Beware of Caliche In Your Clay!
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- čas přidán 7. 12. 2021
- I have had a few questions about caliche so here is the video to explain it. What caliche is, what it looks like, when it should be avoided, how to deal with it and when do you want caliche in your clay. The wonderful world of caliche in 15 minutes!
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hello andi, I am a potter from the south of Russia and I have such a rock of soil, for a long time I did not understand what it was and took it for kaolin clay because it turned out to be very similar in properties, also at this place I found quartz crystals and calcite crystals, when adding acetic acid there is a hiss and when firing at 1000 degrees Celsius, it remained water-soluble and did not shrink, but when fired at 1200 degrees Celsius, it shrank by more than 30%, became darker and ceased to be water-soluble, possibly due to shrinkage at high temperature in already hard clay, it leaves a void reducing the pressure on the ceramics from which it ceases to crack.
thank you so much for your work, it is very useful for potters all over the world.
sincerely, shalamovi ceramic.
im glad u made this video because i used to grind caliche and use it as temper
As I mention in this video, I have done that and it worked well for me, so nothing wrong with that as long as you are aware of the potential issue.
@@AncientPottery oh ok. got it
I was thinking the same thing.
I have seen videos where folks use sea shells baked into calcium carbonate and used as temper.
Did you get much breakage?
I grew up in West Texas. We had a lot of caliche. Our county roads were made of it.
Cool we have a lot here in southern Arizona too.
Interesting way to test for caliche; have water and some sort of tube (like a straw or certain grasses), then continuously blow bubbles into the water. By breathing co2 in the water, you're creating carbonic acid which may be able to test for fizzing.
Granted, I just randomly thought of this and it may be hard to get it acidic enough to tell.
Interesting.
Just use vinegar as your acid that you use to test for caliche.
I live just south of Santa Fe , and the land looks very much like where you are. A lot of silt collects in the arroyo behind my dams. To cold now, but I'm chomping at the bit to determine the clay content. A lot of caliche here too. I worked at Acme Brick for 10 years, in Texas. Lime was the bane of their existence. Can you imagine a whole tunnel kiln full of exploded brick? I used to make pottery from the brick clay ( lots of grog) and set it on the end of a kiln car. It came out great... fired at 2000 degrees. I really enjoy your channel.
Wow, thanks for the story. Thanks for watching and commenting.
That would be a bricking nightmare 🤭
Great topic, Andy. I can sure relate. The first couple of wild clay beds I found were full of cliche. I thought I could dig out the visible nodules and levigate the rest, but even after that there wasn't enough vinegar in the world to neutralize it. I started taking an acid bottle with me whenever I went looking for clay, and was finally able to find a calcite-free nice brown clay, which is what I'm practicing on now.
I think that is really the best solution, just keep looking until you find a clean bed.
Are you saying if there is not too much caliche it could be washed out? Or it is just good habit to wash your clay with a vinegar rinse?
@@AncientPottery Hi Andy, so caliche is actually the limestone? This is what you mean?
@@janosszentpeteri1922no. It's a calcium carbonate aggregate with a bunch of nitrates and other stuff. Calcium Carbonate leaches down and glues everything else together.
I love that you call it “wild” clay.🤗🐝❤️
It's actually just a matter of search terms. I previously used the term "native clay" but found that more people were searching online for "wild clay', so I went that way. Check out the hashtag #wildclay there is a lot of great content under that on Instagram.
@@AncientPottery I had already Googled it. I know it’s common to call it wild. I just think it’s cute.🐝🤗❤️
I know understand what happened to the cinderblocks in my basement. They made out basement with bad block and being on the east coast it wasn't long before the cinderblock started kind of exploding, when I would pick the raised piece off the wall there was always a small white chunk underneath that seemed to cause the problem.
Nagyon alapos ember vagy, részletesen és érthetően elmagyarázol mindent, az előadásodat nézve David Attenborough jutott eszembe. :) Klassz kerámiákat készítesz, nagyon tetszik, és mint érdeklődő, próbálkozó köszönöm, hogy bemutatod az ősi technikákat, gratulálok a munkádhoz!
Thank you Andy for raising awareness.
Great show, thank you 😃
Great video, and it's so easy to remember the discount code! LOL! Thanks for the info, Andy, we have found that caliche is in almost every clay deposit out here in Milan New Mexico. We still make some great pottery out of it. We are waiting for some snow and rain to ease the fire danger, then we will post some of our work.
Thanks! I'm not surprised, you live squarely in caliche country as do I. Since you live near Acoma, are you are aware of the problem they had with calcium in their clay back in the 60s? You can literally date an Acoma pot by the calcium spalls on it.
Cool ! I'm in new mexico also, deep into Mimbres pottery. Hope to see some of your work !
I've had some mild chemical burns from clay with limestone in it. Never had any difficulty with spalling, but I did find it necessary to thoroughly soak pots after firing so they weren't corrosive to the touch.
Wow, be careful, I have never heard of that before.
Gloves. They're worth it.
Fartknocker was a genius move. Great knowledge as well!
Ha ha!, thanks
So informative. Thank you
Glad it was helpful!
Giveaway
"Fartknocker" made us bust out laughing. Thank you.
In our area we live on top of a huge limestone self. Its the bedrock in this area and its not very far down. I check our clay with vinegar based upon info in one of your previous videos and it didn't react at all. I think what has happened in our case is. The clay is river floodplain clay that is wet when dug and has been saturated by water for 1000's of years since the melt off of the last ice age. The Area still floods out every spring. My guess is that any lime possibly in the clay has been naturalized over time by the water is was transferred and deposited by. That or as you mentioned its already in such small particles that its acting as a flux in the clay body possibly helping the clay to fire better at the lower temps we achieve. Or its not becoming quick lime because the temps aren't high enough.
Lots of new things to investigate now. Thanks again for another great video
Thanks! At least you are aware of the problem, even if you are not currently effected by it.
Thank you so much, I live in South Eastern OR, we have red clay with caliche on top. I never would have thought it would be a problem. I will be more carful. Thank for the hard work you do.
You are welcome.
Thanks
Great topic Andy. I have experimented with many clays with caliche and I find it unreliable as you mentioned in large amounts, calcium hydroxide, that after fired wet version you mentioned was used by meso America to soften corn for grinding, so ancient southwest people's did understand lime but not sure if they used in pottery though. I even tried calcium hydroxide from fired oyster shells in my mineral paint. No positive results . Onward and upward . Cheers.
Thanks Jeff, and thanks for pointing out that the ancient Natives were aware of lime.
We don't have caliche in Minnesota that I know of but we do have a lot of limestone. I've wondered about using white vinegar instead of water when mixing dry clay. Besides neutralizing some of the calcite I understand it also can improve plasticity. Of course your workroom would smell like pickles. What do you think?
I'm not sure you could apply enough to make much difference but the proof is in the pudding if you could tolerate the small.
I was thinking a hydraulic method of separating, and the thought of vinegar also crossed my mind.
Fun thing roman concrete used quick lime in their brick making material after it had its reaction. So if i wanted to make those having that much would be amazing
Well yeah, it is usable material, just not so much for pottery.
with that much Caliche, i would be tempted on making cement out of it and try to make things out of that
You certainly could.
Calcium carbonate is widespread in the Miami river valley in Ohio where I live since the bedrock layer here is ordovician limestone. I might have to drive east of Columbus outside of the glaciated part of the state to find clay that can be fired safely above 1200°F. I'll definitely try to take a side stop to dig for clay the next time I visit Hocking Hills State Park in south central Ohio.
Or just be really careful in cleaning everything out of your clay.
@@AncientPottery Is caliche the limestone?
Plagued? I got 2 acres to make brick, roads, and I love it in good ol' South town Texas. It's bullet proof
Well to each his own. I think if you were making pottery out of that land or trying to garden in it you might feel differently.
I live in south east asia, the clay here are full with calcium, we can't avoid it, but the native people here just use the clay as it is to make cooking pots. I know in some place in india they mixed their clay for pottery with some wood ash, i think the wood ash somehow neutralize the caliche?
No, wood ash is also full of calcium. If your clay is full of calcium then keep your firing temperatures below about 840 C and you will be fine.
Thank you. I would like to mine my own clay in southern Indiana.
'Nother Texan in the comments, and yes, our clay soil is also rife with limestone. It's a bit of work, but it can be processed of sorts without the acid to make use of its white properties. The reaction with mild acids is the release of co2. It is readily easy to make it into a paste and roll into balls, then fire them at high temp until they're right at the point of falling apart, at which point you get calcium oxide, better known as the colorant of white paint. (I didn't learn this until much later in my career that most any natural paint is the oxide variant of itself). Also a useful hardening agent for DIY mortar added to wood ash and broken fired clays that have been pulverized.
Thanks for the info
Hello, fascinating video and wonderful that you share your knowledge. I've recently moved to Toffia in Central Italy at 263m asl. and here there's a lot of limestone and limestone clay called Galestro in Italian and Marl in English. Medieval potters about 150 miles north of me used this limestone clay for making vessels, and from what I've gleaned they stored the bisque pot submerged in water for several weeks after firing. I wonder if we're using different names for the same thing. I intend to buy some land up here and build a medieval pottery and his Marl appears to be everywhere. I'm wondering what I can use it for, everything has a use. In modern Italy it's used for making cement and industrial tiles and bricks, which makes me wonder if it can be used for building a kiln. Probably not, but free clay is free clay and bricks cost money, and I want my pottery to be all about old skool. I know Marl is used a lot in high temperature glazes and I wonder if it was sieved fine enough would mixing it with porcelain would work for lowering the temperature of porcelain, the two clays have similar properties though Marl is significantly more plastic.
Form your video, I think wet processing is a good way to deal with caliche in the clay.
Yes it can work
I appreciate the advice and I have zero doubt that it's good, but I'm trying to imagine avoiding limestone while trying to find clay in my area. If I dig here, it's essentially 3 inches of sand on limestone. Anything remotely clay-like that I can find is going to be contaminated with limestone here.
Yes, I can understand that, in some areas it can be very hard to avoid. Maybe try a paint strainer bag to filter out all but the finest particles.
I grew up around Dallas Tx. and all my life I've been mistakenly calling our dark grey clay in the soil Caliche Clay. I actually thought that caliche was a type of clay. So now I'm wondering if the dark grey clay in our soil can be used for pottery or not.
Hey Andy, would levigation separate the caliche from the clay or does that not solve the problem?
I was wondering after watching one of your other videos if you lived in the Southwest, beacuse I grew up in California and have lived in Arizona and New Mexico, and the... feel? Style? The way your surroundings look feels so very familiar to me. Comforting really, I still can't get used to all this green in the rest of the US.
Yes, I am in Tucson
when i was a kid and i dug in my backyard i hit a vein of wet white clay, i was told it was caliche but i remember that vein very well, it felt exactly like clay and it did have some chunks of harder white stuff in there... i was just wondering... if i dug it up and did the method you seem to dislike where one pours only the suspended clay in the water out and then added temper to it later... could that work? the problem i am having with identifying clay is that you only show extremely dry clay and the way that it is in the ground is about the exact wetness of clay that would be used to start coiling a pot with. and since i am in south texas. i know the clay in my backyard is most likely riddled with caliche.
Hello, I live in an area that has large amounts of dolomite and bentonite in the clay. The locals tell me the clay is worthless and it would be a waste of time to try and clean it up to make anything useful. How difficult is it to remove those and get a more useful clay?
Hi Andy! Super topic, and one I suppose many of us have had some challenges with at some point. In extreme cases, I've had fired pots disintegrate into crumble over a period of weeks due to limestone in temper. Zia pueblo potters had a problem some years ago with this exact issue, and over time, it adversely affected their market.
I live on the North end of White Sands, can you tell me something about gypsum? I met a guy at a market that said he was using it to make pots...plaster I suppose, but since then I have wondered what happens if it's fired in a clay body containing 3-5%, or used as a slip? Have you had any experience with it? I have it everywhere out here in all it's natural forms!
I live about 80 miles from white sands, I have thought about trying it myself as temper. I'm into the Mimbres pots and we know they did expand that far east of the Mimbres valley
I've had big problems with selenite and gypsum of the same sort as for limestone. Basically, the gypsum (selenite is the crystalline form) turns into plaster of Paris during firing, then heats & swells later. But, as Andy mentioned with calcium carbonate, if it is powdered fine enough, a small amount does not hurt much, though even 0.5mm chunks will cause spalls. Calcium carbonate (limestone & caliche) turn into cement when dehydrated at high temperatures and the same thing happens.
@@coopart1 Hi Jeff, nice to meet you. We should go on a clay hunt someday! Mimbres are fascinating. I know of at least one selenite dagger that was excavated by the U of A some years ago on a Mimbres site, but I've never seen it used in ceramics. Let's try!
@@williamwarner6036 Thanks William, I figured there was a good reason everyone let's this stuff lay on the ground over here. I'm relatively new to this ceramic thing, and all that white "sand" sure does look like mighty fine temper. Seems I got salt in me sugar bowl over here! 😝
@@jeffreyconnell8410 sounds great! We have a lot of various clays here along the mimbres I have found some pretty good smectite with little to no iron . It’s kinda a montmorlinite
How do you ground your clay?
Caliche is better for air drying. that quicklime is the main component to portlan cement.
Is it a bad idea to harvest clay from creek beds? I live in a river valley in southern NY and after harvesting and wet processing clay a few times with different amounts of sand or grog temper added back in, it hasn’t been great for building. The clay seems flimsy even at the start and seems to get harder to work the more temper that’s added.
Not all clay is suitable for building pots. Maybe you should find some better clay to use. It has nothing to do with the creek bed per se, just different clays from different locations have different properties.
Could you potentially fire the material to cause the first reaction, then grind and wet process it to cause the second reaction?
Firing it would ruin the clay and I think the calcium could still turn into calcium oxide in a fire even if it had previously reacted.
I'm fascinated with the idea of incorporating a gem-and-mineral theme into pottery. Instead of glazes this would be more like using an adhesive for affixing polished stones or growing crystals out of, directly onto a piece. Thus there wouldn't necessarily be a need to put a piece into a kiln once it's been fired. So the question is, how can you add something along the lines of calcite (or a mixture to make something like that) onto a fired piece successfully, i.e. to create a milky-white layer on the outside without using plastics, resins or other artificial substances?
No idea, I'm not even sure if it is possible. I have a friend who grew salt crystals on his pottery czcams.com/video/ZPznoGtCxN4/video.html
It's good for mortar though
Would wet processing the clay get rid of the caliche?
It could depending on the form of the caliche. It would be worth a try.
Dose color of clay indicate what heat to fire at or is it plastic quality or just trial and error
Color actually tells us very little about the clay, mostly just trial and error.
@@AncientPottery thank you
D'oh guess what type of clay I just used :( live and learn!
If you keep your firing temperature below about 820 C you should be fine.
Is the grey Michigan "Toledo Clay" usable? It's a huge deposit
no idea, I have never used any clay from Michigan
What's the name of the music at the start of the video?
Sorry this video is over a year old, I have no memory of what song I used.
I live in northern SC Sandhills and see white clay (Kaolin) sometimes... it's widely known in these parts the locals use to eat it for its health properties. Now I'm confused ...is it kaolin or caliche I'm seeing ..kain is clay caliche is sodioum
put vinegar on it, if it is caliche it will fizz, if clay it will not
@@AncientPottery perfect ...that's easy enough thank you!
This probably a dumb question but could dry rice be used to fire small clay things?
Maybe, I fire with wood so it's quite different.
What is a spoll?
Spall: noun, a chip or splinter, as of stone or ore. verb, to break into smaller pieces, as ore; split or chip.
Thanks Andy. I live near a beach and the product of 3 wild collections 4kms away from beach yielded 2cm cube of clay! I went further inland and got some pink and red road cutting dirt @@AncientPottery 🤞
Español por favor
Bro live in Indiana how tf am I gonna avoid limestone 😩
Isn’t adobe made out of caliche?
Not necessarily although it can have some in it
Hot and dry? I won't have to worry about that stuff here then. LOL
Where is that? Oh, I see upstate NY, yes caliche should not be a problem there.
noooo somebody told me I could use calcium, so I just put it in there
Oops!
picks up random rock.... this is limestone!
And it really was. Once you learn how to recognize it, you'll recognize it!
Ha ha! It looked that way, but actually I spent some time hunting down a limestone rock before I started filming.
“Fartknocker”?
When I was in my 20s, me and my friends thought that Beavis and Butthead were the funniest thing we had ever seen. I haven't watched it in years and might find the humor a little immature today, but some of the things they said are still in my vocabulary. "Fartknocker" is one of those things from that show.
Ah, my brother would recognize it then.😆
Our terms are pretty different. I live on the Canadian sheild. Limestone is our way of life, but fruitfully so. I don’t need to to worry about the Cascadian subduction fault. I can’t make pots; You can’t guarantee your future either.
Move away.
I have no idea what so much of this means 😅
At least 300 years over-due. Do yourself a favour.