water and a Kinetico whole house water softening system. I have wondered about the water as well, although we do not get water spotting on our glasses or dishes.

So, if you bring your soapstone back to it's original grey with acetone or some other way and never put mineral oil or anything else on it, would you still get water spots?? Is there anyone who has never oiled their soapstone at all?

Taking it all in, and trying to dig up a little more info before I open my big mouth. A big thank you to alku05. Your note brings up quite a few questions from me in terms of the organophillicty (I understand that Soapstone has an affinity with "certain" organic compounds, but which ones, I have not been able to find).

Plucky, maybe try "spotting" with a bottle of dasani (did I spell that right). A reverse osmosis cleared water?

Rubyfig: I have had soapstone for about a year (GM original). My experience has been that in the beginning, mineral oil evaporated more quickly. I started using the beeswax that you read about on these boards. (I got it at Sur La Table.) Buffing the beeswax onto the counters definitely made them stay darker longer. Eventually after a few months, we stopped having to oil them as frequently and they still stay dark. Now, we only oil them when we have people coming over. Sometimes I'll just use mineral oil because you don't have to use as much muscle to buff it the way you do with the beeswax.
We still get water spots but I don't really worry about that. We can rub them out with a sponge.
Hope this helps.
DC

Dasani has a fairly high content of sodium in it. Wonder if the salt will affect it differently?

Alku, thanks so much for your wonderful and informative post. I have always been unconvinced that the stone oxidizes and your explanation makes sense. I also agree that the water rings are due to an interaction between the water and oil on the stone. I just wish I knew why it happens on some soapstone varieties and not others. I don't think it's the water because Bayarefrancey tried all kinds of water, including distilled and they all left rings.

Good stuff here. It raises the question of what would speed up the oxidation of the mineral oil. Maybe UV. Since little comes through modern windows, if effective it would explain the long time to turn "naturally" black. Might be worth an experiment with a UV lamp.

kas

Shifting focus for a moment, I was told by a very nice woman at Green Mountain Soapstone, that for soapstone to be countertop grade, it should have between 40% and 70% talc. Does this mean that counters with a higher percentage of talc will be more susceptible to cracking or chipping?

retroreba, the higher the talc content, the "softer" the stone (not necessarly for cracking, but yes for chipping and scratching).

cheril, still trying to figure that out. It seems when I try to get rings (yes, I am trying to get waterspots because I really want to figure this out!), I can only seem to with soap and water (around the soapdish I keep by the sink). I am actually thinking of trying waterlox on a remnant to see how that responds.

It's very likely that they just so happen to sell soapstone that is between 40% and 70% talc; et voila!
Casey