Clay Mix

[justinside]

I am trying to figure out the right Clay/Sand mix. I will be using bags of powdered dry clay and builders sand.
I have read so many different websites, threads and watched many youtube videos, some say the mix is 5:1 (Clay/Sand) and others are saying 2:1.
So I am a little confused? Also will regular builders sand work?

I have built several ovens, but they have all been of brick, and want to try Clay.

Thank you

Paul

[cannyfradock]

Hello Justinside......welcome to the forum.

The correct ratio is 2 parts sand to 1 part clay with enough water mixed to make pliable balls that when dropped from waist height, they give just a little...ie don't crumble or flatten out when dropped. A second layer can be added with straw or fine wood-chips added for a thermal layer.

It seems a waste to use powdered dry clay for a cob oven. This stuff is usually bought when making "homebrew" mortar for Pompeii ovens. We try to find an area where clay can be dug out from wasteland (usually found in non-wooded area's about a foot down just below the top soil. Clay for a cob build can also be found for sale (sometimes) at turf suppliers depot's. My local turf supplier sells clay at £12 per ton.

Nothing wrong with powdered clay.....it's just seems an expensive way of building a Cob oven.

All the best with your build.

Terry

[justinside]

Thanks for the info I will look into the turf idea. Stupid thing is I have clay pits all around me in Cornwall, but it seems very white and chalky.
Not sure if that stuff would work? I think it is China clay.

Thanks again.

[cannyfradock]

Paul

Sorry....never heard of china clay. Maybe this thread may be of interest to you with your Clay oven build.... ukwoodfiredovenforum.proboards.com/index.cgi?board=ceovens&action=display&thread=803&page=1 .....have a look at reply #10

Terry

[rivergirl]

Welcome to the forum ! And good luck with your build. I did google , can I make a Cobb oven with white clay and quite a few links came up. So hopefully one of them will help.

[justinside]

I have had no luck finding a turf place that has clay, so I am back to the powdered clay.
If I am to use a 2:1 ratio of sand to clay roughly how many bags of clay should I order?

Thanks

Paul

[cannyfradock]

Paul

The powdered clay that I have used has been powdered fire-clay which is mixed to make a homebrew mix for building fire-brick Pompeii ovens. Excuse my ignorance but I don't even know if there's a difference between powdered fire-clay and powdered clay.

I have used anything up to 1/2 a ton of the wet clay to build a 80cm Cob oven. No idea on the dry clay......perhaps 1/4 ton?......the mix should still be the same 2 parts sand to 1 part clay.

You can ask the advice from Liam from Kilnlinings (just click on his logo on top of the home page to take you to his contact numbers)...he is phone friendly and gives discount to forum members.....he also has a wealth of info.

I hope you get some more response from forum members on this.

Terry

p.s.....I have made a lot of contacts up and down the UK and if you wanted (only if you wanted).....if you give me your local area or town, I could try to source the nearest place to find clay.

p.p.s.....as the forum is quiet at this time of year, please feel free to "bump" this thread from time to time.

[cannyfradock]

Paul

There is an Australian Wood-fired oven website called "Traditional.com" run by a wfo builder called Rado Hand. Here is a link to one of his pages. ....

www.traditionaloven.com/articles/101/what-is-fire-clay-and-where-to-get-it

...it's not really relevant to the UK but has some interesting reading which you may find useful in your build.

Terry

[justinside]

Terry

Thank you, I hope to get more responses also. I will try and call Liam in the morning.

I am thinking it might be easier building an oven like I have before, all with bricks. Just that they are so expensive here in the UK, I only paid about 80p in the States.

Thanks again

Paul

[rivergirl]

Paul have you not got anyone building near you?? It has been said here before that when digging the foundations that if they have hit clay they might let you cart a load off!!

[rodallen]

Hi Terry,

Do you know anywhere near Swansea where I can get some clay to make a cob oven?

Thanks

Rod

[cannyfradock]

Hello Rod......welcome aboard!!.....sorry butI don't know of any particular place in Swansea.

Paul/Rod

I would still try to find a building site...or any small building works where people are digging a trench.....9 times out of 10 they will hit clay near the foot of the trench. Or even some wasteground or allotment etc....it doesn't have to be the sticky stuff. As long as it's not topsoil...it will bind....or like me buy it from turf suppliers or even garden centres will have it.

If you still want to go with bricks Paul, then Liam isn't so expensive....I think his bricks are £1.10p each. The only bug bear is evryone must pay a delivery charge regardless off the amount off £55? (I think there is also a minimum order price?)

Sorry I can't be of any more help.

Terry

[turkey]

Jan 13, 2013 23:02:35 GMT justinside said:

I have had no luck finding a turf place that has clay, so I am back to the powdered clay.
If I am to use a 2:1 ratio of sand to clay roughly how many bags of clay should I order?

Thanks

Paul

if you are buying in powdered clay have you thought about also buying a grog to mix instead of the clay and make a more permanent clay oven?

I think I post more links to this build blog than any other, but its what I was so close to following bar a chance drunken find of firebricks on ebay.

fornoeconomico.blogspot.co.uk/2007_08_01_archive.html

he uses powdered clay with grog and it has the full build process detailed

[rodallen]

Apr 4, 2013 18:42:20 GMT cannyfradock said:

Hello Rod......welcome aboard!!.....sorry butI don't know of any particular place in Swansea.

Paul/Rod

I would still try to find a building site...or any small building works where people are digging a trench.....9 times out of 10 they will hit clay near the foot of the trench. Or even some wasteground or allotment etc....it doesn't have to be the sticky stuff. As long as it's not topsoil...it will bind....or like me buy it from turf suppliers or even garden centres will have it.

If you still want to go with bricks Paul, then Liam isn't so expensive....I think his bricks are £1.10p each. The only bug bear is evryone must pay a delivery charge regardless off the amount off £55? (I think there is also a minimum order price?)

Sorry I can't be of any more help.

Terry

Hi Terry,

Thanks for the tips - I will see what I can find near Swansea and if I cant find anything I would be willing to travel further east. Sorry if its a repeat question - but can you please tell me roughly how much clay and sand you used in total for the last clay oven build?

Cheers

Rod

[debsrizzu]

Hi everyone

We’re based in North London and are looking for somewhere to get clay from....does anyone have recommendations?

Thanks
Deborah