Clay for finishing off a Rocket Stove mass bench..?

Hi everyone,

We are in the stages of finishing our rocket stove mass which is in the from of a bench. The bulk of the mass is made up of calcium aluminate rapid set cement, granite stones and sand. We want to finish the top with a nice material to sit on, and are looking to use clay. We are in the Scottish Highlands, in an area of granite rock - very little clay, so can not source it from the land here.

Can anyone suggest which clay would be best to use, and where we could source it?

Also what thickness would be suitable as a covering for the mass?

Thank you

Lemuria Love : Welcome to Permies.com, our sister site Richsoil.com, and a big Welcome to the Rocket and Woods stove Forum
Treads, with over 27,000 fellow members world wide you may expect to come here 24 / 7 and find someone how wants to talk about what you
want to talk about ! With widely different backgrounds and widely differing interpretations on life, they will stretch your mind as you will stretch
theirs!

The great Scottish Diaspora has scattered many, many, children of the Tartan all over the globe, and while Lumleys are scarce on the Ground,
we are locally well represented with Loves !

Here in Northern New York State and 'New England' we are 'blessed with some of the oldest rock on the planet, peeking out through our rocky
soil like the rotten teeth in the gums of a Meth-head!

Even here it is possible to find local accumulations of local clay, Good locally found clay may be a secret closely guarded by your local potter,
if you explain you only want enough for your structural cost and a final wash coat(s) this May make them more include to help you!

Also your local Excavation contractor will know every soil type and its depth, and the characteristics of any overburden, within a100 Km circle!

As he will have to pay to have the 'spoil' removed from onsite, and then pay to dump the material, anyone who says they are looking for 'Clean
Fill' -will get his attention. Warning it is your job to test the clay for its suitability before delivery, Once the tailgate drops, and the hoist
raises the bed, its yours forever !

If non of that works, its back to the potter or a college ceramics class to find out where you can get 'Fireclay' put up in 50# bags !

For finish work and testing local clays I can recommend the book " The Hand-sculpted house " Ianto Evans et al ! I hope this helps and is
timely, Big AL

Same sort of situation here...my house sits square on top of the Idaho Batholith...one of the largest single granite formations in the world. My yard is full of the stuff. I recently had to dig a fairly deep trench as part of a drainage system I was putting in, and learned something new...the granite all over the yard appears to be surface deposits from the last ice age...the valley where I live was filled with a glacier that dropped these big stones all over the place about 12000 years ago. When you start digging, it seems like rocks mixed with a little dirt. At about 3-4 feet, you hit a layer of clay. It's very sandy clay, but clay nonetheless... If you dig down far enough, sooner or later you're going to hit the solid bedrock of the batholith itself, but I have no idea how far that is. I'm close enough to the base of the mountain, it's probably not very far.
Anyway, I don't know anything about your local geology, but you never know...if you do some research you might find there's clay closer than you think...

Scott Clark :I have run into the exact opposite situation an old shallow sea bed with a shallow layer of A decent clay of an pale honey, and a further
over burden of clay and silt kinda baby shit yellow, I generally have to dig 6~ish Feet down to get to the good clay !

Way below that is hard packed but plantable dirt! I would not be surprised if you find a layer of Clay/Sand that can be used as Cob / Adobe !

allen lumley wrote:Scott Clark :I have run into the exact opposite situation an old shallow sea bed with a shallow layer of A decent clay of an pale honey, and a further
over burden of clay and silt kinda baby shit yellow, I generally have to dig 6~ish Feet down to get to the good clay !

Way below that is hard packed but plantable dirt! I would not be surprised if you find a layer of Clay/Sand that can be used as Cob / Adobe !

Interesting... The area we're in was somewhere near the east coast of Laramidia, though exactly how close I'm not sure. It's kind of funny, but spending so much time digging for my drain system sparked my interest in local geology. I was really starting to feel like I was one with the ground lol. I had several rocks that were too big to get out in one piece, so I broke them open with a sledge hammer. Kind of fun seeing the bright clean granite inside...got me thinking about how that's the first time in 70 million years that anyone has seen it... The clay layer that I hit seemed to have a lot of sand, but it does hold its shape. We mixed some up with water and put it in a red solo cup, and smooshed the sides up to hollow out the middle. After drying for a few days I popped them out--had a fairly tough clay cup . The kids thought playing with the stuff was great fun... I would think with as much sand as it has in it, I could pretty much use it straight up as cob/adobe after adding some sort of fiber binder.

I'm curious what's under the clay layer, but I'm not sure if/when I'll be able to dig a hole deep enough to find out lol. A quick internet search for Lemuria didn't turn up much, but searches involving "clay" and "Scotland" seem to turn up nothing but clay pigeons...wouldn't have guessed clay targets were as popular as that in the UK.

Scott : The clay layer does not have to be deep, just over a wide area, A couple of decades ago we were faced with the fact that We had lost access
to a sugar bush due to beaver activity and the unwillingness of the Forestry/Conservation people to issue nuisance permits for the beaver !
A genuine hand to god Miracle occurred, a large beaver dam failed and the scouring flood carved a trench in the clay down to a sand, rotten stone layer
and within 4 months the swamp and boggy places were firm enough for 4 wheelers and today we can get logging trucks in there !

We had a very badly stuck Log Skidder punch through the Clay layer and drain some more land, including a favorite fishing pond, much work was put
into trying to 'Fix' the problem, today I would just fence in some pigs there and let them solve the problem! For the Crafts Big AL

Hi everyone and thank you for your replies.

It didn't seem possible for us to source clay from the ground here. We live at the base of a mountain, the soil is rich, but we have found no clay. It is also only accessible by boat which we have to take into consideration with anything we bring over.

After scouring the internet more for ideas and possible solutions, we found a company called Clayworks http://clay-works.com/ and had a really good talk with Adam who runs the company with his wife. He was really helpful and very knowledgeable about building rocket stoves, and cob structures.

We have ordered backing coat clay mix from them, and a clay plaster for the outer layer finish, which is being sent directly to us from Cornwall.

Excited to get it all completed now