Oven Build Part Three

As I did not have the energy to mix the the second layer of cob, on the same day as the first layer, I left the oven covered over with a wet dust sheet to prevent it from drying out to much before the second layer was applied.
The Second layer of cob was made the same way as the first just was a few hand fulls of straw added. I used garden shears to chop up the straw in to short lengths, roughly 5cm to about 15cm. Once the cob is all mixed, it is applied in the same fashion as the first layer again about 10cm wide, the only difference is the doorway...
As you can see, I left a gap in the second layer for the door to be cut out. It can be quite hard to create the arch over the top of the door, I made sure that it was all pressed firmly together, as it would be a major pain if the doorway collapsed. An important point is the height of the door, there is an ideal height for the opening which is around two thirds of the height of the dome inside, so two thirds of the sand pile in the middle, in the case of this oven it is around 30cm (as my sand pile was about 45cm).
At this part of my build I ran out of clay, so I had to dig up more, it came from a different area, and it produced a different colour and texture cob. but it went on okay and I was able to finish the second layer. (The colour difference can be seen is this picture)Earth ovens can be left link this, though unprotected will not last well in British weather. A "plaster" layer can be applied to make the oven look uniform, or have patterns shaped in to it. The plaster layer is the cob used on the second layer, but with shorter bits of straw, some people use manure and all manner of things, the layer is only about 2.5cm thick, much thinner than the previous layers. I choose to cover my oven in a lime render, I do not know if this was a good idea or not. I thought that lime, unlike cement, can change shape over time, it has some flexibility to it. I left the oven to dry for a few days before coating it in my lime render. I could not find a recipe for lime render, so had a bit of a guess, I think I used about 2 hydrated lime to 3 sand, I also put a very small amount of cement in to the mix to help it harden. Like cob plaster I only put a thin coating on. I left it to dry for a few days under a damp dust sheet, so that it would dry out too quickly.

Then it was time for the final stage, removing the sand. This is quite a rewarding moment. Cutting a hole (I recommend a large knife or similar) just big enough to pull handfuls of sand out (this is so you do not damage the entrance way while removing the sand). Once most of the sand is out the doorway can be made bigger or cut out totally.

And that is it one complete oven, it needs a while to dry out, after a few days a put a small fire inside this one, but it is still very damp, and we are heading in to winter now, so I need to build a shelter to keep the worst of the weather out. Once it is fully dry I shall try to cook something in it... and hopefully a guide to shelter building, not sure how it is going to look yet.
Things to come - Bellows (I hope to start on them soon) and a Shelter for my oven (hopefully before winter)