So here we go! Preparing and adding the first layer of cob.

Now the fun part – making your first layer of cob for the oven.  The recipe for this first layer of cob is generally about 1 part clay to 1 part sand.

A bit about the clay.  Having found our clay dug up from an old dam on a farm – we needed to soak it on a massive tarpaulin for a few weeks. It kind of needs to be malleable.  You can also cheat with some bags of pure clay from the hardware if found clay isn’t available.

You grab a heap of that wet clay and put on a new tarpaulin and add your sand – then stomp and squish with your feet.  It gets messy – so best of have friends to help this.  Then keep bringing the tarpaulin up and over to fold the clay in on itself.   Keep stomping.  Your consistency ends up being such that you can make fairly strong style bricks or balls that if you drop them they don’t break up.  You then slowly build up the first wall with brick type shapes over the newspaper.  Start from the bottom, and just slowly work your way up.    The layer should be at least about 3 inches thick.

After you have finished you need to let it dry a little before cutting the door.   However you don’t want it to be rock hard dry otherwise you won’t be able to cut the door.   We left it for about a few hours – and then cut the door and scooped out the sand.   The dome needs to be strong enough to handle itself when the sand mould is removed – but still soft enough to cut the door.   Make sure during all this time you have a plastic cover or roof ready to throw over in case it rains.    We cut the door out with a sharp knife then very, VERY, carefully scooped the sand out.    The sand needs to be out to assist drying.  You can remove newspaper if you want – but don’t worry. It will eventually burn off.  We then left it for another week to dry at that point.  You can definitely assist this process by burning a wee little fire (your first!) in the door opening with some very small bits of kindling.    Once very dry we added further layers, letting them dry in-between each one.

A little bit about the dimension of the door.  It needs to be wide enough to get a Pizza peel in 🙂 – but not too big to let out too much heat.

Adding the arch

Before we put the next layers on – we need to build the arch and pop in a hole which the chimney will fit in.   That way as we build up the layers we can build up and around.

The brick arch is built in a similar fashion to the dome-  over a sand mould.   But not going to lie to you – this was a bit tricky and it fell down a couple of times! We ended up propping it up with a wooden jig as well until the clay mortar had hardened.  The bricks were angled arch bricks we bought at the same time as the firebricks for the floor.   We also made sure there was a big enough hole size as we built up clay fill in for a chimney.

So lets see what you do for next layers.