Native Clay

[ceramicfundamentalist]

I've been going through this little studio experiment of using some clay from my area, and I thought I'd share it with you since I'm enjoying it so much. I live on the west coast of Newfoundland which is one of the few areas of the island where there actually are decent deposits of clay. I had long heard that certain potters way back in the depths of time (the 1960s) had used the local clay in making their wares, and when I moved to this coast last summer I decided to go looking for it. Well summer turned into fall, and then to winter, and it's just been this past month since I've gotten around to doing it.

 

My first trip out prospecting I hit pay dirt. I didn't even have good directions - a friend of mine who used this clay 40 years ago told me to just go across the bay and look around. There I found an eroding embankment above the beach, just 6km from my house in the middle of town. I brought a handful back the first trip, then a full bag on the second trip, and finally about 50kg on the third trip. It is actually a nice material straight out of the ground - if you bang it on a table a few times it loosens up and you can handbuild with less than 2 minutes of preparation. There are a few roots and pebbles in it, but the deeper down you dig the less you find of them, and there aren't that many to begin with. For use on the wheel I dried some out completely, then reslaked it, ran it through a sieve and set it out to dry. Without adding a single thing this clay turned into a fine material for throwing. It is a bit less plastic than what I'd expect from a commercial body, and I've had some trouble with cracking, which I think just require me to change the way I work with it. And though I was warned of scumming I've had no problems with that at all. I'm sure I could easily improve the working qualities by adding a few things - sand/grog, silica, fire clay - but part of why I like it so much is because it is perfectly fine just the way nature made it.

 

It's a rich terra cotta colour, and very homogenous and fine grained.

 

The shrinkage is 8.0% while drying, 8.2% at ^06, and 8.7% at ^04.

The absorption is 16.5% at ^06, and 14.8% at ^06.

 

I also plan to fire to ^02, but haven't gotten that far yet. Surprisingly, vessels made from this clay "leak" very little even when covered with a crazed glaze, despite the high absorption. My commercial white earthenware clay has a similar absorption, but leaks like a faucet. I'm not sure what accounts for the difference between the two, but I suspect it is because the commercial clay has silica or other fillers in it which connect the pores to make the clay more leaky.

 

I've attached some pics below of pots made from this clay. I've also been experimenting with using it as a slip and in glazes, though with little success so far. The best thing to come of this material yet is probably the terra sigillata I made with it - a super shiny ruddy surface, that unfortunately, I haven't been able to capture in a photograph.

 

 

[soursop]

Very exciting. I too am very drawn to the idea of digging and using clay fresh from the ground, rather than the prepared pastes we have all become so accustomed to. I live in hawaii however, and the islands here are just too young to have any clay deposits. The closest and most interesting thing I have found and used so far is a native red "clay" that is really just the remnants of an old volcanic eruptions a few million years ago. This stuff has no plasticity what so ever to it, and is really just compressed volcanic ash. Anyway, it did end up making a nice glaze I used use on some of my pieces.

 

I hope you continue to dig your own clay from time to time and maybe seek out new pockets of perhaps different clays to use.

[Chris Campbell]

Wow ... You did get lucky your first time out. It will be interesting to see how high you can fire without losing that fabulous color.

 

Soursop, could you post an image of that glaze made with the volcanic material? Would love to see what it does.

[soursop]

Chris,

 

Here is a photo of the glaze. It is of course the brown splashes inside of each bowl, not the white.

 

I am no glaze formulator. This is what the ash "clay" does as is; sifted and cleaned, then mixed with a bit of water to make a watery paste I could flick on to the bowls. They were fired ^10

[Guest JBaymore]

Nice clay on the mug there!!!!! GREAT find.

 

For glazes at Cone 10 ... try that same clay at 60 - 70 - 80 or 90 percent with wood ash at 40 - 30 - 20 and 10 percent respectively. Adjust as results dictate. Somewhere in there you should get a tenmoku type glaze. As the ash content goes up.... you head toward what the Japanese call an "ame"... or "candy".... an amber gloss glaze that crazes a lot. Add a touch of commercial flint to help decrease the crazing if you want.

 

best,

 

.................john

[Riorose]

I've been going through this little studio experiment of using some clay from my area, and I thought I'd share it with you since I'm enjoying it so much. I live on the west coast of Newfoundland which is one of the few areas of the island where there actually are decent deposits of clay. I had long heard that certain potters way back in the depths of time (the 1960s) had used the local clay in making their wares, and when I moved to this coast last summer I decided to go looking for it. Well summer turned into fall, and then to winter, and it's just been this past month since I've gotten around to doing it.

 

My first trip out prospecting I hit pay dirt. I didn't even have good directions - a friend of mine who used this clay 40 years ago told me to just go across the bay and look around. There I found an eroding embankment above the beach, just 6km from my house in the middle of town. I brought a handful back the first trip, then a full bag on the second trip, and finally about 50kg on the third trip. It is actually a nice material straight out of the ground - if you bang it on a table a few times it loosens up and you can handbuild with less than 2 minutes of preparation. There are a few roots and pebbles in it, but the deeper down you dig the less you find of them, and there aren't that many to begin with. For use on the wheel I dried some out completely, then reslaked it, ran it through a sieve and set it out to dry. Without adding a single thing this clay turned into a fine material for throwing. It is a bit less plastic than what I'd expect from a commercial body, and I've had some trouble with cracking, which I think just require me to change the way I work with it. And though I was warned of scumming I've had no problems with that at all. I'm sure I could easily improve the working qualities by adding a few things - sand/grog, silica, fire clay - but part of why I like it so much is because it is perfectly fine just the way nature made it.

 

It's a rich terra cotta colour, and very homogenous and fine grained.

 

The shrinkage is 8.0% while drying, 8.2% at ^06, and 8.7% at ^04.

The absorption is 16.5% at ^06, and 14.8% at ^06.

 

I also plan to fire to ^02, but haven't gotten that far yet. Surprisingly, vessels made from this clay "leak" very little even when covered with a crazed glaze, despite the high absorption. My commercial white earthenware clay has a similar absorption, but leaks like a faucet. I'm not sure what accounts for the difference between the two, but I suspect it is because the commercial clay has silica or other fillers in it which connect the pores to make the clay more leaky.

 

I've attached some pics below of pots made from this clay. I've also been experimenting with using it as a slip and in glazes, though with little success so far. The best thing to come of this material yet is probably the terra sigillata I made with it - a super shiny ruddy surface, that unfortunately, I haven't been able to capture in a photograph.

 

 

 

[Riorose]

beautiful color. I will be on this road soon, as I am interested to see the portuguese use their own materials instead of buying from Spain. The Spainish come and buy Portuguese raw materials, take it back and then resell it here for 2x the price they sell it for in Spain. In the mean time the Portuguese just seem to accept that their products will come from Spain.