Clay Oven - Mark 2

Well - here goes. Today we made a start on our new clay oven. You may remember that we built one last year with a wooden base... which turned out to be a bad idea, as it burned rather too easily, and we ended up with a heap of charred wood and a pile of cracked clay. 

So today, with a new brick-built plinth, we made a new one. Thanks to Carrington Pottery, we had a big free bucket of dry clay to use in making a new oven, and of course we also had the remains of the old clay oven to recycle. Framework's Gateway to Nature group came to give us a hand, which helped the work to go faster and meant everyone had a chance to get really muddy!

Here's our how to do it guide, a second time with a few modifications.

First, we lined the base of the oven with sand. We actually put in a layer of vermiculite first to help with heat retention in the oven floor, then the sand. After that we put in a brick floor for the oven on top of this, and leveled it, using sand in the gaps to stabilise the bricks. 

Putting in the bed of sand and bricks for the oven base

Meanwhile, the rest of the Framework gang were hard at work crushing the dry clay so we could mix it easily with the sand.

Pulverising the dry clay

Sieving the bashed clay.

Then we needed to tread water into the clay. This is very very messy! On the plus side, it leaves you with lovely smooth feet... You need the resulting mix to be about 50:50 clay and sand, with enough water to hold it together in a firm mix that is still pliable enough to mould into shape. The test is that a ball of the mix, when dropped from shoulder height, will still retain its shape. It's best to mix it on a tarpaulin or on strong plastic (we have lots of off-cuts, after the polytunnel vandalism and recovering last year). As we mixed it, the plastic could be pulled up to easily turn the sides of the mix into the middle, which really helped speed up the process.

Mark from Framework starts mixing water into
the clay using the barefoot technique. It's a bit
like dancing "the twist"...

Regulars Matt and Tracey lend a foot.

Whilst the mortar was being created, we used damp sand to create a dome. This was the mould and showed us how big the internal dimensions of the oven would be. We initially decided how high the oven would be based on how wide we wanted it to be, drawing a circle (with a pen on a string) to mark where it would go. Then using the radius of the circle as the height, we marked this on a stick that we pushed into the centre of the mound to show how high to make it. We also made a template in cardboard to show a quarter arc of the circle and used that in the last stages to create a perfect hemisphere. We had to firm it well so it would keep its shape when we then covered it in clay. We also covered it in aluminium foil so that we didn't end up with an oven that kept shedding sand into the food. We could have used newspaper, but we didn't have any to hand!

The finished sand dome - ready to be wrapped to act as the
internal mould for the oven

The dome covered in foil

We started building up the oven from the base, aiming for about 4-5cm thick walls. We found that putting "guide lumps" of clay of the appropriate thickness against our work tended to help, as it's natural to start to thin the clay as you push and smooth it into place. A lump of clay sticking out shows you how thick it needs to be. 

Once the dome of clay was completed, we slapped it all over to ensure all the clay was firmly bedded in, and then we cut out the door using a sharp knife and removed it. The foil helped here, as you can hear the knife touching it, so you know if you've carved deeply enough into the clay. Apparently height at the top of the curve for this should be 63% of the internal height of the oven. Not sure who decided that, but we hope they are right! The other thing to think of at this stage is making the width of the door big enough to take a baking tray. We made sure there was plenty of room for the one we've got, so that should avoid any embarrassment later on...

The next stage is to wait. The clay needs some time to dry out and harden, so that the oven doesn't collapse or deform when the sand is removed. Hopefully we'll be able to scoop out the sand tomorrow.

Mia helps Dad weed the onion bed.

 Thanks to the Framework folk - you did a great job and saved us hours of work. You've also left us with some beautifully re-painted totem poles, so thank you to the artists as well. And thanks to Mia for helping Dad Mark to weed the onion beds - she's definitely shaping up to be a master gardener when she grows up.

Meet the artists!

Stylish wellies!

Giving our first totem pole a revamp