Build day! As my parents were so happy to help me dig up some clay I thought I would push my luck and rope them into treading some mud. It is a long day and I was glad of the help. I would never have done it on my own. Thanks Mum, Dad, Claire and baby rosemary for all your help.



So after marking out the shape of the oven on the bricks wit marker pen (so you can still see it when wet) I piled up sand in to a form. using a stick 16" in height stuck in the middle of the form. So when you start to bury the stick you know the exact height. Kiko Denzer in his book says it is really important to get the ratio of height to door height right apparently. 16" seams the ideal height which at a ratio of 63% gives a door height of 10". It is all in the Kiko book. Shape the sand into a perfect dome nicely compacted down. Then layer the finished sand form with damp newspaper. This is so when emptying it you can feel where to stop digging the sand out.



Now comes the clay sand mix. No straw like in a traditional cob mix which gives it strength. In an oven straw just leaves gaps and air which you don't want. You want supper compacted clay and sand for thermal mass. To make the mix you spread out a big tarp and cover it with a couple of buckets of sand and in my case a couple of bucket of clay (broken up in to little wallnut sized bits). Then tread it into to each other with your feet. If you have made pastry it is very much like rubbing the fat into the flour. You need to really thoroughly mix them together. A tarp come in really useful to do this as you can turn it all over really easily by pulling one side of the tarp to the other (the bigger the tarp the better). When you think it is all mixed in really well do it a bit more. add a bit of water till it holds together but doesn't splat when dropped from a waist height and you are ready to start building. You are going to do this a lot of times before the day is out. You want to build the first layer all in one go so you dont get and dry joints which will crack under high heat.



Grab a hand full of mix and compact it down into a solid ball in your hand. build it up this way hand full by hand full (4" thick) until you reach the top. My mix was a bit wet and it started to sag slightly. So the higher we got the thicker the bottom got. So by the time I got to the top the bottom was about 7" thick.



